Dissertations / Theses: 'ZnS nanoparticles'

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Curcio, Ana Laura [UNESP]. "Síntese e caracterização de materiais semicondutores nanoestruturados luminescentes à base de ZnS." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/138154.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Nanocristais tem sido extensivamente investigados nos últimos anos devido à sua ampla gama de aplicações em vários dispositivos tais como sensores, células solares, lasers, fotocatalisadores, fotodetectores, detectores de infravermelhos, diodos emissores de luz, materiais eletroluminescentes e outros materiais emissores de luz. Semicondutores nanocristalinos apresentam propriedades eletrônicas intermediárias entre aqueles de estrutura molecular e sólidos macrocristalinos, proporcionando uma ampla gama de aplicações. Entre estes materiais, o sulfeto de zinco (ZnS) puro ou dopado tem recebido notável atenção por causa de suas propriedades estruturais ópticas, versatilidade e potencial para várias aplicações tecnológicas. O ZnS é um típico semicondutor II-VI, com um gap direto de 3,6 eV à temperatura ambiente e aproximadamente 40 meV de energia de gap, sendo um bom material luminescente utilizado em telas, sensores e lasers. Como material de gap largo, o ZnS pode facilmente hospedar diferentes metais de transição como centros luminescentes. Entre estes íons de metais de transição para estruturas dopadas, os íons Cu2+e Mn2+ são atraentes pelas emissões de luz características e por apresentarem propriedades eficientes para aplicações como luminóforos. A inserção desses íons na estrutura do ZnS proporcionam defeitos que resultam em emissão no verde para os íons Cu2+e emissão no laranja para os íons Mn2+. Neste estudo, as amostras de ZnS pura e dopadas com Cu2+ e Mn2+ foram preparados pelo método solvotermal, que demonstra ser um processo eficaz para preparar nanopartículas. Uma vez preparadas, as estruturas das amostras nanoestruturadas foram caracterizadas e correlacionada s com propriedades fotoluminescentes. Os resultados de difração de raios X mostram que as amostras de ZnS foram cristalizadas completamente sem a presença de fases secundárias e os difratogramas correspondem à estrutura blenda cúbica de zinco com grupo espacial F-43m. Os espectros de XANES (X-ray Absorption Near Edge Structure) teóricos e experimentais na borda K do Zn indicam que a incorporação de átomos de Mn na matriz ZnS causam a formação de vacâncias de Zn e S, a qual é confirmada por ajustes de espectros EXAFS (Extended X-ray Absorption Fine Structure). Estas vacâncias estão relacionadas com um desvio para o vermelho observado no pico do espectro de fotoluminescência devido a adição de Mn na estrutura do ZnS. Para o ZnS puro, o pico é centrado em ~ 504 nm, relativo as vacâncias de S na amostra nanoestruturada. À medida que se aumenta a porcentagem de Mn na matriz ZnS, uma emissão no amarelo-laranja centrada em ~ 590 nm pode ser observada, associada com a transição 4T1-6A1 no interior de níveis 3d de Mn2+. A adição de íons Cu2+ ao ZnS resulta em um alargamento no pico do espectro de fotoluminescência decorrente de emissão no azul-verde, que está relacionada a recombinação de elétrons de níveis de defeitos mais profundos dos estados t2 do Cu próximos da banda de valência.
Nanocrystals has been extensively investigated in recent years due to its wide range of applications in various devices light emitting materials such as sensors, solar cells, lasers, photocatalysts, photodetectors, IR detectors, light emitting diodes and others. Nanocrystalline Semiconductors have electronic properties between those intermediate molecular macrocristalinos and solid structure, providing a wide range of applications. Among these materials, zinc sulfide (ZnS) pure or doped has received considerable attention because of its optical structural properties, versatility and potential for several technological applications. The ZnS is a typical II-VI semiconductor with a direct band gap of 3.6 eV at room temperature and about 40 meV in energy gap, and a good luminescent material for constrution of displays, lasers and sensors. As wide band gap material, ZnS can easily host different transition metals as luminescent centers. Among these ions of transition metal doped structures, Cu2+ and Mn2+ ions are attractive for light emission characteristics and for having effective properties for applications such as phosphors. The addition of these ions in ZnS structure provide defects that result in emission in the green for the Cu2+ ions and emission in orange for the Mn2+ ions. In this study, samples of pure ZnS and doped with Cu2+ and Mn2+ ions were prepared by solvotermal method, which demonstrate to be an effective process for preparing nanoparticles. Once prepared, the structures of the nanostructured samples were characterized and correlated with photoluminescent properties. The results of X-ray diffraction showed that the ZnS samples were completely crystallized without the presence of secondary phases and XRD patterns correspond to the structure of zinc blende to cubic space group F-43m. spectra XANES (X-ray Absorption Near Edge Structure) theoretical and experimental in the Zn K edge indicates that the inclusion of Mn atoms in the ZnS matrix cause the formation of Zn and S vacancies, which is confirmed by spectral adjustments EXAFS (Extended X-ray Absorption Fine Structure). These vacancies are associated with a red shift observed in the photoluminescence spectrum peak due to the addition of Mn in ZnS structure. For pure ZnS, the peak is centered at ~ 504 nm concerning the vacancies in the S nanostructured sample. As it increases the percentage of Mn in the ZnS matrix, in yellow-orange emission centered at ~ 590 nm can be observed, associated with the transition 4 T1- 6A1 inside 3d levels of Mn2+. Adding Cu2+ to the ZnS results in a broadening of the peak of the photoluminescence spectrum due to emission in blue-green, which is related to recombination deeper defect levels of electrons of t2 Cu states near the valence band.

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Raevskaya, Alexandra, Oksana Rosovik, Andriy Kozytskiy, Oleksandr Stroyuk, Volodymyr Dzhagan, and Dietrich R. T. Zahn. "Non-stoichiometric Cu–In–S@ZnS nanoparticles produced in aqueous solutions as light harvesters for liquid-junction photoelectrochemical solar cells." Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-220126.

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A direct “green” aqueous synthesis of mercapto acetate-stabilized copper indium sulfide (CIS) nanoparticles (NPs) and core/shell CIS@ZnS NPs of a varied composition under ambient conditions and a temperature lower than 100 °C is reported. The CIS@ZnS NPs can be anchored to the surface of nanocrystalline FTO/TiO2 films without additional purification or ligand exchange steps yielding visible-light-sensitive heterostructures ready for using as photoanodes in the liquid-junction solar cells. The highest photoelectrochemical activity in a three-electrode cell was demonstrated by a TiO2/CIS@ZnS heterostructure with atomic Cu : In : S and Zn : Cu ratios of 1 : 5 : 10 and 1 : 1. The optimized TiO2/CIS@ZnS photoanodes were tested in two-electrode solar cells with aqueous polysulfide electrolyte and TiO2/Cu2S heterostructures produced by a photo-assisted method as counter-electrodes. Under illumination by a 30 mW cm−2 xenon lamp, the optimized cells showed the average light conversion efficiency of 8.15%, the average open-circuit voltage of −0.6 V and the average fill factor of 0.42. The cells revealed excellent stability and reproducibility of photoelectrochemical parameters with around one percent variation of the light conversion efficiency around an average value for six identical solar cells
Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

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Junior, João Batista Souza. "Síntese de nanoestruturas core/shell de Co/Au magnetoplasmônica e pontos quânticos de CdSe/ZnS." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-28072017-170738/.

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Nanomateriais apresentam propriedades ajustáveis pelo seu tamanho e forma, como o fenômeno de superparamagnetismo em nanopartículas magnéticas ou o confinamento quântico dos portadores de carga em pontos quânticos (quantum dots). Assim, a síntese de nanopartículas esféricas monodispersas torna-se um fator extremamente importante, haja visto que tais propriedades podem ser ajustáveis para diferentes aplicações na área de tecnologia e biomedicina. Nanopartículas magnéticas e quantum dots podem ser apontados como promissores materiais para diagnóstico e terapia de neoplasias (câncer), e o desenvolvimento desses sistemas busca, atualmente, intensificar a magnetização e a eficiência de emissão, respectivamente, relativo às propriedades magnéticas e ópticas, além de outros requisitos. Neste trabalho, nanopartículas esféricas de cobalto metálico foram sintetizadas com diâmetro médio de 5,3 nm e desvio padrão de 0,4 nm, distribuição de tamanhos lognormal. A equação de Langevin modificada pelo modelo de partículas interagentes foi utilizada no ajuste da curva de magnetização M(H) para obtenção do diâmetro magnético médio e desvio padrão, 4,7 nm e 1,0 nm, respectivamente. Comparando os dois diâmetros, encontra-se uma camada morta de magnetização de aproximadamente 3,0 Å a qual, praticamente, não contribui para a magnetização da amostra, sendo a magnetização de saturação de 125 emu g-1. Nanoestruturas core/shell de Co/Au apresentaram a propriedade de ressonância plamon de superfície, uma propriedade adicional também desejada para aplicações biomédicas, sendo este sistema denominado magnetoplasmônico. Quantum dots de CdSe foram sintetizados como elevado controle de tamanho e forma. Utilizando rotas de síntese diferentes dos clássicos procedimentos denominados TOP-TOPO, e dióxido de selênio como precursor, estudos mostraram que na presença de um agente redutor no meio de reação e do solvente 1-octadeceno, as amostras apresentaram melhores propriedades óticas. A estrutura cristalina das amostras de CdSe corresponde à formação da fase blenda de zinco, diferentemente das sínteses TOP-TOPO que levam à formação da fase hexagonal wurtzita. A cinética de crescimento dos quantum dots de CdSe também foram avaliadas através de alíquotas retiras com o tempo de reação mostrando um crescimento exponencial do diâmetro das partículas, como previsto pelas teorias de nucleação e crescimento. Estudos por microscopia de fluorescência mostraram que os quantum dots apresentaram o comportamento de intermitência de fluorescência relatado na literatura como um dos fatores que levam a uma diminuição do rendimento quântico de fluorescência. Nanoestruturas core/shell de CdSe/ZnS foram obtidas com elevado controle da espessura da camada de recobrimento e a intensificação das propriedades de fotoluminescência foram mostradas. Os objetivos do trabalho foram alcançados com sucesso, onde foi possível observar a estabilização e a intensificação da magnetização da fase de cobalto metálico, pouco relatado na literatura. Ainda, foi possível conferir maior estabilidade química, versatilidade de funcionalização da superfície e uma segunda propriedade de ressonância plasmônica com o recobrimento com ouro, sem grande prejuízo da propriedade magnética. Em relação aos sistemas ópticos, os semicondutores de CdSe foram obtidos por nova rota de síntese com expressivo controle de tamanho e forma, recobertos com ZnS intensificando as propriedades ópticas do sistema.
Nanomaterials properties are size- and shape-controlled, such as the superparamagnetism phenomenon of magnetic nanoparticles or the quantum confinement of charge carriers of quantum dots. Therefore, synthesis of monodisperse spherical nanoparticles became extremely important over the past few deacades, since nanoparticles can be used for plenty of applications in technology and biomedicine. Magnetic nanoparticles and quantum dots are promising materials for diagnosis and therapy of cancer. Spherical nanoparticles of metallic cobalt were synthesized with mean diameter of 5,3 nm and standard deviation of 0,4 nm, lognormal distribution. A modified Langevin equation using the interacting superparamagnetic model was used to fit magnetization curves obtaining the mean magnetic diameter and standard deviation, 4,7 nm and 1,0 nm, respectively. The difference between these two diameters was assigned to the magnetic dead layer (∼3.0 Å), which does not contribute to the sample magnetization, being the saturation magnetization of cobalt nanoparticles around 125 emu g-1. Co/Au core/shell nanostructures were synthesized and the surface plasmon ressonance property was observed, an additional property also desired for biomedical applications, being the Co/Au core/shell system called magnetoplasmonic. CdSe quantum dots were synthesized with high size- and shape-controlled. Using different synthetic routes from the classic TOP-TOPO synthesis, and selenium dioxide as a precursor, the results show that and reducing agent is necessary and 1-octadecene solvent leads to better optical properties. CdSe samples showed a zinc blend (cubic phase) crystal structure, different from TOP-TOPO syntheses that leads to wurtzite structure (hexagonal phase). The growth kinetics of CdSe particles were also evaluated through aliquots from reaction showing exponential growth of particles diameter, as predicted on the theory of nucleation and growth. Fluorescence microscopy studies showed that quantum dots exhibited fluorescence intermittence behavior already reported in the literature as one fo the reasons for the quantum yield decrease. CdSe/ZnS core/shell nanostructures were obtained with high control of the coating layer thickness and the increase of the photoluminescence properties were shown.

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Stroh, Albrecht. "Bildgebung von magnetisch markierten Stammzellen in experimentellen Krankheitsmodellen des ZNS mittels zellulärer Magnetresonanztomographie." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2006. http://dx.doi.org/10.18452/15534.

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Die vorliegende Arbeit beschäftigt sich mit der Bildgebung magnetisch markierter Stammzellen im ZNS mittels Magnetresonanztomographie. Dazu wurden Stammzellen mit Eisenoxidnanopartikeln (VSOP, very small superparamagnetic iron-oxide particles) in vitro effizient und ohne zusätzliche Lipofektionsagenzien magnetisch markiert. Es zeigte sich keine wesentliche Beeinflussung der Vitalität, Proliferation und Differenzierungsfähigkeit sämtlicher untersuchter Zellpopulationen. Zur Evaluierung der Grenzen der zellulären MR-Bildgebung wurde das Detektionslimit magnetisch markierter embryonaler Stammzellen in vivo nach intrastriataler Injektion im Gehirn der Ratte untersucht. Es ließen sich bei einer Feldstärke von 17,6 T weniger als 100 magnetisch markierte Zellen sicher vom Hirnparenchym abgrenzen. Die histologische Korrelation bestätigte den zellulären Ursprung der beobachteten T2*-Hypointensitäten. In einem Rattenmodel des Morbus Parkinson konnte eine spezifische Detektion der intrastriatal injizierten magnetisch markierten embryonalen Stammzellen über einen Zeitraum von 6 Monaten erreicht werden. Es konnte keine signifikante Migration der Zellen festgestellt werden, jedoch fanden sich große interindividuelle Unterschiede in ihrer räumlichen Verteilung. In der histologische Analyse stellten sich auch sechs Monate nach der Transplantation im Bereich des Stichkanals eisenoxidmarkierte Stammzellen dar. In einem Mausmodell der cerebralen Ischämie wurde erstmals die Anreicherung systemisch injizierter magnetisch markierter mononukleärer Zellen kernspintomographisch erfasst. 24 - 48 h nach der Injektion magnetisch markierter Zellen stellten sich T2*-gewichtete Signalhypointensitäten im Randbereich der Ischämie dar. Insgesamt zeigte sich in dieser Studie die zelluläre Magnetresonanztomographie zu einem nicht-invasiven Nachweis einer geringen Anzahl magnetisch markierter Zellen über einen langen Zeitraum mit hoher Sensitivität in der Lage.
This thesis is dealing with the imaging of magnetically labeled stem cells in the CNS using magnetic resonance imaging (MRI). Stem cells were efficiently magnetically labeled with very small superparamagnetic iron-oxide particles (VSOP), without any lipofection agents. No significant impact on vitality, proliferation and ability to differentiate could be observed after the magnetic labeling of all cell populations investigated. Magnetically labeled embryonic stem cells were injected into the striatum of rats to evaluate their detection limit by MRI. At field strengths of 17.6 T, less than 100 cells could be discriminated from the brain parenchyma as T2*-weighted hypointensities. Histology proved the cellular origin of MRI-signal changes. In a rat model of Parkinsons’s Disease, magnetically labeled embryonic stem cells could be detected by MRI after intrastriatal injection for a time period of more than 6 months. No significant migration of transplanted cells could be observed, however significant inter-individual differences concerning the spatial distribution of cells could be found. Histologically, transplanted iron-oxide-labeled cells could still be detected in the vicinity of the injection tract six months after transplantation. In a mouse model of cerebral ischemia, the enrichment of systemically injected magnetically labeled mononuclear cells was detected non-invasively by MRI. 24 to 48 hours after injection of magnetically labeled cells, T2*-weighted hypointense signal changes could be observed in the border zone of the ischemia. Over all, this study showed that cellular MRI is capable of the sensitive non-invasive detection of small numbers of magnetically labeled cells over a long period of time.

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Dengo, Nicola. "Ligand-free water-based approaches for the synthesis of metal sulfides nanostructures." Doctoral thesis, Università degli studi di Padova, 2019. http://hdl.handle.net/11577/3424863.

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In this Thesis, metal sulfides were synthesized through water-based and ligand-free synthetic routes. A simple batch approach was successfully employed for the synthesis of ZnS, CuS, PbS, MnS and Ag2S in a crystalline form at a temperature near 0 °C without employing ligands or stabilizing agents. Particles dimension, crystal structure, surface composition and susceptibility to oxidation phenomena of these materials were assessed. In the case of the batch synthesis of ZnS, a SAXS (Small Angle X-Ray Scattering) in-situ study was also performed to elucidate the dimensional evolution of the obtained NPs (nanoparticles) as function of time. Moreover, for ZnS, the behavior in water suspension and the interaction with probe molecules at the liquid/solid interface were also assessed. Microfluidic and CHFS (Continuous Flow Hydrothermal Synthesis) approaches were employed for the synthesis of pure and doped ZnS NPs. In the case of the pure samples, the synthesis conditions were varied in order to gain insights on the growth mechanism of the NPs and to analyze the potential over the control of dimensional and structural properties of the samples. For the doped samples, the uptake of dopants was determined and their inclusion in the ZnS matrix discussed. The functional properties of selected samples were assessed. In particular, the catalytic activity for the HER (Hydrogen Evolution Reaction) was studied for pure ZnS NPs, while PL (Photoluminescence) was measured in the doped ones. Cytotoxicity assays on doped ZnS NPs obtained with the microfluidic route were also performed in view of bioimaging applications. The effect of thermal treatment and oxidation phenomena on ZnS NPs as a function of the NPs size was also in-depth analyzed. The study addressed the variations of size, morphology, structure, composition of the nanostructures and their effect on the photocatalytic activity. The characterization strategy relied on the complementary use of different techniques. XRD (X-Ray Diffraction) and TEM (Transmission Electron Microscopy) analyses were performed to assess mainly dimensional and structural features of the materials, while the surface composition was analyzed combining XPS (X-ray Photoelectron Spectroscopy) and FTIR (Fourier Transform Infrared Spectroscopy). The characterization of the materials was also complemented by Raman spectroscopy. The results showed the potential of the proposed methods to control relevant features of different materials, even without the use of stabilizing agents, and allowed to assess the surface chemistry of the synthesized naked particles.
In questa tesi sono stati sintetizzati solfuri metallici utilizzando metodi in soluzione acquosa che non prevedono l’uso di leganti. In particolare, ZnS, CuS, PbS, MnS e Ag2S sono stati ottenuti in forma cristallina ad una temperatura prossima a 0 °C e senza l’uso di leganti mediante un semplice metodo batch. Sono stati studiati la dimensione, la struttura cristallina, la composizione e i fenomeni di ossidazione delle particelle ottenute. È inoltre stato eseguito uno studio SAXS (Small Angle X-Ray Scattering) in-situ risolto nel tempo relativo alla sintesi di ZnS per valutarne la crescita nella miscela di reazione durante la sintesi batch. Sono inoltre stati studiati il comportamento in sospensione acquosa di particelle di ZnS e la loro interazione con sonde molecolari all’interfaccia liquido/solido. La sintesi di nanoparticelle di ZnS pure e drogate è stata eseguita mediante un metodo microfluidico ed uno CHFS (Continuous Flow Hydrothermal Synthesis). Nel caso di ZnS puro, le condizioni di sintesi sono state variate per ottenere informazioni sul meccanismo di formazione del materiale e valutare le potenzialità dei metodi utilizzati per controllare le proprietà dimensionali e strutturali delle nanoparticelle. Nel caso di ZnS drogato, l’incorporazione dei droganti nel materiale è stata quantificata e discussa. Le proprietà funzionali di alcuni campioni selezionati sono state studiate. Nel caso di ZnS puro è stata quantificata l’attività fotocatalitica per la HER (Hydrogen Evolution Reaction), mentre per il materiale drogato sono state misurate le proprietà di fotoluminescenza. È inoltre stata determinata la citotossicità di alcuni campioni ottenuti per via microfluidica in vista di potenziali applicazioni nella diagnostica per immagini. È stato eseguito uno studio approfondito sull’effetto di trattamenti termici e fenomeni di ossidazione sulle proprietà dimensionali, morfologiche, strutturali e composizionali delle nanostrutture e sui loro effetti sulla di attività fotocatalitica di nanoparticelle di ZnS di diversa dimensione. La strategia di caratterizzazione si è basata sull’uso complementare di tecniche diverse, quali l’XRD (X-Ray Diffraction) e la microscopia TEM (Transmission Electron Microscopy) per lo studio di proprietà dimensionali e strutturali, mentre XPS (X-ray Photoelectron Spectroscopy) e FTIR (Fourier Transform Infrared Spectroscopy) sono state usate per la determinazione della composizione superficiale. La caratterizzazione dei campioni è stata completata dalla spettroscopia Raman. I risultati ottenuti hanno mostrato la potenzialità dei metodi di sintesi proposti nell’ottenere il controllo di importanti proprietà dei materiali senza sfruttare l’uso di leganti superficiali, e hanno consentito lo studio della chimica della superficie esposta delle nanoparticelle sintetizzate.

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Brayek, Amine. "Etude des propriétés photo-électrochimiques des structures cœur-coquille ZnO/ZnS électrodéposées sur verre-ITO." Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC075.

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Les structures à hétérojonction attirent beaucoup d'attention à l'amélioration de l'injection d'électrons à travers l'interface. L'hétérojonction unidimensionnelle ZnS@ZnO est synthétisée sur des substrats conducteurs de verre d'une manière contrôlée, au moyen d'un dépôt électrochimique simple en deux étapes et d'une sulfuration chimique de nanofil de ZnO comme matrice réactive. Les propriétés photoélectrochimiques (PEC) des hétérostructures résultantes ont été mesurées, en utilisant une cellule électrochimique éclairée par une lampe au xénon standard. Les réseaux de nanofils ZnO@ZnS core-shell comme préparé sont trouvés plus efficace pour améliorer significativement la densité de photocourant pour la photoelectrolyse de l'eau comparées aux réseaux de nanofils de ZnO. Ceci est principalement dû à la faible densité de lacunes d'oxygène et d'autres défauts structuraux. La structure électronique particulière dans l'hétérojonction a permis de réduire la hauteur de la barrière énergétique à l'interface et la séparation des porteurs photo-générés est donc améliorée. Ainsi, la performance photoélectrochimique a été fortement améliorée et une densité de photocourant de 0,6 mAcm-2 à 0,6 V (par rapport à Ag/AgC1) a été obtenue. Par conséquent, notre structure proposée est un candidat prometteur comme photoanode pour les dispositifs de conversion de l'énergie en hydrogène
Heterojunction structures are attracting lots of attention for enhancing the electron injection across the interface. ZnO@ZnS one-dimensional heterojunction films are synthesized on conducting glass substrates in a controlled way, using a simple two-step electrochemical deposition and a chemical sulfurization of ZnO nanowire array as reactive template. The photoelectrochemical (PEC) properties of the resulting hétérostructures were measured, using a homemade electrochemical tell illuminated with a standard Xenon lamp. The as-prepared ZnO@ZnS core—shell nanowire arrays are found to exhibit significantly enhanced photocurrent density for water splitting as compared to ZnO nanowire arrays. This is mainly due to the lower density of oxygen vacancies and other defects states. The special electron structure in the heterojunction helped to reduce the energy barrier height at the interface and enhanced the separation of photo-generated carriers. Thus, the photoelectrochemical performance was highly improved, and a photocurrent density of 0. 6 mAcm-2 at 0. 6 V (vs. Ag/AgC1) was obtained. Hence, our proposed structure is a promising candidate as a photoanode for solar energy-to-hydrogen conversion devices

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Zobel, Mirijam [Verfasser], and Reinhard [Akademischer Betreuer] Neder. "Nanoparticle crystallization and solvent interface restructuring especially for ZnO nanoparticles in organic solvents / Mirijam Zobel. Gutachter: Reinhard Neder." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2016. http://d-nb.info/1081544090/34.

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Sandner, Julian Christoph. "Die toxikologische Relevanz der Zn2+-Freisetzung bei der Degradation von ZnO-Nanopartikeln." Doctoral thesis, Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-211704.

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Nanoobjekte werden als eines der meist untersuchten Forschungsgebiete unserer Zeit immer beliebter in der Industrie, da durch Variation ihrer Strukturen besondere Eigenschaften entlockt werden können, die bei makrokristallinen Kompositionen nicht auftreten. Doch mit Zunahme der Anwendungsbereiche steigt wiederum die Wahrscheinlichkeit einer hohen Exposition, was die toxikologischen Untersuchungen der letzten Jahre bedingte. Allerdings wurden dabei weniger die kausalen Zusammenhänge eruiert. In dieser Arbeit zeigt der Autor die Beziehungen zwischen ZnO-Toxizität und intrazellulärer Zn2+-Konzentrationen auf. Zu diesem Zweck erfolgten Zytotoxizitätsuntersuchungen mittels MTT-Test von ZnO-Nanopartikeln und ZnCl2. Dadurch konnten die toxischen Eigenschaften dieser Agenzien belegt werden. Sowohl Nanopartikel als auch Zn2+ weißen in äquivalenter Gesamtmasse dieselben Toxizitätswerte auf. Nachfolgend wurde die Toxizität I) der Partikel durch Chelatierung der Ionen und II) der freigesetzten Zn2+ durch Abzentrifugieren der Partikel untersucht. Hierbei zeigte sich eine deutlich niedrigere Toxizität der Partikel in Abwesenheit von Zn2+. Hingegen verursachten die partikelfreien Proben allein durch die freigesetzten Zn2+ durchaus vergleichbare Effekte wie die ZnO-Dispersion. Erwähnenswert ist, dass generell eine geringere Toxizität durch FKS-Zugabe vorhanden war. Im Weiteren wurde die intrazelluläre Zn2+-Konzentration in Abhängigkeit der Zinkexposition untersucht. Anhand der Markierung mit dem zinkspezifischen Fluorophor FluoZin-3 erfolgte die quantitative Zn2+-Bestimmung mittels Durchflusszytometrie. Dabei ergab sich ein signifikanter Anstieg der intrazellulären Zn2+-Konzentration, der eine einschneidende Störung der Zinkhomöostase darstellt. Bemerkenswert ist der Anstieg in vitalen Zellen auf ein Vielfaches der Ausgangkonzentration, wobei das Überschreiten von etwa 10 nM zum Übergang in die Nekrose führte. Unabhängig von äußeren Faktoren lagen bei gleichen Toxizitätswerten vergleichbare intrazelluläre Zn2+-Konzentrationen vor. Offenbar gibt es einen direkten Zusammenhang zwischen intrazellulären Zn2+ und der Toxizität. Dieser Sachverhalt kann zur Risikobewertung der Nanopartikel herangezogen werden.

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Pujalte, Igor. "Étude in vitro de la toxicité de nanoparticules métalliques (TiO2, ZnO, CdS) sur la cible rénale." Thesis, Bordeaux 2, 2011. http://www.theses.fr/2011BOR21849/document.

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De nombreuses incertitudes persistent sur la toxicité potentielle des nanoparticules (NPs) et leur devenir dans l’organisme humain. L’objectif de ce travail est de mieux comprendre les mécanismes cytotoxiques induits par des NPs métalliques sur une cible secondaire, représentée par le rein. En effet, les NPs sont susceptibles de franchir les barrières cellulaires, d’être véhiculées par le sang pour se retrouver filtrées par le rein au niveau des cellules glomérulaires et peut-être, réabsorbées au niveau des cellules tubulaires. Cette étude est réalisée in vitro, avec des NPs métalliques de titane (TiO2 : 12 nm), de zinc (ZnO : 75 nm) et de cadmium (CdS : 8 nm), sur cellules mésangiales (IP15) et cellules épithéliales tubulaires (HK-2). Les résultats démontrent des effets variables selon le type cellulaire étudié, la nature chimique des NPs et leur solubilité. Si les NPs insolubles de TiO2 (CI50>100 µg/cm²) ne sont que très peu toxiques, les NPs de CdS et de ZnO le sont bien plus du fait de leur solubilité (CI50<7 µg/cm²). La libération de cations métalliques Cd2+ et Zn2+ est à l’origine de cette toxicité. La production d’ERO et la perturbation du statut oxydatif cellulaire (GSH/GSSG) sont corrélées aux effets cytotoxiques des NPs de ZnO et CdS. Une approche moléculaire permet d’identifier les voies de signalisation cellulaire intervenant dans la réponse au stress (translocation nucléaire des facteurs de transcription : Nrf2 et NF-κB). L’internalisation et l’accumulation, des NPs de TiO2 et de CdS, sont responsables de l’induction d’un stress oxydant et d’un effet cytotoxique lors d’exposition sur le long terme
Many uncertainties remain about the potential toxic effect of nanoparticles (NPs), and their becoming in human organism. The aim of this study was to understand the cytotoxic mechanisms induced by metallic NPs, on a secondary target organ, the kidney. NPs were able to cross biological barriers, be carried in blood to kidney cells, on glomerular or tubular cells. This study was performed in vitro, with NPs of titanium (TiO2: 12 nm), zinc (ZnO: 75 nm) and cadmium (CdS: 8 nm), on mesangial IP-15 cells and epithelial HK-2 cells. Results showed effects depending on cell type, chemical nature of NPs and their solubility. TiO2 NPs have no cytotoxic effect (IC50>100µg/cm²), probably due to their insolubility. Exposure to CdS and ZnO NPs lead to cell death (IC50< 7 µg/ cm²). Release of metallic cations Cd2+ and Zn2+ are the main causes of toxicity. ROS production and disruption of oxidative cellular balance (GSH/ GSSG) were correlated to the cytotoxic effects of ZnO and CdS NPs. A molecular approach was used to identify signaling pathways involved in oxidative stress response (nuclear translocation of NF-kappaB and Nrf2).Internalization and accumulation of TiO2 and CdS NPs were responsible of oxidative stress induction and cytotoxic effect on long term exposure

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Norman, Thaddeus Jude. "Optical and structural properties of gold nanoparticle aggregates and Mn 2+, CU 2+, and Ag 1+ doped ZnSe nanoparticles /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2004. http://uclibs.org/PID/11984.

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Zhao, Zhihua. "Systèmes hybrides : de la nanoparticule aux gels." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30118/document.

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Ce travail de thèse porte sur une meilleure compréhension de la croissance de nanoparticules d'oxyde de zinc élaborées à partir d'une approche organométallique. Au cours de ce travail, une analyse de la taille des nanoparticules en utilisant un outil simple basée sur une représentation bidimentionnelle couplée à une analyse statistique multivariée. Elle permet d'extraire la corrélation éventuelle entre la longueur et la largeur des nanoparticules. Cette approche permet de traiter un ensemble de nanoparticules homogène ou hétérogène en taille et en forme. Comparée à l'approche statistique usuelle qui analyse individuellement la distribution de la longueur et celle de la largeur, notre démarche met très facilement en évidence les différents types de nanoparticule et leur anisotropie (ou non). Pour chaque classe de nano-objets considérée, la relation entre la longueur et la largeur, c'est-à-dire les corrélations fortes ou faible entre ces deux paramètres, fourni des informations concernant le(s) mécanisme(s) de nucléation-croissance des nanoparticules. Par exemple, cette approche permet de suivre l'effet sur la taille et la forme de nanoparticules préparées par différents procédés (chimiques ou physique). A partir de différentes images de microscopie électronique extraites de la bibliographie ou de nos travaux de recherche, nous avons démontré l'efficacité et la simplicité de cette approche. De plus, nous avons pu revisiter la synthèse organométallique de nanoparticules de ZnO à la lumière de cette nouvelle méthode de traitement des données. Les nanoparticules anisotropes obtenues par hydrolyse du dicyclohexyl zinc comme précurseur organométallique en présence d'alkyl amine uniquement ont donc été analysées. Le mécanisme de formation a été étudié par analyse systématique des images de microscopie électroniques à transmission et une croissance par attachement orienté a pu être mise en évidence. De plus, nous avons montré que la taille des nanabatonnets d'oxyde de zinc peut être facilement contrôlée en modulant la vitesse d'hydrolyse, le temps de maturation du mélange précurseur organométallique et ligand alkyl amine avant le début de l'hydrolyse, la nature du ligand et la quantité d'eau introduite. Enfin, pendant ce travail, nous avons observé la gélification des milieux réactionnels. L'étude de ce phénomène a permis de développer une approche originale permettant de mettre en forme des matériaux hybride organique-inorganiques. En effet, à partir d'un ensemble d'expériences utilisant la rhéologie, la RMN, la MET, des calculs théoriques, le WAXS ... nous avons pu mettre en évidence une réaction d'oligomérisation entre le précurseur organométallique et les ligands alkyl amine. Cette oligomérisation entre les centres métalliques conduit à la formation de gels, qui peuvent être mise en forme en utilisant des seringues, des tampons ou encore des moules. Des matériaux hybrides d'oxydes métalliques sont ensuite obtenus par hydrolyse du gel. Cette nouvelle approche a été développée pour l'oxyde de zinc puis a été étendue aux oxydes d'étain et de fer. Il s'agit donc d'une approche générale qui ouvre des perspectives intéressantes dans l'utilisation de ces matériaux notamment comme couches sensibles pour des capteurs de gaz
This work is focused on the better understanding of the formation of zinc oxide anisotropic nanoparticle through an organometallic synthesis. To start on this project, the development of a statistical tool to analyze nanoparticle sizes and shapes was mandatory. A simple 2D plot with a multivariate statistical analysis is proposed in order to extract, in particular, the correlation between length and width in a collection or a mixture of anisotropic particles. Compared to the usual statistics on the length associated to a second and independent statistical analysis of the width, this simple plot easily points out the various types of nanoparticles and their (an)isotropy. For each class of nano-objects, the relationship between width and length (i.e. the strong or weak correlations between these two parameters) may suggest information concerning the nucleation-growth processes. It allows one to follow the effect on the shape and size distribution of physical or chemical processes such as simple ripening. Various electronic microscopy pictures from the literature or from our own syntheses are used as examples to demonstrate the efficiency and simplicity of such an analysis. Furthermore, following the organometallic approach, well defined crystalline zinc oxide nanorods are obtained through the hydrolysis reaction of dicyclohexyl zinc precursor without solvent in presence of primary fatty amine only. Their mechanism of formation is studied through a multivariate analysis of TEM results and an oriented attachment process is demonstrated. Taking advantage of this mechanism, the size of the ZnO nanorods can be easily adjusted tuned by controlling adjusting the hydrolysis rate, the aging time before hydrolysis, the nature of ligand, and/or the amount of water. During such experiments, a gelification of the chemical media are for the first time observed. This is the origin of the last part of our work, which put forward an original approach for outstanding processable and reshapable hybrid materials. Indeed, we unequivocally demonstrate through various complementary experiments (rheology, NMR, TEM, theoretical calculation, WAXS...) the formation of oligomeric structures in a mixture of fatty amine with organometallic compounds. This oligomerization reaction between the metallic centers induces the formation of a gel which can be processed into fibers, stamped patterns or molded pieces. Metal oxide hybrid materials are obtained merely by hydrolysis of the organometallic gel, which are furthermore liquid crystal. This unprecedented route towards easily processable hydrid and metal oxide materials is demonstrated for zinc oxide and extended to other metal oxides such as tin oxide and iron oxide, proving the universality of the method and paving the way, for example, to new sensitive gas sensors layers

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Chassaing, Pierre-Marie. "Quelques illustrations du rôle de la surface dans des nanoparticules de ZnO." Phd thesis, Université Paul Sabatier - Toulouse III, 2009. http://tel.archives-ouvertes.fr/tel-00406581.

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Ce travail de thèse porte sur l'étude des excitations élémentaires de la matière dans des nanoparticules de ZnO: phonons et excitons.
Nous montrons que les modes de vibration permettent d'illustrer des effets de surface, lesquels sont de deux types. Premièrement vient la réduction de la taille. L'élasticité linéaire ne décrit plus correctement les modes propres acoustiques pour des tailles inférieures à 2.5 nm. Les expériences que nous avons menées sont en accord avec ce point. Deuxièmement, nous montrons que les ligands qui habillent les nanoparticules sont préférentiellement localisés sur la surface latérale de ces dernières; et qu'ils étirent légèrement la maille cristalline de ZnO.
Concernant les propriétés excitoniques, l'exciton est piégé à la surface des nanoparticules. En outre, de part la dynamique de recombinaison très rapide, le processus de recombinaison de l'exciton est dominé par des mécanismes non-radiatifs.

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Perraud, Igor. "Combustion auto-propagée et mécanosynthèse de ZnS : étude des conversions ZnS <->ZnO et application à la désulfuration des gaz." Thesis, Montpellier 2, 2012. http://www.theses.fr/2012MON20097/document.

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Aujourd'hui, l'impact environnemental de chaque technologie fait l'objet de toutes les attentions. L'élimination des composés soufrés et surtout de H2S dans les gaz entre dans cet aspect écologique au sein de plusieurs processus industriels. L'oxyde de zinc est utilisé comme adsorbant régénérable pour la désulfuration. Le but de ce travail est la préparation de filtres monolithiques macroporeux et de nanopoudres de ZnO avec une forte capacité en soufre et facilement régénérable, ainsi que l'optimisation de leurs propriétés.Des matériaux composites ZnS/NaCl sont tout d'abord synthétisés par combustion auto-propagée à partir de mélanges de zinc, de soufre et de chlorure de sodium. NaCl est éliminé par lixiviation dans l'eau après la synthèse. Les nanopoudres de ZnS sont préparées par mécanosynthèse à partir de mélanges de zinc et de soufre. Les deux matériaux préparés ont des structures cristallines différentes, de type würtzite pour les filtres de ZnS et de type sphalerite pour les poudres. Cette différence est due aux deux voies de synthèse. Monolithes et poudres ZnS sont ensuite convertis en ZnO par traitement thermique sous air à 700 °C.Les transformations macro- et microstructurales des filtres et des poudres ont été étudiées au cours de cycles de sulfuration-oxydation par les méthodes de caractérisation telles que la diffraction des rayons X, la microscopie électronique à balayage et la porosimétrie au mercure. Les résultats montrent que les propriétés des matériaux restent très stables au cours des conversions successives. Enfin, les filtres et nanopoudres de ZnO ont été utilisés comme adsorbants au cours d'essais de désulfuration. La capacité massique en soufre des filtres est assez faible, 6,4 mg S/g ads. montrant que la porosité doit être améliorée. Quant aux nanopoudres, la capacité massique en soufre est très élevée, 272 mg S/g ads, prouvant que la surface spécifique est très importante pour ce type d'application
Today, we have to take care of every technology's environmental effects. The removal of H2S and other sulfur compounds in hot gas enters this ecological aspect in several industrial processes. Zinc oxide is used here as a regenerable sorbent for gas desulfurization. The goal of this work is, the preparation of macroporous ZnO monolithic filters and nanopowders with high sulfur capacity and easily regenerable, and their optimization with the control of their properties. ZnS/NaCl composite materials are first obtained by Self-propagating High temperature Synthesis from mixtures of zinc, sulfur and sodium chloride powders. NaCl is then removed by lixiviation with water. ZnS nanopowders are prepared by mechanical alloying from mixtures of zinc and sulfur. The two materials have different crystalline structure, würtzite type for ZnS filters and sphalerite type for powders, because of the way of synthesis. Then, they are converted into ZnO by thermal treatment under air at 700 °C. Next, the macro- and microstructure transformations of both filter and powders during sulfidation-oxidation cycles are thus considered. Results of all characterizations like X-ray diffraction, scanning electron microscopy and Hg porosimetry show that materials properties are very stable against conversions. Afterwards, ZnO filters and nanopowders are used as adsorbent in desulfurization trials. The sulfur capacity of filters is not so high, 6,4 mg S/g ads and shows that porosity has to be improved. Regarding nanopowders, the sulfur capacity is very high, 272 mg S/g ads, proving that surface area is very important in this application

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Rubio-Garcia, Javier. "Strategies to yield water dispersible ZnO NPs synthesized by an organometallic approach." Toulouse 3, 2010. http://thesesups.ups-tlse.fr/891/.

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Le nombre d'études sur la synthèse et l'application de matériaux semi-conducteurs a augmente au cours des dernières années dû à la dépendance de propriétés physiques et chimiques de ces matériaux avec la taille. Plusieurs applications ont émergées, notamment dans les domaines de la biomédecine, les cellules solaires ou de l'électronique. Parmi les matériaux semi-conducteurs connus, ZnO nanométrique est un bon candidat pour ces applications car il est relativement peu coûteux et respectueux avec l'environnement. Des méthodes physiques et chimiques permettant la production de nanostructures de ZnO ont été décrites dans la littérature. Certaines applications des nanoparticules de ZnO nécessitent des solutions colloïdales et de ce point de vue, les méthodes chimiques sont avantageuses. Dans notre groupe de recherche, une méthode chimique basée sur la décomposition de précurseurs organométalliques en présence d'un agent de stabilisation a été développée. Cependant, cette stratégie ne permet la production de nanoparticules de ZnO uniquement solubles dans les solvants apolaires. Les applications en cosmétiques ou en biomédecine ne sont alors pas possibles. Le but de cette thèse est la modification de la synthèse organométallique pour atteindre des nanoparticules de ZnO solubles dans l'eau: soit par modification des particules synthétisées ou par modifications de la procédure synthèse initiale
There is an ever increasing interest in the synthesis and application of semiconducting materials due to their size-dependent physical and chemical properties (nanometric range). Multiple applications have radically emerged over the last few years including in the areas of biomedicine, solar cells or electronics. Among the semiconducting materials, nanosized ZnO is a good candidate for these applications as it is a relatively inexpensive and environmentally friendly material. Physical and chemical methods allow for the production of ZnO nanostructures. For some applications ZnO nanoparticles (NPs) are required as colloidal solutions and chemical methods are advantageous. In our research group, a chemical method based on the decomposition of organometallic precursors in the presence of a stabilizing agent has been developed. Good control with respect to the average size and the size distribution is achieved. However, this strategy presents as a main drawback the production of ZnO NPs that are only dispersible in non polar solvents. Application for cosmetics or in the field of biomedicine is impeded as a result. The motivation for this Thesis has been to bring about synthetic modification of the organometallic strategy in order to achieve ZnO NPs dispersible in water: either modification of the as-synthesized particles or changes to the synthetic procedure are mandatory

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Balti, Imen. "Nanohybrides inorganique-organiques à base de ZnO, Zn0,95Ni0,05O,coeur-coquille ZnO@γ-Fe2O3 et de polymères bioactifs : Elaboration,propriétés optiques et magnétiques, cytotoxicité." Paris 13, 2012. http://scbd-sto.univ-paris13.fr/intranet/edgalilee_th_2012_balti.pdf.

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Des nanoparticules des oxydes : ZnO, Zn0,95Ni0,05O et coeur-coquille ZnO@γ-Fe2O3 ont été synthétisées par hydrolyse forcée en milieu polyol. Les particules sont quasi-sphériques de diamètre moyen 20-30 nm. Les trois classes présentent des propriétés de photoluminescence alors que les nanoparticules de l’oxyde de zinc dopé au nickel et les nanoparticules ZnO@γ-Fe2O3 sont superparamagnétiques. Grâce à la polymérisation radicalaire contrôlée, deux polymères bioactifs (le poly(sodium-4-styrenesulfonate) et le poly(sodium-4-styrenesulfonate–co–sodium methacrylate)) ont été greffés à la surface de ces nanoparticules. Les nanocomposites ainsi obtenus conservent leurs performances magnétiques et voient leurs caractéristiques optiques s’améliorer. L’enrobage des nanoparticules d’oxyde par les polymères bioactifs réduit la cytotoxicité de ces nanoparticules. Mots-Clés : nanoparticules, propriétés magnétiques et optiques, polymère bioactif,nanohybrides, cytotoxicité
ZnO, Zn0. 95Ni0. 05O and core@shell ZnO@γ-Fe2O3 nanoparticles have been prepared using forced hydrolysis of acetate metallic salts in a polyol medium and coated with poly(sodium-4- styrenesulfonate) and poly(sodium-4-styrenesulfonate–co–sodium methacrylate) via surfaceinitiated atom transfer radical polymerization. The bare nanoparticles display sphericalmorphology with a diameter size laying in the range 20 - 30 nm. The polymer chains weregrown from the surface to yield hybrid nanoparticles with an organic shell of 1 to 3 nm width. The surface modification with polymer did not alter the magnetic and optical properties of bare particles allowing their potential use for biomedical applications. The viability of human endothelial cells was not affected by coated nanoparticles after 48 h of exposition and normal proliferation occurred up to 8 days without alteration of the cell structure. Keywords: nanoparticles, magnetic and optical properties, bioactive Polymer, nonohybrids,cytotoxicity

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Ngo, Van Giang. "Nanoparticules hybrides oxydes métalliques/polymères : synthèse et caractérisation." Phd thesis, Toulon, 2011. http://tel.archives-ouvertes.fr/tel-00768240.

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L'objectif de cette étude consiste à synthétiser et caractériser de nouveaux matériaux hybrides organique/inorganique obtenus par greffage de poly(méthacrylate)s d'alkyle sur des nanoparticules de dioxyde de titane (TiO2) et d'oxyde de zinc (ZnO). Afin de mieux comprendre les facteurs influents les réactions mises en jeu lors d'un greffage à partir de la surface d'un oxyde métallique, nous avons choisi de travailler avec des nanoparticules disponibles commercialement et/ou élaborées. Des nanoparticules d'oxyde de zinc, de dimensions allant de 5 à 100 nm, ont été synthétisées par la méthode de précipitation, à température ambiante. La diffractométrie de rayons X (DRX) et la microscopique électronique à transmission (MET) ont permis de déterminer la structure cristalline, les dimensions et la morphologie des particules ainsi préparées. Les conditions de synthèse ont été optimisées afin d'augmenter la surface spécifique des particules tout en favorisant la présence de groupes hydroxyles en surface. La méthode de greffage de polymères méthacryliques a consisté à modifier préalablement la surface des nanoparticules par un agent de couplage réactif de type 3-méthacryloxypropyltriméthoxysilane (MPS). Les nanoparticules ainsi modifiées ont été caractérisées par spectroscopie (IRTF et RMN CP-MAS 13C et 29Si) et par analyse thermogravimétrique afin de confirmer la présence et la quantité de MPS greffé. Cet alcoxysilane, porteur d'une fonction méthacrylate, a permis de greffer des chaînes de poly(méthacrylate de méthyle), de poly(méthacrylate de tert-butyldiméthylsilyle) à partir de la surface des nanoparticules. La polymérisation radicalaire contrôlée par addition-fragmentation réversible (procédé RAFT) a été sélectionnée pour obtenir un contrôle des masses molaires, de faibles indices de polymolécularité et le greffage de copolymères diblocs. L'observation de ces nanoparticules hydrides en microscopie électronique à transmission montre clairement la présence d'une couronne de polymères à la surface des particules. L'étude de la stabilité thermique des nouvelles nanoparticules hybrides à base de ZnO a été réalisée par analyse thermogravimétrique sous atmosphère inerte. L'impact du procédé de polymérisation sur les mécanismes de dégradation thermique des polymères méthacryliques étudiés a été mis en évidence. Pour la première fois, des valeurs d'énergie d'activation ont été calculées sous atmosphère inerte et oxydante.

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Piolet, Romain. "Synthèse hydrothermale de nanoparticules de ZnO au-delà du point critique : compréhension des étapes de germination et de croissance." Thesis, Dijon, 2014. http://www.theses.fr/2014DIJOS004/document.

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La production hydrothermale de nanomatériaux pulvérulents (de type oxyde métallique) en conditions supercritiques a été largement reportée sans pour autant avoir connaissance des mécanismes de formation de ces nano-objets. Ainsi, cette étude est consacrée à la compréhension des mécanismes de nucléation et de croissance de nanoparticules d’oxyde métallique. L’oxyde de zinc a été choisi comme matériau « modèle ». Dans un premier temps, l’influence des conditions opératoires telles que la pression, la température, le pH, la concentration des précurseurs ou encore les débits des solutions sur les propriétés « nanostructurales » des poudres élaborées (taille, distribution de taille, morphologies) est étudiée. Pour ce faire, deux approches ont été menées en parallèle. La première approche consiste en la mise en œuvre de techniques de caractérisations telles que la diffraction des rayons X ou encore la microscopie électronique en transmission. La seconde concerne le développement d’un modèle de simulation par Mécanique des fluides numérique prenant en compte les phénomènes thermiques et hydrodynamiques mais également la réaction chimique. Les résultats obtenus montrent que les caractéristiques morphologiques déterminées par ces deux approches sont en adéquation. En se basant sur les résultats expérimentaux, plusieurs mécanismes de formation des particules de ZnO sont présentés dans ce manuscrit. Afin d’améliorer le modèle CFD, une méthodologie a été mise en place afin de déterminer les vitesses de nucléation et de croissance des nanoparticules de ZnO au travers de mesures de la solubilité de ce matériau en fonction de la température et de la pression
The supercritical hydrothermal synthesis of nanopowders (especially metal oxide) has been widely studied. To the best of our knowledge, no nanoparticle formation mechanism has been published yet. In this prospect, this study is dedicated to the understanding of metal oxide nanoparticle nucleation and growth mechanisms. For this purpose, zinc oxide is used as a model material. First, the influence of synthesis operating conditions such as pressure, temperature, pH, precursor concentrations and solution flow rates on particle morphological properties (size, particle size distribution or morphologies) has been investigated. Hence, two approaches have simultaneously been carried out. The first approach involves powder characterizations by mean of X-ray diffraction or transmission electron microscopy techniques. The second one consists in the development of a numerical model considering the thermal exchanges, the fluid hydrodynamic behavior and chemical reaction inside the patented reactor by computational fluid dynamics. Results show good agreement between those two approaches. Several ZnO particle formation mechanisms based on powder experimental characterizations are presented in this work depending on operating conditions. In order to enhance the numerical model, a methodology has been set up to evaluate ZnO nanoparticle nucleation and growth rates in supercritical conditions (SCW) by the determination of particle solubility as function of temperature and the pressure

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Jafarov, M. A., and E. F. Nasirov. "Zn1-xCdxS Nanoparticles, Nanofilms, Nanoscale Junction for SolarCells." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34894.

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The In this work the results on the investigation of the precularity near the solar spectrum region, of Zn1-xCdxS nanoparticles, nanofilms, nanoscale p-n and heterojunction prepared on glass-ceramic ad alumminium substrates by precipitation from aqueous solutions are presented. The temperature dependence of dark and light conductivity, spectrum and optical quenching of primary and impurity photoconductivity are investigated. The obtained results show that when controlling ionic composition and heat-treatment (HT) conditions, one can purposely control the properties of Zn1-xCdxS (0 x 0.6) films, achieve the appropriate degree of compensation of different recombination levels and traps attributed to intrinsic defects or impurities, which result in high level of photoelectrical parameters near the IR region. Just after deposition the photoconductivity spectrum maximum of Cd1-xZnxS (0 x 0.6) films is observed at 1 = 0.445 0.495 m versus the film composition. Subsequent to HT, the photoconductivity spectrum considerably widens and appears the impurity maximums at 2=0.58 0.69 m and 3=0.95 1.05 m. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/34894

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Suryajaya. "Study of electrostatically self-assembled thin films of CdS and ZnS nanoparticle semiconductors." Thesis, Sheffield Hallam University, 2007. http://shura.shu.ac.uk/20410/.

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In this work, CdS and ZnS semiconducting colloid nanoparticles coated with organic shell, containing either SO[3-] or NH[2+] groups, were deposited as thin films using the technique of electrostatic self-assembly. The films produced were characterized with UV-vis spectroscopy and spectroscopic ellipsometry - for optical properties; atomic force microscopy (AFM) - for morphology study; mercury probe - for electrical characterisation; and photon counter - for electroluminescence study. UV-vis spectra show a substantial blue shift of the main absorption band of both CdS and ZnS, either in the form of solutions or films, with respect to the bulk materials. The calculation of nanoparticles' radii yields the value of about 1.8 nm for both CdS and ZnS.The fitting of standard ellipsometry data gave the thicknesses (d) of nanoparticle layers of around 5 nm for both CdS and ZnS which corresponds well to the size of particles evaluated from UV-vis spectral data if an additional thickness of the organic shell is taken into account. The values of refractive index (n) and extinction coefficient (k) obtained were about 2.28 and 0.7 at 633 nm wavelength, for both CdS and ZnS.Using total internal reflection (TIRE), the process of alternative deposition of poly-allylamine hydrochloride (PAH) and CdS (or ZnS) layers could be monitored in-situ. The dynamic scan shows that the adsorption kinetic of the first layer of PAH or nanoparticles was slower than that of the next layer. The fitting of TIRE spectra gavethicknesses of about 7 nm and 12 nm for CdS and ZnS, respectively. It supports the suggestion of the formation of three-dimensional aggregates of semiconductor nanoparticles intercalated with polyelectrolyte. AFM images show the formation of large aggregates of nanoparticles, about 40-50 nm, for the films deposited from original colloid solutions, while smaller aggregates, about 12-20 nm, were obtained if the colloid solutions were diluted. Current-voltage (I-V) and capacitance-frequency (C-f) measurements of polyelectrolyte/nanoparticles (CdS or ZnS) films suggest the tunnelling behaviour in the films while capacitance- voltage (C-V) and conductance-voltage (G-V) measurements suggest that these nanoparticles are conductive. The electroluminescence was detected in sandwich structures of (PAH/CdS/PAH)[N] using a photon counting detector, but not in the case of ZnS films.

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20

Rosset, Aurelie. "Synthèse et caractérisation de nanoparticules catalytiques pour une application en photocatalyse solaire." Thesis, Perpignan, 2017. http://www.theses.fr/2017PERP0014/document.

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Cette thèse s’inscrit dans le développement et l’optimisation d’un panel de catalyseurs dopés ou non dopés pour le traitement des eaux usées par un Procédé d’Oxydation Avancée (POA), la photocatalyse hétérogène solaire. Ce procédé de traitement tertiaire pour la dépollution de molécules organiques biorécalcitrantes est limité par l’absorption des catalyseurs dans le domaine de l’UV ne représentant que 5 % du spectre solaire reçu à la surface de la Terre. L’objectif de ce travail est de comparer les efficacités photocatalytiques sous rayonnement UV, visible et solaire dans le but d’améliorer les efficacités dans le domaine de l’UV, de développer un catalyseur exploitant efficacement le rayonnement visible et de définir les paramètres clés régissant les réponses photocatalytiques. Dans cette optique, une étude a été menée sur les catalyseurs de ZnO dopés ou non dopés. L’ensemble des catalyseurs à base de ZnO ont été synthétisé par un seul et même procédé, le sol-gel couplé à un séchage en conditions supercritiques. Les caractérisations structurales, morphologiques, chimiques, optiques et optoélectroniques ont été réalisées en vue de définir leurs paramètres physico-chimiques pour maitriser les conditions de synthèses des catalyseurs. Elles ont également montré que le ZnO dopé décale sa bande d’absorption vers le domaine du visible. Les expérimentations photocatalytiques ont été conduites à l’aide d’un banc de mesure photocatalytique dans le domaine de l’UV, du visible et du solaire. Une attention particulière est portée sur un polluant modèle, le pyriméthanil. En parallèle, ces expérimentations ont été couplées à un modèle cinétique. Les nanoparticules de Zn1-xMxO (M : Ca, Al, Li, V, In, Co, P…) présentent des réponses photocatalytiques prometteuses dans le domaine du visible. Une corrélation a également été mise en évidence entre les propriétés physico-chimiques des catalyseurs et l’efficacité à produire des radicaux. Par ailleurs, une étude plus approfondie a été menée sur le Zn0,90Ca0,10O. Cette étude révèle la présence de défauts structuraux jouant un rôle essentiel sur les réponses photocatalytiques
This thesis is part of the development and optimization of a doped and undoped panel of catalysts for the treatment of waste water based on an Advanced Oxidation Process (AOP), solar heterogeneous photocatalysis. This tertiary process for bio-recalcitrant organic molecules clean up is limited by the catalysts absorption in the UV range which represent only 5 % of the solar spectrum received on the earth surface. The aim is to compare photocatalytic efficiency under UV, visible and solar irradiation in order to improve efficiency in the UV range, to develop a catalyst which operates effectively under visible irradiation and to define key parameters governing the photocatalytic activities. In this context, a study is performed on doped or undoped ZnO based catalysts. All of ZnO based catalysts are synthesized by the same process, the sol-gel process under supercritical drying conditions. Structural, morphological, chemical, optical and optoelectronical characterizations is carried out to define their physico-chemical parameters in order to control the synthesis conditions of these catalysts. Doped ZnO also showed an absorption edge shift toward the visible range. Photocatalytic experiments are carried out with a photocatalysis optical bench in the UV, visible and solar range. Particular attention is paid on a model pollutant, pyrimethanil. In parallel, these experiments are coupled to a kinetic model. Nanoparticles of Zn1-xMxO (M : Ca, Al, Li, V, In, Co, P…) showed encouraging photocatalytic activities in the visible range. A correlation is showed between the physico-chemical properties of the catalysts and the radicals production efficiency. Furthermore, an extensive study is done on Zn0,90Ca0,10O. This study reveals the presence of structural defects playing a main role on the photocatalytic activities

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21

Lee, Kwang Jik. "Study of stability of ZnO nanoparticles and growth mechanisms of colloidal ZnO nanorods." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4303.

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After hydrolyzing zinc acetate in methanol solution, spherical ZnO nanoparticles in the size range from about 2.5 to 5 nm were synthesized by maintaining a ZnO concentration of 0.02M. Compared to ZnO nanoparticles prepared via other methods, the particles prepared using our novel colloidal chemistry exhibit narrow size distribution and a high sensitivity to the surrounding environment. The structure and composition of the white powders precipitated from the colloidal solution can vary, depending on how the powder samples are prepared. Factors such as desorption and adsorption of methanol, binding of water and exposure to humid air have been studied to correlate to the structure and composition observed from the precipitated powder. Methanol desorption rate and excess KOH on the particle surface have played an important role in the structural changes. Furthermore, upon annealing, the white precipitate is recovered to wurtize ZnO. XRD and TEM are used to study the structural transformation of ZnO nanoparticles.

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22

Moussaoui, Myriam. "Elaboration et caractérisations de nouveaux matériaux diélectriques structurés par des nanoparticules de sulfure de zinc : applications prospectives." Thesis, Saint-Etienne, 2011. http://www.theses.fr/2011STET4001.

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Ce travail de thèse a pour objectif la création d’indice optique local et contrôlé dans une matrice vitreuse à travers la mise au point et le développement de procédés de synthèse de nanoparticules (NPs) de sulfure de zinc (ZnS) dans un verre d’oxydes. Nous avons commencé par l’élaboration par voie de fusion d’un verre d’oxydes de composition initiale très simple. Nous avons ensuite examiné la problématique de la synthèse et du contrôle de croissance des NPs de ZnS dans nos échantillons dans trois matrices différentes et par trois traitements : recuit thermique, insolation UV ou par un traitement simultané (recuit thermique + insolation UV). Les propriétés optiques des verres dopés NPs ZnS fabriqués ont été caractérisées par diverses techniques (absorption UV visible, photoluminescence, FTIR, Raman, XPS, mesure d’indice). Il ressort de ces caractérisations que nous arrivons à fabriquer des NPs dans les trois matrices dont la taille peut aller de 1.8 à 7 nm. La dispersion sur les distributions de taille dépend de la matrice, du traitement post-fusion et de sa durée ainsi que de la concentration initiale en dopant. Nous avons également été amené à synthétiser et à étudier des nanopoudres de ZnS. Le procédé de sélection de taille révèle qu’il est possible d’obtenir au moins trois distributions étroites de tailles bien distinctes. Des filtres optiques UV à bande étroite peuvent ainsi être réalisés pour une longueur choisie en contrôlant la taille des NPs ZnS. Des applications prospectives des NPs ZnS pour le nano marquage et la photo dégradation de polluants modèles présents dans l’eau ont été illustrées
Our efforts have been devoted to the development of simple approach to synthesize ZnS nanoparticules (NPs) by melting process in a glassy matrix with the aim to create a controlled optical index variation. In this thesis, we present the formation of ZnS NPs in the glassy matrix and study of their optical properties. The nanocomposite incorporating ZnS in the host medium was prepared using the melting process from a mixture of the raw materials. We have prepared various glass samples with ZnS NPs size ranging from 1.8 à 7 nm. These samples were treated (heat treatment ± UV insulation with 244 nm laser) and characterized by UV-Vis absorption, FTIR, photoluminescence spectroscopy, Raman measurements and XPS. The refractive index measurements of these nanostructured composite glasses have been carried out and show an important increase with ZnS concentrations and treatments. We also present the elaboration of small and monodisperse ZnS nanopowder with size ranging from 3 to 100 nm by a simple, low-cost and mass production chemical method. The NPs were characterised by X-ray powder diffraction (XRD), UV-vis absorption and photoluminescence spectroscopy. The photocatalytic activity of ZnS nanopowders was investigated by using different colorant water dispersed. ZnS NPs appear to be a good candidate for potential environmental applications such as water purification. We also present application of fluorescent ZnS nanoparticles as cellular biomarkers. Fluorescent microscopy images of osteoblastic MC3T3-E1 cells revealed that the ZnS nanoparticles were biocompatible and were penetrated cells and nucleus regardless of their size. Hence, the ZnS NPs can be good candidates for drug delivery and bio-imaging applications

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23

Spisni, Eleonora. "Toxicity assessment of industrial- and sunscreen-derived ZnO nanoparticles." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11272/.

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Lo scopo della presente tesi è l’analisi della tossicità di nanoparticelle di ossido di zinco (nano-ZnO) verso gli organismi acquatici. In particolare, il presente studio valuta per la prima volta l'inibizione della crescita della diatomea Thalassiosira pseudonana indotta sia da nanoparticelle di dervazione industriale, che da nanoparticelle auto-estratte in laboratorio da un filtro solare. Gli esperimenti, condotti presso il Laboratorio di Ingegneria dell'Università di Miami, hanno mostrato che la tossicità indotta dalle nanoparticelle di ossido di zinco è influenzata dal tipo di nanoparticelle, nonché dalla loro concentrazione nella soluzione acquosa e dal tempo di esposizione. In particolare le nanoparticelle di derivazione industriale, più piccole rispetto alle nanoparticelle estratte dal filtro solare, hanno indotto un’inibizione della crescita superiore, specialmente a concentrazioni inferiori. Questo andamento suggerisce che ad alte concentrazioni la tossicità di nano-ZnO potrebbe essere influenzata dall’aggregazione di nanoparticelle (indipendentemente dalle dimensioni di partenza delle nanoparticelle), mentre a concentrazioni inferiori la tossicità potrebbe essere influenzata dalle dimensioni di partenza delle nanoparticelle, così come dal tipo di nanoparticelle e dal tempo di esposizione.

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24

Zhang, Miao. "Defects in ZnO nanoparticles obtained by gas-phase syntheses." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066259.

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L’attribution des signatures spectrales liées aux défauts dans l’oxyde de zinc fait encore l’objet de controverses. Ceci est probablement dû à la grande variété de défauts possibles, à l’incertitude de leur niveau d’énergie ainsi que leur énergie de formation dans la bande interdite. De plus, l’imprécision concernant les conditions de mesures et la possible présence d’impuretés inhérentes à certaines méthodes de synthèse peuvent souvent mener à des interprétations erronées. Le but de ce travail de thèse est donc d’identifier les défauts intrinsèques naturellement présents dans du ZnO fraîchement préparé ou bien formés via différents types de traitements post-synthèse. Pour atteindre ce but, notre stratégie fut (i) de préparer des nanoparticules modèles de ZnO en utilisant deux types de synthèses en phase vapeur (Combustion et CVS) (ii) de combiner des mesures in situ de photoluminescence (PL) et de RPE, également associées à des spectroscopies complémentaires (Raman, UV visible, FTIR) de façon à révéler, attribuer les défauts et discuter leur comportement selon les conditions de synthèses et de traitements post-synthèse et (iii) de révéler la réactivité des surfaces défectueuses de nos échantillons de ZnO en étudiant leur interaction avec des molécules d’eau ou de 2-méthyl-3-butyn-2-ol (MBOH). Nous avons ainsi observé que VO2+ et Zni+ sont les défauts natifs prédominants dans tous les échantillons fraîchement préparés de ZnO, dans des quantités relatives dépendant de la pression partielle d’oxygène utilisée lors de la synthèse. Les lacunes neutres d’oxygène (VO0) ont également été détectées dans le cas des préparations effectuées dans des conditions particulièrement riches en zinc. VO+ peut se former dans le ZnO smoke après post-traitement (recuit sous vide ou sous vapeur de zinc), la formation d’électrons associée participant à la réduction de Zni+ en Zn0. Au contraire, calciner sous O2 mène à des processus opposés, voire, sous excès d’O2, à la formation de défaut de type Oi. La dissociation de l’eau sur des surfaces préalablement calcinées sous vide mène au remplissage de VO+ et à la réduction de Zn2+ en Zn+. Des tests catalytiques de conversion du MBOH ont montré que de tels processus redox, contrôlés par les conditions de prétraitement, affectent la réactivité de surface de nos matériaux
By far, the assignment of defects-related spectroscopic features of zinc oxide is still a matter of great controversy. This is probably due to the variety of possible defects in ZnO as well as to their still uncertain formation energies and positions within the band gap. Uncontrolled measurement conditions and impurities related to some synthesis methods can additionally mislead interpretations. The aim of this work is to identify the intrinsic native defects in pure ZnO or formed upon different kind of post-synthesis treatments. To fulfill this goal our strategy was to: i) prepare model zinc oxide nanoparticles using two different vapor-phase synthesis techniques (Combustion and CVS) ii) identify, assign and discuss the occurrence of the defects in line with the synthesis and post treatments conditions by combining in situ PL and EPR measurements together with other complementary spectroscopies (Raman, UV vis, FTIR) and iii) reveal the surface reactivity of defective ZnO samples by studying the interaction with water or 2-methyl-3-butyn-2-ol (MBOH). We observed that in all as-synthesized ZnO samples VO2+ and Zni+ are the predominant native defects with relative amounts depending on the partial pressure of oxygen used during the synthesis. Neutral oxygen vacancies (VO0) are additionally detected in samples prepared in conditions particularly rich in zinc. The formation of Vo+ is demonstrated in ZnO smoke upon post treatment (annealing in high vacuum or zinc vapor) while the associated electron release is shown to participate to the reduction of Zni+ into Zn0. On the contrary, annealing in oxygen leads to reverse processes while if used in an excess, to creation of Oi-related defects. Dissociation of water on vacuum annealed surface leads to the filling up of VO+, and reduction of Zn2+ into Zn+. Such redox processes controlled by the pretreatment conditions affect the surface reactivity through the change of the acid base balance, as revealed by MBOH conversion catalytic tests

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25

Van, Zandt Nicholas L. "Aqueous Fabrication of Pristine and Oxide Coated ZnSe Nanoparticles." Wright State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=wright1623356039586297.

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26

Hagelin, Alexander. "ZnO nanoparticles : synthesis of Ga-doped ZnO, oxygen gas sensing and quantum chemical investigation." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-64730.

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Doped ZnO nanoparticles were synthesized by three different methods – electrochemical deposition under oxidizing conditions (EDOC) , combustion method and wet chemical synthesis – for investigating the oxygen gas sensing response. Ga-doped ZnO was mostly synthesized but also In-doped ZnO was made. The samples were analyzed by XRD, SEM, EDX and TEM. Gas response curves are given alongside with Langmuir fitted curves and data for pure ZnO and Ga-doped ZnO. DFT quantum chemical investigation of cluster models ZnO nanoparticles were performed to evaluate defect effects and oxygen and nitrogen dioxide reactions with the ZnO surface. Defects were investigated by DOS and HOMO-LUMO plots , and are oxygen vacancy, zinc vacancy, zinc interstitial and gallium doping by replacing zinc with gallium. Oxygen and nitrogen dioxide reactions were investigated by computing Mulliken charges, bond lengths, DOS spectra and HOMO-LUMO plots.

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27

Taïnoff, Dimitri. "Influence des défauts sur les propriétés optiques et électroniques des nanoparticules de ZnO." Phd thesis, Université Claude Bernard - Lyon I, 2009. http://tel.archives-ouvertes.fr/tel-00507281.

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L'objectif de cette étude est de mieux comprendre le rôle joué par les défauts dans les propriétés optiques et électroniques des nanostructures d'oxyde de zinc. Pour ce faire, nous avons synthétisé des nanoparticules d'oxyde de zinc de 6 à 18 nm de diamètres pouvant être considérées comme modèle en terme de stœchiométrie, de cristallinité et de qualité de surface par une méthode physique originale : la Low Energy Cluster Beam Deposition.La caractérisation optique des défauts présents dans les nanoparticules de ZnO a été faite grâce à l'analyse des spectres d'émission visible et UV à différentes températures [10K-300K]. En particulier la luminescence excitonique à 3,31 eV, qui est un sujet controversé, a été étudiée en comparant la luminescence excitonique d'échantillons structurés à différentes échelles (nanoparticules, microcristaux et monocristal). Les temps de déclins très rapides des défauts donneurs ont été étudiés par spectroscopie à décalage de fréquence au CELIA à Bordeaux révélant une dépendance en fonction de la taille des NPs du type Giant Oscillator Strenght.Les propriétés de transport électronique des couches minces de NPs, naturellement dopées n, ont été caractérisées grâce à des expériences σ(T). Différents scénarios sont proposés pour expliquer les résultats des expériences de conductivité, et discutés en fonction des propriétés optiques des couches et de leur morphologie. En particulier, il est montré que la surface des NPs, très réactive, influence fortement le transport, ce qui laisse entrevoir la possibilité d'utiliser ces films nanostructurés comme capteurs de gaz.

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Fernando, Joseph F. S. "Crystal seeding and photochemistry of gold-zinc oxide hybrid nanoparticles." Thesis, Queensland University of Technology, 2016. https://eprints.qut.edu.au/101206/1/Joseph_Fernando_Thesis.pdf.

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This project investigated the synthesis of hybrid nanoparticles of gold and zinc oxide by using photodeposition and crystal seeding approach. The study extended our understanding of the factors that determine nanocrystal size, shape and ratio of gold and zinc oxide in the hybrid system. Control at this scale is important from a materials-engineering viewpoint and for technological applications such as nonlinear optics, photocatalysis and photovoltaics. This research found that nonlinear optical absorption of zinc oxide can be enhanced by several orders of magnitude by coupling zinc oxide nanoparticles to gold nanoparticles.

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Cruz, González Sara. "Availability of metal ions and ZnO nanoparticles in aqueous media." Doctoral thesis, Universitat de Lleida, 2015. http://hdl.handle.net/10803/314762.

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La presència de determinats metalls, ja sigui en forma del metall lliure, formant complexos amb lligands o en forma de nanopartícules metàl•liques té efectes negatius en el medi ambient. Per aquest motiu, l’estudi de la disponibilitat de metalls és important per determinar el seu impacte mediambiental. En aquest treball s'ha estudiat un sistema i una tècnica per a la mesura de la disponibilitat. El sistema té la particularitat de contenir, en dispersió, nanopartícules d’òxids metàl•lics. Una primera part de l’estudi s’enfoca a la caracterització físic-química de dispersions sintètiques de nanopartícules. Aquesta part estudia l’efecte que tenen les condicions del medi (pH, salinitat, contingut de matèria orgànica, etc.) en el comportament de les nanopartícules. S'han determinat processos com són l’agregació, solubilització i sedimentació, en funció de les condicions del medi. Tots aquests processos juguen un paper molt important en el destí de les nanopartícules en el medi ambient i en la seva toxicitat. La segona part d’aquesta tesi es centra en l’aplicació de la tècnica analítica DGT (Diffusive Gradient in Thin films) per la mesura de fluxos de metall disponibles en solucions aquoses. En el present treball, s’ha determinat la solubilitat de nanopartícules en dispersions aquoses. Per altra banda s'ha estudiat la tècnica DGT des d’un punt de vista físic-químic. Les contribucions dels fluxos de complexos s’avaluen amb un paràmetre que té en compte les constants de dissociació dels complexos així com la seva difusió. S'han estudiat les acumulacions de metalls que en solució tenen com especies dominants complexos carregats elèctricament. Si aquesta càrrega és negativa, l’acumulació disminueix en baixar la força iònica i a l’inrevés en el cas contrari. Aquest fenomen s’explica per la repulsió electrostàtica entre la càrrega negativa del disc de resina i el complex quan aquest és parcialment làbil. En conclusió, la resina sembla jugar un paper més actiu del que es pensava en l’acumulació de metalls en DGT.
La presencia de determinados metales, ya sea en forma del metal libre, formando complejos con ligandos o en forma de nanopartículas metálicas tiene efectos negativos en el medio ambiente. Por este motivo, el estudio de la disponibilidad de metales es importante para determinar su impacto medioambiental. En este trabajo se ha estudiado un sistema y una técnica para la medida de la disponibilidad. El sistema tiene la particularidad de contener, en dispersión, nanopartículas de óxidos metálicos. Una primera parte del estudio se enfoca a la caracterización físico-química de dispersiones sintéticas de nanopartículas. Esta parte estudia el efecto que tienen las condiciones del medio (pH, salinidad, contenido de materia orgánica, etc) en el comportamiento de las nanopartículas. Se han determinado procesos como son la agregación, solubilidad y sedimentación, en función de las condiciones del medio. Todos estos procesos juegan un papel muy importante en el destino de las nanopartículas en el medio ambiente y en su toxicidad. La segunda parte de esta tesis se centra en la aplicación de la técnica analítica DGT (Diffusive Gradiente in Thin films) para la medida de flujos de metal disponibles en soluciones acuosas. En el presente trabajo, se ha determinado la solubilidad de nanopartículas en dispersiones acuosas. Por otra parte se ha estudiado la técnica DGT desde un punto de vista físico-químico. Las contribuciones de los flujos de complejos se evalúan con un parámetro que tiene en cuenta las constantes de disociación de los complejos así como su difusión. Se han estudiado las acumulaciones de metales que en solución tienen como especies dominantes complejos cargados eléctricamente. Si esta carga es negativa, la acumulación disminuye al bajar la fuerza iónica y viceversa en el caso contrario. Este fenómeno se explica por la repulsión electrostática entre la carga negativa del disco de resina y el complejo cuando éste es parcialmente lábil. En conclusión, la resina parece jugar un papel más activo de lo que se pensaba en la acumulación de metales en DGT.
The presence of certain metals, either in the form of free metal, forming complexes with ligands or as metal nanoparticles has negative effects on the environment. For this reason, the study of the availability of metals is important in determining its environmental impact. In this work a system and a technique for measuring availability have been studied. The system contains, in dispersion, metal oxide nanoparticles. A first part of the study focuses on the physical and chemical characterization of synthetic dispersions of nanoparticles. This part examines the effect of environmental conditions (pH, salinity, organic matter content, etc.) in the behavior of nanoparticles. Processes such as aggregation, solubilisation and sedimentation, are determined depending on environmental conditions. All these processes play an important role in the fate of nanoparticles in the environment and their toxicity. The second part of this thesis focuses on the application of the analytical technique DGT (Diffusive Gradient in Thin films) for measuring the flow of available metals in aqueous solutions. In the present study, the solubility of nanoparticles in aqueous dispersions has been determined. Moreover the DGT technique has been studied from a physical-chemical point of view. The contribution of the flux of complexes has been evaluated with a parameter, the lability degree, which takes into account the dissociation constants of the complexes and their diffusion. The accumulations of metals which in solution are present as dominant metal complexes electrically charged have been studied. If the charge is negative, the accumulation decreases with the decrease of the ionic strength and vice versa in the opposite case. This phenomenon is explained by the electrostatic repulsion between the negatively charged resin disk and the complex when it is partially labile. In conclusion, the resin seems to play a more active role than previously thought in the accumulation of metals in DGT.

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Zhang, Lingling. "Antimicrobial behaviour of suspensions of ZnO nanoparticles towards Escherichia Coli." Thesis, University of Leeds, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487794.

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Antibacterial agents are of relevance to a number of industrial sectors including medical, healthcare, food and environment. Organic antibacterial agents kill or inhibit the growth of bacteria by interrupting the synthesis of protein, lipid, nucleic acids or the integrity of the bacterial membrane. Heavy metals and metal oxides have a long application history in inhibiting the growth of bacteria.

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Souici, Abdelhafid. "Etude des propriétés optiques et structurales de nanoparticules de ZnS et PbS induites par radiolyse." Paris 11, 2009. http://www.theses.fr/2009PA112066.

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Cette étude traite des nanoparticules semiconductrices de ZnS et PbS synthétisées par radiolyse d’une solution contenant du thiol (RSH) et des ions Zn²⁺ ou Pb²⁺. Les propriétés optiques et structurales de ces nanoparticules ont été étudiées en fonction de différents paramètres, tels que la dose et le débit de dose d’irradiation, la concentration des précurseurs et le pH du milieu. Des nanoparticules de ZnS de taille comprise entre 0,9 et 2,2 nm ont été formées suite à l’irradiation d’une solution de pH ≈ 7. La possibilité de contrôler les dimensions de ces nanoparticules en faisant varier la dose permet de moduler leurs propriétés optiques. Un important effet quantique de taille a ainsi été observé sur le spectre d’absorption UV visible des nanoparticules de ZnS. Les spectres de fluorescence montrent une émission dans l’ultraviolet (350-450 nm). Les nanoparticules de PbS, formées sous irradiations à pH ≈ 4, ont une taille comprise entre 9 et 45 nm et possèdent des bandes excitoniques dans le proche infrarouge. Les bandes d’absorption et de fluorescence observées dans l’ultraviolet et le visible sont dues à la formation de nanoparticules de (PbS)n en présence du complexe (Pb²⁺ - RSH). Les mesures de rendements radiolytiques de formation des nanoparticules de (ZnS)n et de (PbS)n montrent l’effet de la fonction alcool (-OH) du thiol sur les mécanismes de formation. Les nanoparticules sont formées avec un rendement de G ≈ 3 x 10⁻⁷ mol J⁻¹ proche à celui de l’électron solvaté
The present study examines the ZnS and PbS semiconductor nanoparticles synthesized by radiolysis of solution containing the thiol (RSH) and the ions of zinc (Zn²⁺) or of lead (Pb²⁺). The optical and structural properties of these nanoparticles have been analysed according to different parameters such as: dose, dose rate, concentrations of the precursors and pH solution. The ZnS nanoparticles with size ranged between 0,9 and 2,2 nm have been generated after irradiation. The control of the nanoparticles size allows not only the observation of the quantum size effect but also the command of their optical properties (350 – 450 nm). However, the PbS nanoparticles formed under irradiation of solution pH ≈ 4 characterized by excitonics bands in the near infrared have a size between 9 and 45 nm. The absorption and fluorescence bands observed in the ultraviolet and the visible ranges are due to the formation of nanoparticles of (PbS)n in the presence of the complex (Pb²⁺ - RSH). The radiolytic formation yield of (ZnS)n and of (PbS)n nanoparticles shows the effect of the alcohol function(-OH) of the thiol on the mechanism of formation. The nanoparticles of (ZnS)n are formed with radiolytic yield of G ≈ 3 x 10⁻⁷ mol J⁻¹ close to the one solvated electron

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Raevskaya, A. E., Ya V. Panasiuk, O. L. Stroyuk, S. Ya Kuchmiy, V. M. Dzhagan, A. G. Milekhin, N. A. Yeryukov, et al. "Spectral and luminescent properties of ZnO–SiO2 core–shell nanoparticles with size-selected ZnO cores." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-161737.

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Deposition of silica shells onto ZnO nanoparticles (NPs) in dimethyl sulfoxide was found to be an efficient tool for terminating the growth of ZnO NPs during thermal treatment and producing stable core–shell ZnO NPs with core sizes of 3.5–5.8 nm. The core–shell ZnO–SiO2 NPs emit two photoluminescence (PL) bands centred at [similar]370 and [similar]550 nm originating from the direct radiative electron–hole recombination and defect-mediated electron–hole recombination, respectively. An increase of the ZnO NP size from 3.5 to 5.8 nm is accompanied by a decrease of the intensity of the defect PL band and growth of its radiative life-time from 0.78 to 1.49 μs. FTIR spectroscopy reveals no size dependence of the FTIR-active spectral features of ZnO–SiO2 NPs in the ZnO core size range of 3.5–5.8 nm, while in the Raman spectra a shift of the LO frequency from 577 cm−1 for the 3.5 nm ZnO core to 573 cm−1 for the 5.8 nm core is observed, which can indicate a larger compressive stress in smaller ZnO cores induced by the SiO2 shell. Simultaneous hydrolysis of zinc(II) acetate and tetraethyl orthosilicate also results in the formation of ZnO–SiO2 NPs with the ZnO core size varying from 3.1 to 3.8 nm. However, unlike the case of the SiO2 shell deposition onto the pre-formed ZnO NPs, individual core–shell NPs are not formed but loosely aggregated constellations of ZnO–SiO2 NPs with a size of 20–30 nm are. The variation of the synthetic procedures in the latter method proposed here allows the size of both the ZnO core and SiO2 host particles to be tuned
Dieser Beitrag ist aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

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Byl, Céline. "Synthèse et caractérisation de nanocomposites à base de ZnO pour des applications thermoélectriques." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112045/document.

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Ce travail de thèse a pour objectif l’obtention de nanocomposites denses ZnO/SiO2 afin d’améliorer les propriétés thermoélectriques de l’oxyde de zinc. Ce manuscrit décrit différents aspects de l’élaboration tant en terme de synthèse que de densification de nanocomposites ZnO/SiO2 ainsi que leur caractérisation. Afin d’obtenir des nanoparticules en grande quantité, de bonne cristallinité et de taille inférieure à 10 nm, l’optimisation d’une synthèse par voie polyol en jouant sur différents paramètres (pH, température, taux d’hydrolyse, solvant, surfactant) a été réalisée. Nous avons pu mettre en évidence l’intérêt d’utiliser l’acide benzoïque comme surfactant pour éviter l’agglomération de ces nanoparticules. La modification de surface des nanoparticules par de la silice a ensuite été explorée. Cette modification a été réalisée par une méthode classique, le procédé Stöber, ainsi que par une technique moins conventionnelle, l’ALD. Une étude approfondie de la densification par SPS à la fois de l’oxyde de zinc et des nanoparticules recouvertes a été décrite. L’influence de la couche amorphe déposée sur la croissance cristalline des nanoparticules a été démontrée. Nous avons par ailleurs pu mettre en exergue une pollution importante par du carbone lors de la densification des composés entrainant des modifications importantes des propriétés de transport. Le résultat majeur de cette thèse est la mise en évidence de clusters d’oxyde de zinc fortement dopés dans ces composés qui remet en question les mécanismes de transport dans le ZnO
This study is focusing on the synthesis of nanocomposites of Al doped ZnO/SiO2 with high density in order to increase the thermoelectric properties of ZnO. This work describes the optimization of the synthesis by investigating the effect of different experimental parameters (temperature, type of surfactant, degree of hydrolysis, nature of the solvent, pH) to obtain large amount of nanoparticles with size below 10 nm and good crystallinity. We have identified that using benzoic acid as surfactant could avoid the formation of particle aggregates. The modification of nanoparticles surfaces with SiO2 was investigated by using two methods the Stöber process and ALD. The possibility of ZnO and nanocomposite powder densification by spark plasma sintering was also tackled as well as the role played by the main parameters of the method (applied pressure and the best moment of its application, heating rate). The influence of the amorphous shell on the limiting grain growth during the sintering was demonstrated. Furthermore, a carbon accumulation which modifies the thermoelectric properties in the densified pellet was demonstrated. The source of it was assigned in part to the densification process. The most significant result of this study was the finding of the presence of ZnO clusters strongly doped wich could have fundamental implications as it may reopen the discussion on the transport mechanism in ZnO

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Acuautla, Meneses Monica Isela. "Development of ozone and ammonia gas sensors on flexible substrate." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4337/document.

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L'émergence des nouvelles applications dans le domaine de la micro et nanotechnologie requière de faibles coûts de fabrication et la caractérisation de dispositifs électroniques ayant des propriétés telles que la flexibilité, la portabilité, la légèreté, et des matériaux de faibles coûts. Les méthodes traditionnelles de fabrication impliquent de longues étapes de production, et des procédés de fabrication impliquant des étapes avec des produits chimiques. Le but de cette thèse est d'étudier la conception et la caractérisation de capteurs d'ammoniac et d'ozone sur support souple fabriqués par des processus de photolithographie et de gravure laser. Le support flexible est composé de Kapton avec des électrodes interdigitées de Ti/Pt pour la détection de gaz et un microchauffage. Les motifs du circuit ont été réalisés par photolithographie et gravure laser. L'utilisation de gravure laser sur support souple permet de réduire les coûts liés au temps de fabrication, aussi représente une excellente alternative aux processus chimiques. Des nanoparticles de ZnO déposées par gouttes ont été utilisées comme matériaux sensibles en raison de leurs excellentes propriétés dans la détection de gaz. Les conditions de détection de gaz ont été étudiées pour différentes concentrations d'ozone et d'ammoniac. Afin de tester une méthode de dépôt utilisée dans la production industrielle à grande échelle, un dépôt par spray ultrasonique a été effectué. Les capteurs réalisés montrent une large gamme de détection de 5 ppb à 500 ppb à 200 °C pour l'ozone et de 5 ppm à 100 ppm à 300 °C pour l'ammoniac avec une bonne reproductibilité, stabilité et de rapides temps de réponse et de retourn
Nowadays the emerging of new applications in the micro and nanotechnology field required to reduce fabrication costand to improve electronic devices with properties such as flexibility, portability, lightweight, and low cost. Traditional methods involve expensive and long production steps, and chemical vapor deposition. The purpose of this work is to present the conception and characterization of flexible ammonia and ozone sensors fabricated by photolithography and laser ablation processes. The flexible platform is composed of Kapton substrate with interdigitated Ti/Pt electrodes for gas detection and a micro-heater device. The circuit patterns were realized by photolithography and laser ablation. Photolithography is a well-known and reliable patterning process used on rigid substrate. The application of laser ablation process not only reduces fabrication time, but also represents an excellent viable alternative instead of chemical processes. ZnO thin films deposited by drop coating have been used as sensitive materials due to their excellent properties in the gas detection. The gas sensing condition and the performances of the devices are investigated for ozone and ammonia at different gas concentrations and different thin film thicknesses. In order to test a deposit methodology used in large scale industrial production, an ultrasonic spray deposition was done. The sensor provides a wide range of detection from 5 ppb to 500 ppb for ozone and from 5 ppm to 100 ppm for ammonia. Their best sensibilities were obtained at 200°C for ozone and 300 °C for ammoniac with good repeatability, stability and fast response/recovery time

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Hancock, Jared M. "Formation and Analysis of Zinc Oxide Nanoparticles and Zinc Oxide Hexagonal Prisms and Optical Analysis of Cadmium Selenide Nanoparticles." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3867.

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In this dissertation, methods to synthesize ZnO are reported. First, zinc oxide nanoparticles were synthesized with small amounts of transition metal ions to create materials called dilute magnetic semiconductors (DMS). We employed a low temperature sol-gel method that produces ZnO nanoparticles of reproducible size and incorporates cobalt, nickel, and manganese ions into the nanoparticles. Conditions were controlled such that a range of amounts of Co, Ni, and Mn were incorporated. The incorporation was tracked by color changes in the white ZnO powder to blue for Co, green for Ni and yellow for Mn. XRD measurements showed the nanoparticles were on the order of 10 nm in diameter and had a wurtzite structure. Magnetic measurements showed a change from diamagnetic to paramagnetic behavior with increasing concentration of metal dopants. Second, formation of ZnO single crystal hexagonal prisms from a sol-gel method is presented. The method required water, zinc acetate, and ethanolamine to create a gel of zinc hydroxide and zinc hydroxide acetate, which upon heating formed single crystal hexagonal prisms. Characterization of the gel was done by XRD as well as XRD high temperature chamber (HTK) to determine the role of temperature in prism formation. SEM images showed hexagonal prisms were of uniform size (0.5 × 2 µm.) TEM and electron diffraction images showed a change from randomly oriented particles to an ordered single crystal after heating. Water and the acetate salt of zinc proved to be critical to prism formation. Lastly, we report absorption and fluorescence properties of synthesized oligothiophenes and oligothiophene-ruthenium complexes that are bound to CdSe nanoparticles. Their ability to act as sensitizers and charge transfer junctions was tested. It was found that fluorescence of CdSe nanoparticles was quenched when they were bound to the oligothiophenes, and that the fluorescence of the oligothiophenes was also quenched. The fluorescence lifetimes of the quenched species were shortened.

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Jiang, Yunhong. "Antimicrobial behaviour of Polyvinyl Chloride(PVC) films coated with ZnO nanoparticles." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.545697.

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Ibrahem, Mohammed A. "Multiwavelength photoconductivity of ZnO nanoparticles based on surface defects and plasmonics." Thesis, University of Hull, 2017. http://hydra.hull.ac.uk/resources/hull:16599.

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ZnO is distinguished as the semiconductor of choice in a variety of applications such as in optoelectronics and photodetectors owing to its superior light sensitivity, the ease of synthesis in a wide range of nanostructure forms and its tuneable optical and electrical properties. Herein, ZnO photoconductivity is investigated for two purposes; firstly, to assess device stability with different preparation conditions and environments and secondly, to improve and extend photodetection of ZnO into the visible and near-infrared by stimulating surface defects and plasmonics effect. Persistent photoconductivity resulting from UV irradiation of ZnO NP films is highly affected not only by oxygen adsorption but also by other organic species and water in atmospheric air. The stability of ZnO photodetector is found to be enhanced in terms of current magnitude and sustainable photocurrent cycles when the device is prepared, annealed and tested in a nitrogen environment. A noticeable difference is identified in the ZnO NP surface composition, represented by surface organic complexes when the film is prepared and annealed in air compared to nitrogen. The aforementioned species are found to be removed efficiently in oxidized fabrication environment such as in air while partially decomposed in nitrogen. This enables the ZnO surface to build new organic species and surface carbonates by electrochemical reaction with atmospheric CO2 leading to promote electrically active defects surface states. Narrow-band photoconductivity, with a spectral width of 0.16 eV, is obtained by irradiating ZnO NP films using green light. A new model involving electron transfer from deep defects to discrete shallow donors is introduced to explain the narrow spectrum and the exponential form of the current rise and decay transients. The green photocurrent responsivity can be enhanced by storage in air and this correlates with the formation of carbonate surface species by the capture of carbon dioxide during storage. We successfully demonstrated a solution-processed ZnO NP photodetector using a low-cost and scalable photolithographic approach to fabricate dual (ultraviolet and green) and single (ultraviolet only) wavelength detecting ZnO pixels on the same substrate using the same mask. We also show that the plasmonic effect can be used to extend the photoconductivity of ZnO NPs into the deep red/infrared spectral region utilizing gold nanoislands as a light absorber and source of hot electrons in a vertical device configuration involving PEDOT: PSS.

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Shahmoradi, B., and A. Mateki. "Surface modification of ZnO and Ti02 nanoparticles under mild hydrothermal conditions." Thesis, Sumy State University, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20866.

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There are various techniques for synthesizing different Nanoparticles depending upon the desired properties, application, etc. One of these widely applied techniques is Hydrothermal. However, this technique is known for bulky materials and fabrication of nano-scale materials requires adopting some strategies to alter the properties of materials synthesized. We developed surface modification for this drawback. Application of surface modifier, or surfactant, or capping agent, or organic ligands in proper concentration could not only change morphology, reduce particle size, but also change the surface chemistry of the nanoparticles fabricated. The ZnO and TiO2 nanoparticles were modified using n-butylamine and caprylic acid as surface modifier under mild hydrothermal conditions (p= autogenous, T= 150-250°C, and t= 18 h). The nanoparticles modified were systematically characterized using Powder XRD, FTIR, SEM, zeta potential, and BET surface area. The characterization results revealed that nanoparticles have small size range, low agglomeration and highly stable. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/20866

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Londono, Zuluaga Nathalia. "Impacts of engineered nanoparticles (TiO2, ZnO, Ag) on aquatic microbial communities." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/1858.

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The production and uses of engineered nanoparticles (ENPs) have been increasing with the expansion of science and technology, and their unavoidable disposal into the soil and waterways, eventually ended up in the ocean causes serious concerns about their potential hazards to the environment and human health. The need to comprehend the impacts of ENPs in our aquatic ecosystem has motivated this research to study: 1) effect of TiO2 on Crypthecodinium cohnii; 2) effects of TiO2 and ZnO on an aquatic microbial community simulating a static lake environment; and 3) effects of TiO2, ZnO and Ag on a microbial community simulating those in a river after receiving treated wastewater. The results showed for the first study that TiO2 at different concentrations (50 mg/L, 30 mg/L, 10 mg/L, 2 mg/L, 0.5 mg/L, and 0 mg/L) in a 10-day period of observation did not negatively affect either cell growth, substrate (glucose) utilization, cellular composition or lipid profile of C. cohnii. On the contrary, the size distribution and zeta potential of TiO2 demonstrated that at its highest concentration (50 mg/L), it might present an effect on the microalgae. However, there was not enough evidence to prove toxicity, since all of the other analysis performed confirmed no impact. The second experiment proved that TiO2 and ZnO had different effects on an aquatic microbial community at experimental dosages including river water without ENP addition, TiO2 at a final concentration of 700 µg/L, ZnO at 70 µg/L, and both TiO2 and ZnO at 700 µg/L and 70 µg/L, respectively. TiO2 alone had no effect on the relative abundance of bacterial species, but caused significant decrease and increase of the relative abundances of the Chlorophyte and Streptophyta phyla, respectively, compared with other treatments and controls. ZnO, both alone or together with TiO2, brought increased population within the phylum of Bacteroidetes and decreased population of three species: Mycobacterium riyadhense, Hyphomicrobium spp., and Verrucomicrobium spp. Taken as a whole, the interaction between TiO2 and ZnO was not significant in terms of each ENP’s physicochemical properties and toxicity toward the target microbial community. The third and last study investigated individual and combined effects from three ENPs: TiO2 (700 µg/L – 7,000 µg/L), ZnO (70 µg/L - 700 µg/L) and Ag (200 µg/L – 2,000 µg/L). ENPs at these doses were found to be impactful to the target bacterial community. Similarly, the Eukaryota kingdom was affected by the ENPs at all tested concentrations. Overall, this thesis established that parameters for studying ENPs such as dosage, primary particle size, light effect, exposure time, and species should be taken into considerations to assess their impacts due to their unique physical and chemical properties.

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Zhu, Yao. "ZnO nanoparticles as a luminescent down-shifting layer for solar cells." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0090/document.

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Le but de cette thèse était de concevoir des matériaux à base de nanoparticules de ZnO qui puissent être utilisés de manière efficaces comme couche de down-shifting sur la face avant des cellules solaires photovoltaiques. Le défi principal a donc été d’obtenir des nanoparticules de ZnO avec un rendement de photoluminescence (PL QY) aussi élevé que possible. Diverses méthodes ont été et comparées utilisées pour la synthèse de nanoparticules de ZnO. Nous avons en premier lieu étudié des particules synthétisées par voie physique (le dépôt par jet d’agrégats de basse énergie, LECBD). Les particules résultantes démontrent une faible PL QY. Nous avons par la suite étudié des particules commerciales qui se sont comportées comme celles issues de la LECBD. Par conséquent, nous ne les avons pas retenues. Enfin, nous nous sommes concentrés sur des particules produites par voies chimique humide: la co-précipitation de l’acétate ou du sulfate de zinc en présence d’hydroxyde alcalin. Pour chaque cas, les paramètres de synthèses ont été variés pour optimiser les propriétés optiques en vue de l’effet de down-shifting. Avec un choix approprié de la nature (Li+) et de la quantité d’ions alcalins, le PL QY a été accru à 13 %. Nos résultats reproduisent l’état de l’art concernant cette technique. Cependant, la technique par hydrolyse s’est révélée bien plus intéressante. La seule réaction d’hydrolyse n’a pas initialement conduit à des particules très brillantes. Nous avons donc proposé une approche originale : l’ajout d’un acide faible, l’acide polyacrylique (PAAH), durant la synthèse. Alors que le PAAH a déjà été utilisé comme agent passivant de la surface de ZnO, son utilisation pendant la synthèse n’a jamais été tentée. Notre travail montre que en contrôlant la quantité et le poids moléculaire (longueur de chaine) du PAAH introduit pendant la croissance, un nanocomposite hybride très efficace à base de nanoparticules de ZnO et de PAAH peut être obtenu, avec un PL QY aussi élevé que 20 %. En mélangeant le PAAH avec son sel de sodium, PAANa, le nanocomposite présente un PL QY record de 50%, qui augmente jusqu’à 70 % après un mois. Les raisons physico-chimiques de cet accroissement sont discutées dans le manuscrit. Nos explications pointent vers un effet combiné de la taille, de la morphologie et de la composition. Dans la partie suivante, des nanoparticules de ZnO pouvant être dispersées dans l’eau ont été obtenues avec succès tout en maintenant leur rendement quantique entre 20 % et 34 % ; ce en utilisant un mélange de PAAH/PAANa de ratio volumique, de concentration et de volume réactionnel optimaux. Nous insistons sur la nécessité d’obtenir un compromis entre une bonne capacité de dispersion et un fort PL QY. Cette partie de la thèse pave la voie vers des applications industrielles ultérieures.Finalement, l’effet de down-shifting des nanoparticules luminescentes de ZnO a été simulé pout déterminer le gain potentiel de rendement de cellules photovoltaïques
In this thesis, we aim at designing mechanically stable ZnO nanoparticle based materials as a luminescent down-shifting layer that can be processed on a scalable amount and deposited on standard solar cells at a reduced cost. The main challenge was thus to get ZnO nanoparticles with as high photoluminescence quantum yield (PL QY) as possible. Different methods have been used and compared to synthesize ZnO nanoparticles. We have first studied particles synthesized by a physical route (the Low Energy Cluster Beam Deposition relying on the adiabatic expansion of a plasma). The resulting particles did not exhibit a PL QY high enough to be interesting for down-shifting. We next investigated commercial particles which behaved as the LECBD ones. We consequently discarded them. Eventually, we concentrated on nanoparticles produced by wet chemistry. Two routes were explored: the conventional co-precipitation method of Zn acetate or sulfate in presence of an alkaline hydroxide and the hydrolysis of ZnEt2. For both cases the synthesis parameters have been tuned to optimize the optical properties for down-shifting process. When appropriately choosing the alkaline ion (Li+ instead of K+) nature and amount, the PL QY has been increased to 13 % in the co-precipitation method. Our results reproduce the state-of-the-art knowledge concerning this technique. The hydrolysis route proved to be even more interesting. The sole hydrolysis reaction did not lead to very bright particles. We have thus proposed an original strategy: the addition of a weak acid, the polyacrylic acid (PAAH) during the synthesis. If PAAH has been used previously as a passivating capping agent of ZnO, its use during the synthesis has never been tempted. Our work shows that by tuning the amount and molecular weight (chain length) of PAAH introduced during the synthesis, a very efficient hybrid nanocomposite consisting of ZnO nanopaerticles in a PAAH matrix can be obtained with PL QY as high as 20 %. When mixing PAAH to its sodium salt PAANa, the nanocomposite exhibits record values of PL QY of 50 %, increasing to 70 % over a month. The physico-chemical reasons for this enhancement are discussed in the manuscript. Our explanations point to a combined effect of the size, morphology and composition. In the subsequent part, ZnO NPs dispersible in water have been successfully achieved while maintaining their PL QY high, between 20 % - 34 %, using a PAAH/PAANa mixture at the optimal volume ratio, concentration, lengths and volume. We highlight the need to get a compromise between a good dispersibility and a high PL QY. This part of the thesis paves the way for the further industrial applications. Finally, the down-shifting effect of luminescent ZnO nanoparticles on solar cells has been simulated to obtain a potential enhancement of solar cell efficiency by the ZnO NPs down-shifting layer

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Tan, Soon-Seng, and 陳順成. "The synthesis and characteristics of ZnS and ZnO nanoparticles." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/26626104846406917985.

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碩士
國立成功大學
電機工程學系碩博士班
92
Zinc sulfide (ZnS) and Zinc oxide (ZnO), as II-VI semiconductors with a wide band gap energy of 3.68 eV and 3.35 eV respectively, have received much attention due to their excellent luminescence properties and commercially used as phosphors applicated in electroluminescence devices. They are candidate materials for phosphors that emit visible light. The major and important applications of phosphors are used as light sources, display devices, radiation detectors and so on. 　　In this report, we use low temperature solid-state synthesis and chemical precipitation method to prepare ZnS, ZnO and ZnS doped Mn2+ nanoparticles. The nanoparticles were characterized by X-ray diffraction (XRD), photoluminescence (PL) spectroscopy, differential thermal analysis (DTA), high-resolution analytical electron microscopy (HR-AEM), energy dispersive spectrometer (EDS), CIE chromaticity diagram, impedance analyzer (HP-4294A) and Raman spectrum. By means of various experiment parameters to find out the preferred synthesis conditions. 　　From the experiment results, the PLE spectrum exhibits a blue shift due to quantum confinement effect. The dimension of particles and the ratio of Zinc and Sulfur in the ZnS matrix affect the PL intensity. By adding 1 mol% Mn2+ ion, it shows the maximum emission intensity. A green emission peak at 501 nm was observed in PL spectrum of ZnO nanoparticles. In our experiment, we have successfully obtained the phosphor fabricated at low tempereture emits near-white color.

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Chen, Hui-Wei, and 陳慧薇. "Synthesis of ZnS and Mn-doped ZnS nanoparticles and its photoluminescence." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/87899132794837961550.

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Mnqiwu, Khumblani. "ZnS and CuxSy nanoparticles from dithiocarbamate ligands." Thesis, 2017. http://hdl.handle.net/10352/428.

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M.Tech (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology.
Dithiocarbamate ligands and their complexes has been a subject of interest in various fields but they found much interest in medical applications as potential anti-microbial agents. The dithiocarbamate ligands were used to prepare complexes of copper and zinc. All the prepared ligands and complexes were characterized using techniques such as IR and 13CNMR spectroscopy and thermogravimetric analysis (complexes). The data obtained from the spectroscopies was consistent with the coordination of the ligand to the metal ion through the sulfur atoms of the dithiocarbamate or thioureide moiety. The thermal analysis of the prepared complexes gave a final residue of metal sulfide, thus indicating the potential of the prepared complexes as single molecular precursor for the synthesis of metal sulfide nanoparticles. The prepared complexes were then used to synthesize metal sulfide nanoparticles. The nanoparticles were successfully prepared by thermal decomposition of a single-source precursor (dithiocarbamate complexes) in a solution of hexadecylamine (HDA) or tri-n-octylphosphine oxide (TOPO). The investigated parameters were the capping molecule (HDA and TOPO), and capping molecule concentration (3 g and 6 g) to see their effect on the shape and size of the synthesized nanomaterials. The synthesized metal sulfide nanoparticles were characterized using techniques such as UV-vis spectroscopy, photoluminescence spectroscopy, X-ray diffraction analysis and transmission electron microscopy. The absorption study showed some interesting features in the prepared nanomaterials. The first was the red-shifted spectra of the ZnS nanoparticles which was attributed to the impurities and that assumption was further confirmed by the XRD analysis that showed a sulfur impurity and other amorphous peaks. The second was the localized surface plasmon resonances on the copper sulfide nanoparticles that suggested the formation of electron deficient copper sulfide stoichiometry that was further confirmed by XRD analysis that gave hexagonal phase copper sulfide covellite. The TEM images of the prepared nanoparticles showed that the concentration and the capping molecule has an effect on the size and shape of the synthesized nanoparticles. The increase in capping concentration gave a decrease in particle size in most of the prepared nanoparticles, while they were few exceptions. The capping molecule effect showed that most of the nanoparticles prepared from TOPO were spherical in shape and were well dispersed compared to the mixed morphological nanoparticles prepared from HDA. There were also exceptions of the well dispersed HDA-capped nanoparticles.

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Ignawati, Sifera, and 葉美慧. "Optical and Structure Characterization and Synthesis of CdS/ZnS and ZnS/CdS core shell nanoparticles." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/80966331346304532178.

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碩士
國立成功大學
化學工程學系碩博士班
97
CdS and ZnS core nanoparticles were synthesized by microwave method and then coated with shell material by traditional method, using simple and safe reagents such as cadmium acetate, zinc acetate, and thiourea to synthesis the core shell nanopartices. After coating CdS core by ZnS shell the photoluminescence intensity greatly increase from 18 a.u to a maximum photoluminescence intensity of 225 a.u. For ZnS/CdS core shell nanoparticles, after CdS coated on ZnS core, the photoluminescence intensity increases significantly too, the bare ZnS cores have a photoluminescence intensity of 353 a.u and the ZnS/CdS core shell nanoparticles can reach a maximum photoluminescence intensity of 1460 a.u. Shell formation was confirmed by observation of a red shifting in the photoluminescence spectra. As the precursor feeding rate decreases, it leads the formation of bigger core shell nanoparticles, and so does the increases of precursor concentration. The advantage of the process is that it can be carried out in the open air using simple equipment and is simpler, cheaper, and safer as compared with another method.

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Gao, Yu-Jia, and 高于迦. "Preparation and Luminescence Properties of Manganese Doped ZnS Nanoparticles." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/35804545404981806649.

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Abstract:

碩士
大同大學
材料工程研究所
89
We choose ZnS as host material in this study because of its excellent photoelectric property, and adding Manganese element of different concentration as activator. Co-precipitation method is used to prepare manganese doped zinc sulfide nanocrystal, and PL analysis is performed to realize the change of PL property made by different manganese concentration and heat treatment. Also, the effect of nanosize to sample is discussed. The recombination energy of electron-hole pairs in ZnS crystal transfer to Mn2＋ ion, causing it to emit characteristic spectra. This yellow spectra of bulk ZnS:Mn observed in photoluminescence has peak at 585nm (2.12 eV), and this is associated with the 4T1→6A1 transition of Mn2＋ ion in 3d orbit. The sample that 1% Mn doped has a λem of 592nm, and theλem shifts to 600nm when the concentration of Mn doped increases to 5%. Comparing to common bulk ZnS:Mn, the λem of ZnS:Mn nanocrystal we made shifts to longer wavelength. When the particle size decreases to nanosize, the effect of crystal field to each ion will decrease. Also, as a result of quantum confinement, the electron transition orbit changes so that the emitting wavelength shifts. Nanosize not only makes emission wavelength shift to longer wavelength area but also causing the excitation wavelength λex changes with particle size; if the size of particle become smaller, the λex shifts to higher energy area. We can know from FTIR and PL spectra that heat treatment temperature of 200℃ doesn’t almost do no changes to our sample, but 300℃ and 400℃ make sample having higher luminous strength. This result is due to the organic substance like C=O and COO－ in sample powder before heat treatment, and the organic substance affects absorption and transfer process of energy so that 300℃ and 400℃ heat treatment make sample having higher luminous strength by decreasing organic substance. But sample with 5% Mn heat treated to 400℃ has lower luminous strength than 300℃; this is due to the result of concentration quenching.

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46

Huang, Chia-Ching. "Studies of magneto-optical properties of CdTe/CdSe/ZnS multilayer nanoparticles." 2008. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-0502200817375000.

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47

Huang, Chia-Ching, and 黃家慶. "Studies of magneto-optical properties of CdTe/CdSe/ZnS multilayer nanoparticles." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/13504253023348323757.

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碩士
臺灣大學
物理研究所
96
Although the absolute phase of a quantum state is not measurable, the relative phase of a coherent charged particle wave could be manipulated. In the famous Aharonov-Bohm effect for an electron traveling in a ring, interference pattern was observed with changing magnetic flux. Recently, optical Aharonov-Bohm has received much attention. The effect of the relative phase of the electron and hole in a magnetic field on the excitonic properties in semiconductors was studied theoretically and oscillation of the excionic energy and quenching (or oscillation) of the integrated photoluminescence intensity with magnetic field were predicted. Experimentally, evidence of the optical Aharonov-Bohm effect was observed with negatively charged exciton in InGaAs/GaAs quantum ring and polarized exciton in type-II GaAs-GaSb system. In this thesis we’ll present our studies on the optical Aharonov-Bohm in CdTe/CdSe/ZnS system. The nanoparticles were grown by chemical method and have size of about 6 nm and the band alignment between the core (CdTe) and the shell (CdSe) is a type–II band alignment. The addition of ZnS layer is to passivate the surface of CdSe and to enhance the light emitting efficiency. Magneto-photoluminescence experiment was performed at T=1.4 K with a 14 T superconducting magnet in conjunction with a green diode laser and a monochromator. Oscillation on the peak energy of the photoluminescence spectra as well as oscillation in the integrated intensity as a function of magnetic field were observed and are attributed to the optical Aharonov-Bohm-like effect.

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48

Chuang, Ya-Ting, and 莊雅婷. "Photochemical Assisted Method in Decoration of Au Nanoparticles on ZnS and ZnSe Crystal for Surface-enhanced Raman Scattering Measurement." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/28t33j.

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碩士
國立中興大學
化學系所
106
Surface-enhanced Raman scattering (SERS) is a powerful means for chemical analysis. This SERS effect can be observed when target molecules adsorbed or nearby metal nanoparitcles with a proper size and shape. To prepare active substrates for SERS measurements, ZnS and ZnSe crystals were selected as solid support in this work as they are commonly used optical windows, which exhibit photocatalytic ability with unique chemical properties. Methods based on electroless displacement and the assistance of photoreduction were developed to decorate SERS active gold nanoparticles (AuNPs) on the selected ZnS and ZnSe crystals. Several parameters, such as the concentration of reaction solution, the temperature of reaction, photo irradiation time, and the additive, were examined their contributions to the production of suitable AuNPs for SERS measurements. pHydroxythiophenol (pHTP) was used to probe the SERS performances for the prepared SERS substrates. After correlation of the observed Raman signals, the morphology of produced AuNPs by SEM with reaction parameters, mechanisms in production of AuNPs on ZnS and ZnSe were found significantly different. For produced AuNPs on ZnS crystal, AuxSy particles were formed rather than AuNPs, which degraded their SERS performances. On the other hand, when ZnSe crystals were used, Se atoms in the ZnSe crystals are capable to reduce the gold ions through formation of higher oxidation state of Se and hence, AuxSe particles formed on the surface of ZnSe is limited. On the other hand, SERS substrates based on ZnSe showed much better performances than that of ZnS. By tuning the reaction conditions, SERS substrates based on ZnS and ZnSe could be successfully prepared. Based on the optimized condition in preparation of SERS substrates, SERS intensity of pHTP on ZnS substrate was found an order weaker than that of ZnSe. In conclusion, a new method to prepare AuNPs on ZnS and ZnSe was successfully developed in this work and both the mechanism in formation and the impact of each parameter to the formation of AuNPs were well explored.

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49

Chang, Chih-Yuan, and 張志遠. "Advanced Nanodevice Structures with CdSe/ZnS and/or Au Nanoparticles for Photo-Sensing Applications." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/00272243905175103222.

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碩士
國立交通大學
電子工程系所
94
In this work, we used CdSe/ZnS (core/shell) and/or Au NPs to construct the multi-layered photo-sensing nanodevice structures on a silicon substrate through ionic interaction. ZnS with larger energy bandgap served as a passivation layer on CdSe NPs to enhance the stability and quantum yield. From the results of UV-visible absorbance and photoluminescence spectra, CdSe/ZnS NPs exhibit better optical properties than CdSe NPs in the previous work. For the four-layered nanostructure composed of CdSe/ZnS and Au NPs, there was constantly about 28 nA (30μm / 5μm) and 70 nA (30μm / 15μm) increment to the current measured in the dark for each voltage bias after illumination with 375 nm laser. In addition to 375 nm, 400 nm and 435 nm lasers were also used as light sources for photo-excitation. We found that more photocurrent was generated under shorter wavelength illumination, which was also verified in the absorption / emission spectra. Besides, more photocurrent was generated in the nanostructure with a longer length or a larger number of layers, which can be successfully explained by using the model of “nano-Schottky-diodes and resistor array”. We can obtain the same phenomenon as using HSPICE to simulate the two dimensional model. Finally, we found that the“photocurrent volume density (PVD)”of the 4-layered Au / AET-CdSe/ZnS nanostructure is at least 1183 times better than that of CdSe thin film structure. The power conversion efficiency can achieve 40% based on ourideal inference. In addition to nanodevice composed Au and CdSe/ZnS NPs, we constructed multi-layered structure on the silicon oxide substrate by using only CdSe/ZnS NPs. MSA-CdSe/ZnS and AET-CdSe/ZnS NPs, which were chemically modified prior to ionic assembly process, have negative-charged and positive-charged functional groups on the surface of the NPs respectively. We found that the PVD of the 12-layered structure is at least 34 times better than that of conventional CdSe thin film structure. Finally, we conclude that the Au / AET-CdSe/ZnS nanodevice acts like a photodiode while the MSA-CdSe/ZnS / AET-CdSe/ZnS nanodevice acts like a typical traditional photoresistor. Besides, the Au / AET-CdSe/ZnS nanodevice has enormous potential to turn into solarcells applications.

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50

Chia-ChingChu and 朱家慶. "The Excitation Spectroscopy of the NaD X-A Transitions and the Synthesis of ZnS Nanoparticles." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/80641357272505053670.

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