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Aldemir, Müge. "Metal oxide supported cadmium sulfide for photocatalytic synthesis of homoallylamines." [S.l.] : [s.n.], 2006. http://deposit.ddb.de/cgi-bin/dokserv?idn=978677617.
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Nouri, Hassan. "Erosion and electrode energy distribution in switches with silver-cadmium-oxide contacts." Thesis, University of Plymouth, 1990. http://hdl.handle.net/10026.1/2391.
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The cathode and the anode fall of the DC arcs are measured by fast oscilloscope for Ag-CdO contacts over a range of gap-lengths from 0.05 mm to 1 mm, and currents of 4-10 Amps at atmospheric pressure, with a known electrode closing speed, using the Moving Electrode Method. It was observed that the anode fall can occur in a few places within the arc voltage waveform, and is dependent of the electrodes' surface condition. Both cathode and anode falls increase with gap-length and decrease with current. It was found that when arc length is shorter than electrode separation, discontinuity within the arc voltage waveform during closure is caused, in many cases, by vapourisation of the first point of contact or by a high electric field set up between the two electrodes. These discontinuities are named as Voltage Step Phenomena. These voltage steps are related to the cathode and anode fall voltages, and their regular occurrences are a function of surface roughness. The fluctuations in the arc voltage waveform are thought to originate mainly from the cathode. A technique has been developed to measure the temperature of the electrodes accurately by using a T-type thermocouple, 0.075 mm diameter, in conjunction with a DC amplifier with a gain of 247. The thermocouple is placed as close as possible under the electrode surface (200 µm). This enables the temperature of the contact to be measured, after breaking contact, for an arc-duration even as short as 1ms. The time-constant of the probe (contact containing the thermocouple) is measured to be approximately 18ms. With this technique the temperature of the electrodes are measured for currents and gap-lengths ranging 4-10 Amps and 0.05-1 mm respectively. The effect of contacts being new and change of polarity have been investigated. From these results it is concluded that the co-existence of layers of foreign material on one, or both, surfaces causes the temperature of the electrodes to be high for the first 50-100 operations, before reaching to steady-state conditions. Change of polarity suggests that the moving electrode, either anode or cathode, due to the effect of air movement over its surface, is cooled relative to when fixed. The power transfer to the electrodes is calculated for various currents and gap-length using thermal analogue formulae derived from the transient response of an RC circuit to a d.c. pulse. The results show that below 0.2 mm the sum of the anode and cathode power is approximately equal to the arc power, and hence losses are negligible. At around 0.125 mm, for currents of about 6A and 12A, they both receive an equal amount of power from the arc. This has been related to the thermal energy of the electrons being negligible, at such separation, at the anode end of the plasma column. The power balance equations are solved to calculate the positive ion current to the cathode, and the thermal energy of the electrons in the plasma column, under various test conditions. In the investigation of erosion, the S.E.M. studies show that most of the power dissipated on the surface of the electrodes is used in melting and evaporation. The x-ray analysis shows that the melted metal is composed mostly of Silver. To operate the test rig and collect the generated data automatically, a computerised test system, with a mini data acquisition system, has been designed and constructed here.
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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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Baran, Andre. "Chemical bath deposited zinc cadmium sulfide and sputter deposted [sic] zinc oxide for thin film solar cell device fabrication." [Gainesville, Fla.] : University of Florida, 2009. http://purl.fcla.edu/fcla/etd/UFE0022644.
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Chen, Youjiang. "Fundamental Aspects of Electrocatalysis at Metal and Metal Oxide Electrodes." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1284390270.
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Nadarajah, Athavan. "Fundamental Properties of Functional Zinc Oxide Nanowires Obtained by Electrochemical Method and Their Device Applications." PDXScholar, 2012. https://pdxscholar.library.pdx.edu/open_access_etds/633.
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We report on the fundamental properties and device applications of semiconductor nanoparticles. ZnO nanowires and CdSe quantum dots were used, prepared, characterized, and assembled into novel light-emitting diodes and solar cells. ZnO nanowire films were grown electrochemically using aqueous soluble chloride-based electrolytes as precursors at temperatures below 90° C. Dopants were added to the electrolyte in the form of chloride compounds, which are AlCl3, CoCl2, CuCl2, and MnCl2. The optical, magnetic, and structural properties of undoped and transition-metal-ion doped ZnO nanowires were explored. Our results indicate that the as-grown nanowire structures have considerable internal strain, resulting in clearly visible lattice distortions in bright and dark-field transmission electron micrographs. Photo and electroluminescence studies indicate that the strain-induced defects strongly dominate any dopant-related effects. However, annealing at moderate temperature as well as laser annealing induces strain relaxation and leads to dopant activation. Hence, the optical and electrical properties of the nanowires significantly improve, allowing these nanowires to become feasible for use in the fabrication of solar cell and LED devices. In addition, the magnetic impurities incorporated into our ZnO nanowires show superparamagnetic behavior at room-temperature, while Al-doped and undoped ZnO nanowires show no magnetic behavior. The electroluminescence (EL) is achieved from a vertical hybrid p-n junction LED arrangement consisting of a hole-conducting polymer and n-type ZnO nanowires, our group was the first to report this vertical nanowire-based LED in Könenkamp et al., 2004 [12]. The observed EL spectra show an ultraviolet excitonic emission peak and a broad defect-related emission band in the visible range. After annealing at 380° C, the defect related EL peak exhibits a characteristic shift to higher wavelengths, where the magnitude of the shift is dependent on the dopant type. Aluminum incorporation exhibited the most improved exciton related-emission, leading to the emergence of a narrow excitonic luminescence peak around 390 nm, which is close to the bandgap of ZnO. The comparison of spectra obtained from temperature-dependent photoluminescence (PL) measurements, before and after thermal annealing, also indicates that the optical activity of impurities changes noticeably upon annealing. The internal quantum efficiency for PL is measured to be as high as 16 percent for Al-doped samples annealed at 380° C. The PL measurements also show that the excitonic luminescence is preferentially guided, while the defect related emission is more isotropically emitted. The nanostructured heterojunction solar cell is designed such that thin CdSe quantum dot films are embedded between a ZnO nanowire film and a hole-conducting polymer layer. This arrangement allows for enhanced light absorption and an efficient collection of photogenerated carriers. Here, we present a detailed analysis of the pyridine solution and 1,2- ethanedithiol ligand exchange processes of the quantum dots, deposition processes of this quantum dot layer, the conformality of this layer on deeply nanostructured samples, and the effect of a surfactant-aided thermal annealing process. Annealing creates a structural conversion of the quantum dot layers into an extremely thin continuous poly-crystalline film, with typical grain diameters of 30-50 nm. This transition is accompanied by a loss of quantum confinement and a significant improvement of the charge transport in the CdSe layer. The combination of the solution and ligand exchange of CdSe quantum dots, as well as the deposition and optimized annealing processes of this quantum dot layer, resulted in solar cells with an open-circuit voltage up to 0.6 V, a short circuit current of ~15 mA/cm2, an external quantum efficiency of 70 percent, and an energy conversion efficiency of 3.4 percent. This 3.4 percent efficiency is presently one of the best efficiencies obtained for this type of device.
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PAGANINI, PAULA P. "Síntese e caracterização de trocadores iônicos inorgânicos a base de óxidos mistos estanho-titânio para utilização na recuperação de cádmio e níquel e estudos fotoluminescentes." reponame:Repositório Institucional do IPEN, 2007. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11575.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Zhao, Fenghuan. "Synthèse d'hétérostructures métal-semiconducteur par photodéposition laser." Thesis, Bordeaux, 2022. http://www.theses.fr/2022BORD0229.
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Un montage utilisant des cuvettes et des lasers UV et bleu comme sources de lumière a été construit pour effectuer la photodéposition de nanodots métalliques (NDs) sur des nanoparticules (NPs) de TiO2 et des nano-hétérostructures de type Janus de Cu2-xS-CuInS2 en solution aqueuse et organique respectivement. Trois types de NDs métalliques différents, à savoir Au, Ag, Pd, sont introduits en surface des NPs de TiO2, et des NDs d'Au sont déposés sur Cu2-xS-CuInS2. Plusieurs techniques, dont le TEM/HRTEM, la cartographie EDS et la spectroscopie UV-vis, sont utilisées pour caractériser la taille, la morphologie et la distribution des NDs métalliques. Les nanohétérodimères (NHDs) Au-TiO2 sont synthétisés avec succès ; un rendement de NHDs Au-TiO2 proche de 100% est obtenu en gérant la concentration des NPs TiO2 et du précurseur d'or. En particulier, le mécanisme d'adsorption du méthanol et du précurseur d'or sur le TiO2 pendant la photodéposition est étudié. En comparant les données expérimentales obtenues dans des microcanaux et des cuvettes, le modèle établi décrit le processus dynamique global de la croissance des NDs d'Au sur le TiO2, de la loi de croissance en t 1/3 à l'achèvement. La taille finale des NDs d’Au peut être prédite avec précision par le modèle, en particulier la fin de la croissance. De plus, des NPs d'Ag et de Pd d'autres métaux ont été déposées sur la surface de TiO2, et des NHDs d'Ag-TiO2 et de Pd-TiO2 ont également été synthétisés. Les effets du piégeur de trous, de la puissance du laser et du temps d'exposition sur la taille et la distribution des NDs métalliques sont étudiés. De plus, la croissance des NDs d'Ag et de Pd suit le modèle proposé pour la croissance de l'Au. Le projet est étendu à la photodéposition de NDs bimétalliques cœur-coquille où Au, Ag et Pd sont introduits sur des NHDs Au-TiO2 par une seconde étape de photodéposition, formant une structure cœur-coquille à la surface des NPs TiO2. Pour le système Au@Au core@shell, la coquille d'Au peut être contrôlée avec précision en faisant varier la concentration du précurseur d'or ; la taille et l'épaisseur du cœur et de la coquille d'Au correspondent à nos attentes. Pour le système Au@Ag, la coquille d'Ag obtenue est limitée à environ 1 nm d'épaisseur, ce qui résulte de la faible électronégativité de l'Ag (1,9) par rapport à l'Au (2,4). Pour le système Au@Pd, le Pd présente une croissance non isotrope sur le cœur d'Au, ce qui entraîne une coquille de Pd non uniforme en raison de l'important décalage de réseau entre Au et Pd. Enfin, des NDs d'Au sont introduits sur des hétéro-nanorods de Cu2-xS-CuInS2 par photodéposition dans le toluène avec un laser bleu. La nucléation et la croissance des Au NDs sont étudiées et la distribution géométrique (i.e., le nombre et la distribution) des Au NDs, ainsi que leurs tailles en réglant la puissance du laser, le temps d'exposition, les piégeurs de trous et la concentration des précurseursCuvette setup with UV and blue laser as light sources are built to perform photodeposition of metals nanodots (NDs) onto TiO2 nanoparticles (NPs) and Janus-typed Cu2-xS-CuInS2 nano-heterostructures in aqueous and organic solution respectively. Three different metal NDs, i.e., Au, Ag, Pd, are introduced on the surface of TiO2 NPs, and Au NDs are deposited on Cu2-xS/CuInS2. Several techniques, including TEM/HRTEM, EDS mapping, and UV-vis spectroscopy, are performed to characterize the size, morphology, and distribution of the metal NDs. Au-TiO2 nanoheterodimers (NHDs)are successfully synthesized and a close to 100% yield of Au-TiO2 NHDs is achieved by managing the concentration of TiO2 NPs and gold precursor.Especially, the adsorption mechanism of methanol and gold precursor on TiO2 during photodeposition is investigated. By comparing the experimental data obtained in microchannels and cuvette setups, the established model describes the overall dynamic process of Au ND growth on TiO2 from 1/3 growth state to completion. The final size of Au NDs can be accurately predicted by the model in particular the growth completion. In addition, other metal Ag and Pd NPs were deposited on the surface of TiO2, and Ag-TiO2 and Pd-TiO2 NHDs are also synthesized. The effects of the hole scavenger,laser power, and exposure time on the size, and distribution of metal NDs are investigated. Moreover, the growths of Ag and Pd NDs both follow the proposed model for Au growth. The project is extended to bimetallic core-shell NDs photodeposition and Au, Ag and Pd are introduced on Au-TiO2 NHDs by a second step photodeposition, forming a core-shell structure on the surface of TiO2 NPs. For the Au@Au core@shell, the Au shell can be precisely controlled by varying the gold precursor concentration and the size and thickness of the Au core and shell pretty much fit our expectations.For the Au@Ag system, the Ag shell obtained is limited to around 1 nm thickness which results from the low electronegativity of Ag (1.9) compared to other Au (2.4). For the Au@Pd system, Pd shows a non-isotropic growth on the Au core resulting in a nonuniform Pd shell due to the big lattice mismatch between Au and Pd. Finally, Au NDs are introduced onto Cu2-xS/CuInS2 heteronanorods by photodeposition in toluene with a blue laser.The nucleation and growth of Au NDs are studied and the geometric distribution (e.g., number and location) of Au NDs, as well as their sizes, can be well controlled by tuning laser power, exposure time, hole scavengers, and precursors concentration
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Natu, Gayatri. "Design and Synthesis of Metal Oxide Nanomaterials and Study of Their Electronic Properties for Energy Conversion via Dye-sensitized Solar Cells." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1343823995.
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Pons, Frédéric. "Electrical contact material arc erosion: experiments and modeling towards the design of an AgCdO substitute." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/33816.
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AgCdO is one of the most widely used contact materials in the world because of its outstanding performance. Nevertheless, due to environmental considerations, it will soon be completely forbidden by European environmental directives. Therefore, finding a good substitute is of crucial importance.
Electrical arc erosion plays a crucial role in the reliability and life of power switching devices. Depending on the contact material's behavior in response to an electrical arc, surface damage can induce severe changes in contact material properties that will impact the power switching device's functioning. Consequently, electrical arc effects and consequences on the contact material surface are of first importance.
In this context, we have focused our research activities on the following axes.
First of all, in order to better understand AgCdO (Current contact material in aerospace industry) and AgSnO₂(Potential candidate to AgCdO substitution) arc erosion behaviors, arc erosion experiments, where the power switching devices have been subjected to different numbers of arc discharges, have been realized.
Further, a general macroscopic electrical contact arc erosion model valid for low and high currents was developed. To compare model results to experimental data, this model describes the complete breaking process of electrical contacts and gives the total amount of material removed after one breaking operation. In parallel, arc erosion experiments on AgCdO power switching devices have been conducted at high currents (0
-> 1000 A) in order to validate the arc erosion model.
Next, using the general arc erosion model, the properties having the greatest
influence on the electrical arc erosion process have been determined through simulations
on silver contact material. At this stage, ab initio calculations were needed to obtain
ranges of variation of certain silver contact material properties.
Finally, an investigation of the trends of changing local contact material on these identified material properties was performed. This study composition of AgSnO₂was based on ab initio calculations for two different oxide compositions of AgSnO₂.
These will allow us to give directions to aid the design of a good substitute for AgCdO, and therefore, to complete the main objective of this research work.
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Yanamanagandla, Srikanth. "SYNTHESIS AND CHARACTERIZATION OF SCHOTTKY DIODES ON N-TYPE CdTe NANOWIRES EMBEDDED IN POROUS ALUMINA TEMPLATES." UKnowledge, 2008. http://uknowledge.uky.edu/gradschool_theses/573.
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This work focuses on the growth of vertically aligned CdTe nanowire arrays of controllable diameter and length using cathodic electro deposition in anodized alumina templates. This step was followed by annealing at 250° C in a reducing environment (95% Ar + 5% H2). AAO template over ITO-glass was used as starting template for the device fabrication. The deposited nanowires showed nanocrystalline cubic phase structures with a strong preference in [111] direction. First gold (Au) was deposited into AAO using cathodic electro deposition. This was followed by CdTe deposition into the pore. Gold was deposited first as it aids the growth of CdTe inside AAO and it makes Schottky contact with the deposited n type CdTe. CdTe was determined to be n-type from the fact that back to back diode was obtained with Au-CdTe-Au test structure. Aluminum (Al) was sputtered on the top to make the ohmic contact to the n type CdTe deposited in AAO. Analysis of Schottky diodes yielded a diode ideality factor of 10.03 under dark and 10.08 under light and reverse saturation current density of 34.9μA/cm2 under dark and 39.7μA/cm2 under light.
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Gutmann, Sebastian. "Electronic Structure Characterization of Nanocrystalline Surfaces and Interfaces with Photoemission Spectroscopy." Scholar Commons, 2011. http://scholarcommons.usf.edu/etd/3137.
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In this study, photoemission spectroscopy (PES) was used to investigate the electronic properties of nanocrystalline titanium dioxide (TiO2), zinc oxide (ZnO), and cadmium selenide (CdSe). Electrospray deposition technique enabled the preparation of thin films in vacuum from a dispersion prepared outside the vacuum chamber. This method also allowed the step-wise formation of interfaces and the monitoring of the evolution of the electronic structure with intermittent PES characterization. The work function of nanocrystalline TiO2 and ZnO was measured with ultraviolet photoemission spectroscopy (UPS) and low-intensity x-ray photoemission spectroscopy (LIXPS). Measurements on environmentally contaminated surfaces revealed an instantaneous and permanent work function decrease of 0.3-0.5 eV upon exposure to ultraviolet radiation during a UPS measurement. The work function reduction is likely to be related to the formation of a surface dipole caused by the photo-chemical hydroxylation of surface defects. This phenomenon was further investigated with regard to its influence on the electronic structure of the indium tin oxide (ITO)/TiO2 interface found in dye-sensitized solar cells. The experiments suggest that UV radiation can cause a small but significant change of the charge injection barriers at the interface. The determined band line-ups revealed electron injection barriers of ~0.3-0.5 eV, while UV radiation caused an increase of about 0.15 eV. This might have the potential to further impede electron transfer to the ITO electrode and affect the performance of solar cell device. Another type of photovoltaic cell using nanocrystalline material is a heterojunction bulk solar cell. Conversion efficiencies of such devices are currently only about 3% due to the inefficient charge separation at interfaces formed by blending organic and inorganic material. An approach to improve efficiencies in such devices is the use of covalently bonded conductive polymer/inorganic hybrid nanocrystals. In this study a prototypical model system was investigated with PES with the aim to develop a measurement protocol that allows the determination of electronic properties for such hybrid materials. The comparison of the relative core-level binding energies of the organics-functionalized CdSe nanocrystal compared to the ligand-free CdSe nanocrystal and the arylselenophosphate ligand material enabled the determination of the electronic structure at the interface. Core-level measurements support the hypothesis that the Se functionality of the organic ligand coordinates to the Cd sites on the nanopthesis surface.
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Schumm, Benjamin. "Herstellung und Charakterisierung periodisch strukturierter Dünnschichten für den Einsatz in optoelektronischen Bauteilen." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-119851.
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Transparente Elektroden finden breite Verwendung in unterschiedlichen kommerziellen Produkten. Dünnschichtsolarzellen basieren ebenso auf diesen Funktionsschichten wie Displays oder organische Leuchtdioden. Im Falle von Dünnschichtsolarzellen kann durch gezielte Einstellung der Oberflächentextur der transparenten Elektrode ein entscheidender Einfluss auf die erreichbare Effizienz genommen werden. Dabei wird eine Verlängerung der Weglänge des Lichtes im Absorbermaterial durch Mehrfachreflexionen angestrebt. Häufig werden dafür Schichten transparenter leitfähiger Oxide (TCO) gezielt texturiert. Eine weitere Möglichkeit zur Erzeugung transparenter Elektroden stellt die Verwendung feiner Metallgitter dar. Diese ermöglichen hohe Leitfähigkeiten im Bereich der Gitterstege und hohe Transparenz im Bereich zwischen den Stegen.
In dieser Arbeit sollte ein auf nasschemischen Prozessen basierendes Verfahren entwickelt werden, mit dem es möglich ist, sowohl strukturierte TCO-Elektroden als auch Metallgitter unterschiedlicher Geometrien gezielt herzustellen. Die Leistungsfähigkeit der Elektroden sollte anhand der Integration in entsprechende Bauteile bewertet werden. Namentlich sollte dieser Prozess für Cd2SnO4 (engl. Cadmium Tin Oxide, CTO) als ein TCO-Material hoher Transparenz und Leitfähigkeit sowie für Silber und Kupfer als metallische Systeme anwendbar sein. Als zielführende Methode kam die Nanoprägelithographie (von engl. Nanoimprint Lithography, NIL) zum Einsatz. Dieses Verfahren erlaubt die schnelle, einfache und kostengünstige Herstellung strukturierter Oberflächen. Grundsätzlich wird dazu ein strukturierter Elastomerstempel in eine Schicht eines zu vernetzenden Materials gepresst. Während des Pressens findet die Vernetzung statt. Nach anschließender Separation von Stempel und Schicht resultiert eine strukturierte Oberfläche. Gängige Präkursorensysteme für anorganische Verbindungen, bei denen Vernetzungsprozesse ablaufen, stellen Sol-Gel-Methoden und sogenannte polymere Präkursoren dar. Für letztere werden Metallzitrate mit Ethylenglykol verestert, um ein vernetztes Polymer zu generieren. Nach thermischem Entfernen der Organik bleibt das Metalloxid zurück.
Im Rahmen dieser Arbeit ist ein Präkursorensystem entwickelt worden, das Metallionen komplexiert, auf Glassubstrate beschichtet werden kann und eine thermische Polymerisation erlaubt. Aus dem erhaltenen polymeren Präkursor konnten die Zielverbindungen durch thermisches Zersetzen einerseits in Pulverform und andererseits über vorhergehende Schleuderbeschichtung in Form dünner Schichten erhalten werden. Im Falle des kubischen Cd2SnO4 wurde im Rahmen dieser Arbeit erstmals eine Nanopulver-Synthese mit phasenreinem Produkt aus flüssigem Präkursor beschrieben. Dafür stellten sich der Anteil der verwendeten organischen Bestandteile sowie die Zersetzungsgeschwindigkeit als entscheidende Einflussparameter heraus. Zudem wurden CTO Dünnschichten mit dem beschriebene Präkursor hergestellt. Eine optimale Brenntemperatur zur Erzeugung phasenreiner CTO-Schichten von 700 wurde ermittelt. Die Zersetzungsgeschwindigkeit (bzw. Aufheizrate) beeinflusste die Oberflächenmorphologie der erhaltenen Schichten maßgeblich. Eine schrittweise Zersetzung (100 °C, 200 °C, Zieltemperatur) führte dabei in effizienter Weise zu kompakten Schichten. Diese zeigten sehr gute optische und elektronische Eigenschaften. So konnten etwa 300 nm dicke CTO-Schichten mit spezifischen Widerständen von ca. 1 • 10^(−5) Ohm m bei einer Transmission von etwa 80 % (inklusive Glassubstrat) erhalten werden. Derartige CTO-Schichten konnten erfolgreich als transparente Frontelektroden für a-Si Dünnschichtsolarzellen verwendet werden. Ein positiver Einfluss periodischer Linienstrukturen auf die Lichteinfangeigenschaften und den resultierenden Photostrom im Vergleich zu flachen CTO-Schichten wurde bestätigt.
Auch für die Herstellung von CdTe-Dünnschichtsolarzellen konnten die CTO-Schichten erfolgreich eingesetzt werden. Die erreichten Effizienzen lagen jedoch lediglich im Bereich von 3 bis 3,6 %. Ein signifikanter Unterschied zwischen flachen und strukturierten Proben konnte nicht ausgemacht werden. Durch die reduzierenden Eigenschaften von Zitronensäure und Ethylenglykol gegenüber Ag+ und Cu2+ Ionen war es möglich, die Metalle in elementarer Form durch einfache thermische Behandlung des Präkursors zu erhalten. Während dieser Prozess für silberhaltige Systeme relativ einfach zu realisieren war, musste bei kupferhaltigen Proben die Bildung oxidischer Nebenphasen festgestellt werden. So war für Letzteres eine reduktive Nachbehandlung vollständig oxidierter Proben im Wasserstoffplasma zielführend und lieferte leitfähige Dünnschichten mit hohem Cu(0)-Anteil. Im Falle von Silber führte eine geeignete thermische Behandlung der Präkursorschicht zu dünnen, leitfähigen Silberschichten mit spezifischen Widerständen von ca. 6 • 10^(−8) Ohm m (Festkörper: ca.1 • 10^(−8) Ohm m). Die Übertragung des NIL-Prozesses gelang sowohl für silber- als auch kupferhaltige Systeme. Mit NIL-strukturierten Silberdünnschichten gelang so die Herstellung semitransparenter Elektroden mit spezifischen Widerständen von 2,2 • 10^(−7) Ohm m, welche in Elektrolumineszenzbauteilen verwendet wurden. Aufgrund der relativ niedrigen Temperaturen, die für die Zersetzung des Silberpräkursors nötig waren (ca. 250 ), war die Fertigung entsprechender Elektroden und Bauteile auch auf Polyimidfolien möglich.
Insgesamt bleibt die Erkenntnis, dass NIL-strukturierte dünne Schichten erfolgreich in optoelektronische Bauteile integriert werden konnten. Variable Präkursorsysteme erlauben die Herstellung verschiedener Schichten und somit Anwendungen in unterschiedlichen Bauteilen. Polymere Präkursoren haben sich als geeignet für dieses Vorgehen erwiesen und können relativ einfach auf diverse oxidische Stoffsysteme übertragen werden. Gleichzeitig eignen sie sich zur Herstellung metallischer transparenter Elektroden durch NIL-Strukturierung, was insbesondere im Hinblick auf flexible Bauteile von Vorteil ist.
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ORTIZ, MIRANDA ANNETTE. "Development of analytical methods for the characterization of tempera paintings at micro- and nano-scale and their deterioration and biodeterioration processes." Doctoral thesis, Universitat Politècnica de València, 2017. http://hdl.handle.net/10251/90571.
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Egg (the whole, the yolk or the white) is a natural product used since ancient times as tempera painting medium mainly in Europe and the Mediterranean Basin countries. In addition, egg is a complex multicomponent microstructured system susceptible of being influenced by the pigments that compose the paints, as well as a source of nutrient susceptible of biodeterioration. Modifying effect of artists' pigments on the binding medium as well as, the microbial biodeterioration are responsible for changes in the structure and composition of the binding medium and, consequently, on the physico-chemical properties of the paint.
For this purpose, analytical techniques such as Fourier transform infrared spectroscopy - attenuated total reflection (FTIR-ATR) was used for the chemical characterization, Field emission scanning microscopy (FESEM) and Atomic force microscopy - nanoindentation (AFM-nanoindentation) were run for morphological and mechanical characterization of the deterioration processes resulted from the pigment-binder interactions involved in tempera painting.
On the other hand, the current research report the application of the voltammetry of microparticles (VMP), complemented with FTIR-ATR, FESEM and AFM-nanoindentation techniques to monitor the deterioration of a series of tempera reconstructed model paint specimens under the action of different biological agents. This methodology would be of application for identifying the type of biological agent causing deterioration of painting, which is an important problem affecting cultural heritage. The analysis of biodeterioration processes is complicated by the fact that the action of microorganisms can affect both pigment and binding media. The deterioration of pictorial specimens by Acremonium chrysogenum, Aspergillus niger, Mucor rouxii, Penicillium chrysogenum and Trichoderma pseudokoningii fungi and Arthrobacter oxydans, Bacillus amyloliquefaciens and Streptomyces cellulofans bacteria was tested using sample-modified graphite electrodes immersed into aqueous electrolytes.
Finally, the study carried out by means of FTIR-ATR, FESEM and AFM-nanoindentation confirms that egg proteins attached to the pigment grains changes their secondary structures. The results obtained also confirm that proteins and phospholipids are prevalently established linkages with the solid particles of pigment whereas triglycerides should be integrated in the complex binding network responsible for the cohesion of the paint film. Interactions between egg components with solid pigment particles are described and correlated with micromorphology and mechanical properties determined at micro- and nano-scale on the reconstructed model paint specimens. As a result of the crossing of VMP data with the results obtained by means of FTIR, FESEM and AFM-nanoindentation, the voltammetric signals obtained were associated to the electrochemical reduction of pigments and different complexes associated to the binding media. These results were particularly relevant in the study of biodeterioration, to allowing the electrochemical monitoring of biological attack.El huevo (entero, yema o clara) es un producto natural utilizado desde la antigüedad como medio aglutinante en la pintura al temple, principalmente en Europa y los países de la cuenca mediterránea. Además, el huevo es un complejo sistema multicomponente microestructurado susceptible de ser alterado por los pigmentos que componen las pinturas, así como fuente de nutrientes susceptible de biodeterioro. El efecto de los pigmentos sobre el medio aglutinante, así como el biodeterioro microbiano son responsables de cambios en la estructura y composición del medio aglutinante y, por consiguiente, en las propiedades fisicoquímicas de la pintura. Es por esto que, se utilizaron técnicas analíticas como la Espectroscopía Infrarroja por Transformada de Fourier en modo Reflexión Total Atenuada (FTIR-ATR), para la caracterización química de los procesos de deterioro resultantes de las interacciones pigmento-aglutinante en la pintura al temple. Así mismo, se utilizó Microscopía Electrónica de Emisión de Barrido (FESEM) para el estudio morfológico de las muestras, y para el estudio de las propiedades mecánicas Microscopía de Fuerza Atómica en modo Nanoindentación (AFM-nanoindentación). Por otro lado, la presente investigación propone el uso de la Voltamperometría de Micropartículas (VMP), en conjunto con otras técnicas de análisis como FTIR-ATR, FESEM y AFM-nanoindentación para el estudio del biodeterioro producido por hongos y bacterias sobre una serie muestras pictóricas sometidas. El estudio de las alteraciones causadas por el biodeterioro es complicado por el hecho de que la acción de los microorganismos puede afectar tanto al pigmento como al medio aglutinante. Para esto, se prepararon una serie de muestras de pinturas al temple y emulsión que fueron inoculadas con los hongos Acremonium chrysogenum, Aspergillus niger, Mucor rouxii, Penicillium chrysogenum, y Trichoderma pseudokoningii, y las bacterias Arthrobacter oxydans, Bacillus amyloliquefaciens y Streptomyces cellulofans. El estudio voltamperometrico se realizó utilizando electrodos de grafito modificados con las muestras inmersos en un electrolito acuoso. Las conclusiones obtenidas de manera general, apuntan a que las proteínas presentes en el huevo cambian su estructura secundaria al adherirse a los granos de pigmento. La información química, morfológica y mecánica obtenida por las diferentes técnicas de análisis instrumental es consistente. Finalmente, como resultado del cruce de los datos VMP con los resultados obtenidos mediante FTIR, FESEM y AFM-nanoindentación, las señales voltamperometricas obtenidas se asociaron a la reducción electroquímica de los pigmentos y a los complejos formados con el medio aglutinante. Estos resultados fueron particularmente relevantes en el estudio del biodeterioro de las películas pictóricas inoculadas, para permitir la monitorización electroquímica del ataque microbiológico.
L'ou (sencer, rovell o clara) és un producte natural utilitzat des de l'antiguitat com a mitjà aglutinant en la pintura al tremp, principalment a Europa i els països de la conca mediterrània. A més, l'ou és un complex sistema multicomponent MICROESTRUCTURAT susceptible de ser alterat pels pigments que componen les pintures, així com a font de nutrients susceptible de biodeterioració. L'efecte dels pigments sobre el medi aglutinant, així com el BIODETERIORI microbià són responsables de canvis en l'estructura i composició del medi aglutinant i, per tant, en les propietats fisicoquímiques de la pintura. És per això que, es van utilitzar tècniques analítiques com l'Espectroscòpia Infraroja per Transformada de Fourier en mode Reflexió Total Atenuada (FTIR-ATR), per a la caracterització química dels processos de deteriorament resultants de les interaccions pigment-aglutinant en la pintura al tremp. Així mateix, es va utilitzar Microscòpia Electrònica d'emissió de Rastreig (FESEM) per a l'estudi morfològic de les mostres, i per a l'estudi de les propietats mecàniques Microscòpia de Força Atòmica en mode Nanoindentació (AFM-nanoindentació). D'altra banda, la present investigació proposa l'ús de la Voltamperometría de Micropartícules (VMP), en conjunt amb altres tècniques d'anàlisi, com FTIR-ATR, FESEM i AFM-nanoindentació per a l'estudi de l'biodeterioració produït per fongs i bacteris sobre una sèrie de mostres pictòriques sotmeses. L'estudi de les alteracions causades pel biodeteriori és complicat pel fet que l'acció dels microorganismes pot afectar tant el pigment com al medi aglutinant. Per això, es van preparar una sèrie de mostres de pintures al tremp i emulsió que van ser inoculades amb els fongs Acremonium chrysogenum, Aspergillus niger, Mucor rouxii, Penicillium chrysogenum, i Trichoderma pseudokoningii i els bacteris Arthrobacter oxydans, Bacillus amyloliquefaciens i Streptomyces cellulofans. L'estudi voltamperomètric es va realitzar utilitzant electrodes de grafit modificats amb les mostres immersos en un electròlit aquós. Les conclusions obtingudes de manera general, apunten que les proteïnes presents en l'ou canvien la seva estructura secundària al adherir-se als grans de pigment. La informació química, morfològica i mecànica obtinguda per les diferents tècniques d'anàlisi instrumental és consistent. Finalment, com a resultat de l'encreuament de les dades VMP amb els resultats obtinguts mitjançant FTIR, FESEM i AFM-nanoindentació, els senyals voltamperomètrics obtinguts es van associar a la reducció electroquímica dels pigments i als complexos formats amb el medi aglutinant. Aquests resultats van ser particularment rellevants en l'estudi del biodeteriori de les pel·lícules pictòriques inoculades, per tal de permetre la monitorització electroquímica de l'atac microbiològic.
Ortiz Miranda, A. (2017). Development of analytical methods for the characterization of tempera paintings at micro- and nano-scale and their deterioration and biodeterioration processes [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/90571
TESIS
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Lambert, Darcy Erin. "Nanostructured Extremely Thin Absorber (ETA) Hybrid Solar Cell Fabrication, Optimization, and Characterization." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/637.
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Traditional sources of electrical energy are finite and can produce significant pollution. Solar cells produce clean energy from incident sunlight, and will be an important part of our energy future. A new nanostructured extremely thin absorber solar cell with 0.98% power conversion efficiency and maximum external quantum efficiency of 61% at 650 nm has been fabricated and characterized. This solar cell is composed of a fluorine-doped tin oxide base layer, n-type aluminum doped zinc oxide nanowires, a cadmium selenide absorber layer, poly(3-hexylthiophene) as a p-type layer, and thermally evaporated gold as a back contact. Zinc oxide nanowire electrodeposition has been investigated for different electrical environments, and the role of a zinc oxide thin film layer has been established. Cadmium selenide nanoparticles have been produced and optimized in-house and compared to commercially produced nanoparticles. Argon plasma cleaning has been investigated as a method to improve electronic behavior at cadmium selenide interfaces. The thermal anneal process for cadmium selenide nanoparticles has been studied, and a laser anneal process has been investigated. It has been found that the most efficient solar cells in this study are produced with a zinc oxide thin film, zinc oxide nanowires grown under constant -1V bias between the substrate material and the anode, cadmium selenide nanoparticles purchased commercially and annealed for 24 hours in the presence of cadmium chloride, and high molecular weight poly(3-hexylthiophene) spin-coated in a nitrogen environment.
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Dou, Yusheng. "The electronic structure of cadmium oxides studied by photoemission spectroscopy." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.389218.
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Oehlstrom, Karsten. "Präparation und Charakterisierung von Cadmium-Stannat als alternatives transparentes leitfähiges Oxid." [S.l. : s.n.], 2002. http://deposit.ddb.de/cgi-bin/dokserv?idn=96797948X.
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PEREIRA, LUCIANO F. D. "Estudo do gradiente de campo elétrico e da estrutura eletrônica do ZnO dopado com Co e Cd e do HfOsub(2) dopado com Ta por cálculos de primeiros princípios." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10031.
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Tese (Doutoramento)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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Türker, Muhammed [Verfasser], and Thomas [Akademischer Betreuer] Wichert. "Analyse zur Bildung atomarer Defektkomplexe nach Dotierung von Cadmium-Tellurid und Zink-Oxid / Muhammed Türker. Betreuer: Thomas Wichert." Saarbrücken : Saarländische Universitäts- und Landesbibliothek, 2012. http://d-nb.info/1052551270/34.
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Svozilová, Eva. "Stanovení obsahu kadmia v rostlinném pletivu smrku ztepilého a buku lesního po aplikaci nanočástic oxidu kademnatého." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-295648.
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The aim of this thesis is to monitor cadmium content in needles of Norway spruce and European beech leaves after controlled exposure to cadmium oxide nanoparticles and evaluate the potential risks of such nanoparticles to plants. Needles and leaves were harvested after a one-week and two-week exposure and prior to analysis of cadmium content, they were modified using relevant procedures. Samples were mineralized in nitric acid using pressurized microwave mineralizer and subsequently analyzed by atomic absorption spectrometry (AAS) with electrothermal atomization of cadmium content. Based on the results AAS analysis the transport of nanoparticles into the plant tissue of studied species was evaluated, comparing the content of cadmium in one week and two weeks experiment in the washed and unwashed samples of needles and leaves.
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FRANZIN, ROBERTA N. A. "Interacoes hiperfinas no sitio do 111supCd em oxidos delafossite ABOsub2 (A=Ag, Cu; B=Al, Cr, Fe, In, Nd e Y)." reponame:Repositório Institucional do IPEN, 1996. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10467.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:92/02990-0
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Abdelkader, Zebda. "Propriétés microstructurales et électriques d'électrodes d'oxydes SnO2 et Cdln2O4 : application à la détection électrochimique directe de l'hybridation de l'ADN." Grenoble INPG, 2007. http://www.theses.fr/2007INPG0024.
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Deux types d'oxydes métalliques transparents conducteurs - SnO2 et Cdln2O4 - ont été déposés en couches minces par la technique de pyrolyse d'aérosol et ont été utilisés comme électrodes semi-conductrices en vue de la détection électrochimique directe de l'hybridation de l'ADN (c'est à dire sans utilisation de marqueurs ). Les conditions de dépôt ont été modifiées de façon à obtenir des couches avec différentes caractéristiques. Les corrélations entre les propriétés microstructurales et électriques des électrodes ainsi réalisées et leur sensibilité électrochimique à l'hybridation de l'ADN ont été particulièrement étudiées. Le résultat majeur de cette étude réside dans le fait que la sensibilité à l'hybridation de l'ADN des électrodes d'oxydes semi-conducteurs étudiés est liée essentiellement à la résistivité électrique de ces électrodes. Cela se vérifie en particulier dans le cas des couches de Cdln2O4 pour lesquelles la microstructure a peu évolué. En revanche, dans le cas des couches de SnO2, la microstructure des couches est un paramètre qui intervient d'une manière importante au même titre que la résistivité électriqueTwo kinds of metallic transparent and conductive oxides - SnO2 and CdIn2O4 - have been deposited in thin films using the aerosol pyrolysis technique. They have been used as semi-conductor electrodes in view of the label-free electrochemical detection of DNA hybridization. The deposition conditions have been modified in order to obtain films exhibiting different characteristic. The correlations between micro structural and electrical properties of the as-deposited electrodes and their sensitivity to DNA hybridization have been particularly studied. The major result shows that the sensitivity to DNA hybridization of the studied semi-conductor electrodes is linked to the electrical resistivity of the electrodes. This is particularly true in the case of Cdln2O4 films, the microstructure of which exhibiting nearly no evolution. Ln contrast, in the case of the SnO2 films, the microstructure is an important parameter as well as the electrical resistivity
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Pecaut, Jacques. "Ingénierie cristalline de matériaux organo-minéraux pour l'optique non linéaire quadratique." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0037.
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Des chromophores non lineaires, derives de la pyridine, sont ancres dans des matrices minerales par un reseau de liaisons hydrogene courtes. Les sels remarquables que nous avons isole sont les dihydrogenoarseniate, chlorure et bromure de 2-amino-5-nitropyridinium dont les signaux de second harmonique sont equivalents ou superieurs a ceux du 3-methyl-4-nitropyridine-n-oxyde (pom). Les composes d'addition, chlorure de cadmium de la bis (4-nitropyridine-n-oxyde) et le bis (bromure mercurique) de la 4-nitropyridine-n-oxyde possedent des structures polaires dont la cohesion de l'entite non lineaire est assuree a la fois par la liaison metal-oxygene et la liaison hydrogene. Leur reponse en generation de second harmonique est equivalente ou superieure a celle du ktiopo#4 (ktp). Des composes possedant un reseau cationique pseudo-centrosymetrique de dimethylaminopyridinium, de guanidinium (cation octupolaire de symetrie d#3#h) et de dimethylammonium-stibazolium-n-hydroxyde sont decrits dans la troisieme partie de ce travail. Cette ingenierie est une voie d'acces a des cristaux non lineaires mecaniquement et chimiquement stables. Il s'avere que le nombre important de sites donneurs et accepteurs d'hydrogene de la matrice dans laquelle est integree la molecule organique est preponderant dans l'obtention de structures non centrosymetriques. Ces matrices se presentent alors generalement sous la forme de chaines ou de couches a caractere polymere
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Asthana, Abhishek. "Modélisation mathématique de la formation des NOx et de la volatilisation des métaux lourds lors de l'incinération sur grille d'ordures ménagères." Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL018N/document.
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Dans une optique de maîtrise du procédé d’incinération des ordures ménagères et de ses possibles émissions polluantes, nous avons développé un modèle mathématique qui simule un lit d’ordures ménagères en combustion sur une grille mobile. Ce modèle décrit la plupart des phénomènes physicochimiques et thermiques intervenant lors de l’incinération : séchage et pyrolyse de la charge, combustion et gazéification du carbone résiduel, transferts thermiques, effondrement du lit, brassage… Il intègre également une description des mécanismes de volatilisation des métaux lourds et de formation des NOx. La cinétique de départ des métaux lourds est modélisée en tenant compte des différentes étapes de transport (transfert externe, diffusion intraparticulaire, volatilisation) au moyen de l’approche des temps caractéristiques additifs. Dans le cas simulé du cadmium, la prédiction d’une volatilisation quasi-complète est conforme aux résultats de la littérature. Le sous-modèle NOx prend en compte les mécanismes de formation thermique, prompt, combustible, par l’intermédiaire de N2O, ainsi que les mécanismes de réduction homogène par recombustion et hétérogène par le carbone résiduel. Les calculs révèlent que prédominent la formation par le mécanisme combustible et la destruction par la réduction hétérogène. Enfin, le modèle de lit a été utilisé pour étudier l’influence des divers paramètres opératoires : température, débit et distribution d’air primaire, taille des particules de déchets, brassage et schéma de brassage. Les résultats sont présentés et discutés en détail. L’influence des conditions opératoires sur l’efficacité du procédé et sur les émissions de Cd et NOx est analyséeAs a tool for controlling the Municipal Solid Waste (MSW) incineration process and its possible pollutant emissions, a mathematical model of the MSW bed burning on travelling grate of an incinerator was developed. The model describes most of the physico-chemical and thermal phenomena taking place in incineration like the drying and pyrolysis of the feed, combustion and gasification of char, oxidation of pyrolysis gases, heat transfer, bed shrinking, feed stirring, etc. Also described in the model are the mechanisms of Heavy Metals (HM) volatilization and NOx formation. Kinetics of HM release was modelled using the approach of additive reaction times accounting for the various transport mechanisms involved: external transfer, intra-particle diffusion and actual volatilization. In the case simulated, i.e. of Cd, almost total volatilization is predicted, which is confirmed by literature findings. The NOx sub-model takes into account most of the common mechanisms of formation like thermal, prompt, fuel, N2O intermediate and also NOx reduction by homogeneous reburning and heterogeneous reduction by char. Calculations show that NOx formation is predominated by the fuel mechanism and destruction by the heterogeneous reduction. Finally, the bed model was applied to study the influence of various operating parameters like flow rate, temperature and distribution of air under grates, waste particle size, feed stirring and the stirring scheme. The results are presented and discussed in detail and the influence of operating conditions on process efficiency and on emissions of Cd and NOx is analyzed
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CAVALCANTE, FABIO H. de M. "Estudo de interacoes hiperfinas em oxidos RCoOsub(3) (R=Gd e Tb) e filmes finos de HfOsub(2) por meio da tecnica de espectroscopia de correlacao angular gama-gama perturbada." reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9422.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
26
Ha-Thi, Minh-Huong. "Nouvelles architectures supramoléculaires à base de ligands phosphorés fluorescents : synthèse, études photophysiques et applications." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2007. http://tel.archives-ouvertes.fr/tel-00254039.
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Ce travail concerne l'ingénierie de nouveaux systèmes supramoléculaires à base de ligands phosphorés fluorescents en vue de la réalisation des nouveaux matériaux optiques et de la détection de métaux lourds. Deux nouvelles séries de chromophores de type donneur-accepteur contenant des motifs phénylacétylène et une fonction oxyde ou sulfure de phosphine ont été synthétisées en utilisant le couplage de Sonogashira comme étape clé. Elles possèdent des rendements quantiques de fluorescence élevés ainsi qu'un transfert de charge efficace à l'état excité. Les oxydes de phosphine fluorescents présentent également des propriétés intéressantes en absorption à deux photons et en optique non linéaire. Nous avons également synthétisé des nouveaux ligands bidentes de type oxyde ou sulfure de phosphine pour la détection de métaux lourds polluants. Les chélates d'oxydes de phosphine complexent efficacement le plomb et le cadmium dans un mélange CH3CN/CHCl3. Ils offrent également la possibilité de la détection par fluorescence par absorption à deux photons. Les chélates de sulfures de phosphine présentent de très bonne sensibilité et sélectivité pour le mercure dans un milieu partiellement aqueux. D'autre part, les chélates d'oxydes de phosphine permettent une bonne sensibilisation des ions lanthanides par un transfert d'énergie du ligand vers le métal complexé. Une étude complète du transfert d'énergie de l'un des ligands vers l'ion europium a été réalisée.
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Saifi, Ali. "Contribution à l'étude des propriétés magnétiques des systèmes spinelles isolants CdCr2xIn2-2xS4 et ZnCr2xGa2-2xO4 : phases type verre de spin." Paris 6, 1986. http://www.theses.fr/1986PA066519.
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Ces systèmes présentent la percolation et la frustration. Le premier composé est ferromagnétique, tandis que le second présente des interactions antiferromagnétiques. On étudie en fonction de x les transitions de ces composés. Les transitions de phase du gallate ont été étudiées par effet Mössbauer. On a mis en évidence que pour x0,75 l'ordre magnétique tend vers un ordre caractéristique de la "vraie" phase verre de spin.
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Benjelloun, Nadia. "Caracterisation des niveaux profonds dans le materiau photorefractif bi : :(12) geo::(20) par analyse de transitoires de courant photo-induit." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13183.
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La methode est utilisee pour l'etude de la densite d'etats dans la bande interdite du silicium amorphe hydrogene et sur cdin::(2)s::(4). La caracterisation des niveaux ayant des energies d'ionisation thermique entre 0,1 ev et 0,9 ev, le modele de transfert de charge decrivant l'effet photorefractif et l'evaluation du niveau de recombinaison, sont faits dans le materiau photorefractif. Les effets du dopage (fer) et du codopage (fer, vanadium) sur les niveaux sont consideres. Le centre responsable de la capture d'electrons est aussi etudie par absorption optique et photoconductivite photoinduites. Les resultats s'accordent avec ceux des mesures de photorefractivite
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Kuo, Tz-Jun, and 郭子駿. "Synthesis of Zinc Oxide and Cadmium Oxide Nanowires." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/npjx85.
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葉佳佳, Jia-Jia Ye, and 葉佳佳. "Effect of nitric oxide on the cadmium toxicity in rice seedling roots." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/67970819608840954584.
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碩士國立中興大學
農藝學系所
100
In this thesis, rice (Oryza sativa L., cv. Taichung Native 1, TN1) seedlings were used to investigate the effect of nitric oxide (NO) on the toxicity of roots caused by cadmium. Cadmium treatment significantly inhibited plant height, root length, fresh weight and dry weight, as well as cadmium content in cadmium-treated shoots and roots increased with prolonged duration of incubation. In plants, NO is involved in many physiological responses, such as defense response to biotic and abiotic stress. In this study, 10μM SNP (NO donor) pretreatment significantly recovers cadmium inhibited root length, fresh weight and dry weight of rice root, and decrease oxidative stress induced by cadmium. It is clearly that NO decreased malonaldehyde and hydrogen peroxide content of rice roots induced by cadmium. SNP-treated roots decreased with SOD and POD activity, but increased with CAT activity. However, SNP pretreatment is not decreased in cadmium content, it is increasing. It is demonstrate that SNP-pretreated caused antioxidative enzymes activity decrease in cadmium toxicity and recover rice seedlings growth, as well as not uptake cadmium content.
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Aldemir, Müge [Verfasser]. "Metal oxide supported cadmium sulfide for photocatalytic synthesis of homoallylamines / vorgelegt von Müge Aldemir." 2006. http://d-nb.info/978677617/34.
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Schleife, André [Verfasser]. "Exciting imperfection : real-structure effects in magnesium-, cadmium-, and zinc-oxide / von André Schleife." 2010. http://d-nb.info/1012878783/34.
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Zacate, Matthew O. "A microscopic study of the interaction between aliovalent dopants and native defects in group IV oxides : indium and cadmium in ceria and zirconia." Thesis, 1997. http://hdl.handle.net/1957/34309.
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In order to understand better the defect structure and dynamics associated
with lower valent dopants complexed with native defects in group IV oxides, In/Cd
perturbed angular correlation spectroscopy was performed in ceria and zirconia. Examining
the orientation symmetry axis of defects in ceria single crystals at low temperature
has allowed the identification of a cadmium with a bound near-neighbor
oxygen-vacancy complex as well as a complex involving a cadmium with two opposing,
near-neighbor oxygen vacancies. The orientation of the symmetry axis of a third
complex is reported; however, this information is not sufficient to identify it. Complementing
these low temperature studies, the dynamics of the cadmium/oxygen-vacancy
interaction in zirconia at high temperatures was studied. The motion of the oxygen
vacancy at high temperatures results in a damping of the PAC signal. This damping
is not well characterized by the heuristic Marshall-Meares PAC fitting function, and
a model is proposed to fit the data in terms of three physical parameters associated
with the vacancy's motion. These parameters are the rate at which a bound oxygen
vacancy hops among equivalent sites about the probe, the rate at which a bound
vacancy detraps, and the rate at which a vacancy is trapped by cadmium. Fits of
individual spectra using this model give respective activation energies of 0.3-0.6 eV,
0.9-1.6 eV, and 0.4-0.6 eV. The uncertainty in these energies can most likely be
reduced by fitting spectra from multiple temperatures simultaneously. Despite the
large uncertainty in the fitted energies, the values are physically reasonable and indicate
that the model adequately describes the motion of the oxygen vacancy about
cadmium.Graduation date: 1997
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鄭匡博. "Effect of nitric oxide on cadmium-induced cytotoxicity and p38 kinase activation in lung cancer cells." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/71106467930983085169.
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Martin, Vincent. "Composition and Structure Dependence of the Photoelastic Response of Oxide Glass." 2011. http://hdl.handle.net/10222/14083.
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The isotropy of a glass can be broken by the application of a mechanical stress giving rise to a phenomenon of birefringence. Some lead-containing glass compositions are known to prevent this phenomenon and they are called zero-stress optic glass. Mueller’s theory of photoelasticity attempts to explain the structural origin of the photoelastic response in glass and crystal. Zwanziger’s empirical model is able to predict the photoelastic response of a glass based on its composition and the crystal structure of its constituents. Lead-, tin-, antimony-, zinc-, and cadmium-containing glasses were investigated in the binary silicate, borate, and phosphate systems. The stress optic coe?cient of these binary glasses was measured experimentally using the S´enarmont method or
found in the literature. Solid-state Nuclear Magnetic Resonance spectroscopy and M¨ossbauer spectroscopy were mainly used to investigate the local environment of the cations. The photoelastic response of a glass and its structure were correlated, and
the results were compared with the expectations arising from Mueller’s theory and Zwanziger’s empirical model. The theory and the model were both tested and their reliability was discussed. Zero-stress optic glasses are of technological interest, but new environmental regulations forbids the use of lead in materials, including glass. From experimental results and literature, a global strategy to design new zero-stress optic glasses was established. New lead-free zero-stress optic glasses were discovered with properties similar to the lead-containing zero-stress optic glass (high index of refraction, transparency, no coloration). The study of the structural dependence of the photoelastic response of oxide glass contributed to identify new parameters in?uencing the photoelasticity, such as covalency, polarizability and natural deformation of the additive.
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Kepler, Keith Douglas. "Photoluminescence and conductance as probes of the adduct-induced modulation of Cadmium Sulfide and Cadmium Selenide depletion widths II. Mercury-assisted synthesis of intermetallic and metal oxide materials /." 1996. http://catalog.hathitrust.org/api/volumes/oclc/36221817.html.
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Thesis (Ph. D.)--University of Wisconsin--Madison, 1996.Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 204-206).
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Jagtap, Amardeep M. "Investigations on Photophysical Properties of Semiconductor Quantum Dots (CdxHg1-xTe,Ag2S) and their Interactions with Graphene Oxide, Organic Polymer Composites." Thesis, 2016. http://hdl.handle.net/2005/3069.
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The motivation of this thesis is to understand the physical properties of semiconductor quantum dots (QDs) and to get insight on the basic physics of charge separation in composites made from QDs with graphene oxide (GO)/organic semiconductors. The flexion phonon interactions is one of fundamental issues in solid state physics, which has a significant effect on both electrical and optical properties of solid state materials. This thesis investigates the physical properties of aqueous grown QDs through exciton-phonon coupling and non-radiative relaxation of excited carriers which have been carried out by temperature dependent photoluminescence spectroscopy. Several e orts have been made in order to understand the basic physics of photo induced
charge separation in the hybrid systems made from QDs with graphene oxide and organic semiconductors. Investigations on the photoconductivity of the devices made from these hybrid composites have been carried out keeping the motive of its application in nanotechnology. This thesis work is presented in six chapters inclusive of summary and directions for future work.
Chapter 1 discusses the background knowledge and information of the general properties of semiconductor nanostructures, QDs and their hybrid nanocomposites. Chapter 2 deals with the sample preparation and experimental techniques used in this thesis. Chapter 3 elaborates the exciton-phonon scattering and nonradiative relaxations of excited carriers in visible emitting cadmium telluride QDs with help of temperature and size dependent photoluminescence. Chapter 4 presents the investigations on time resolved photoluminescence dynamics and temperature dependent photoluminescence properties of near infrared (NIR) emitting mercury
cadmium telluride (CdHgTe). Chapter 5 discusses the importance of NIR emitting silver sulphide (Ag2S) QDs and gives insight of nonradiative recombinations through defect/trap states. Chapter 6 investigates the excited state interactions between CdHgTe QDs and GO. Chapter 7 focuses on the understanding of basic
physics of charge separation/transfer between poly (3hexylthiophene) and Ag2S QDs.
Chapter 1: Semiconductor nanostructures have attracted significant scientific attention due to their fundamental physical properties and technological interests. Quasi zero dimensional nanocrystals or quantum dots (QDs) have shown unique optical and electrical properties compared to its bulk counterpart. These QDs show discrete energy levels due to the quantum confinement effect hence known as arti cial atoms. Large surface to volume ratio in these QDs is expected to play a crucial role in determing the photo-physical properties. Temperature dependent photoluminescence is a powerful tool for understanding the role of the large surface area on exciton recombination process in QDs. Inorganic QDs combined with different materials like graphene oxide or organic semiconductors forms an exciting class of synthetic materials which integrates the properties of organic and inorganic semiconductors. It is quite important to understand the basic physics of electronic interactions in these composites for its future application in many elds.
Chapter 2: Synthesis of the inorganic QDs, graphene oxide, composites and fabrication of devices is an important and integral part of this thesis. Hydrothermal and three necked ask technique is adopted to get highly dispersible colloidal
quantum dots in solvents. Synthesis of graphene oxide from graphite through oxidation and ultrasonication has been carried out to obtain homogenous dispersed graphene oxide in water. Structural properties have been studied by techniques like X ray diffraction, Raman spectroscopy, X ray photoelectron spectroscopy
and high resolution transmission electron microscopy. Morphological properties are studied by atomic force microscopy and transmission electron microscopy. Optical properties are investigated by absorption spectroscopy, steady state and time resolved photoluminescence spectroscopy. Photoconductivity characteristics are analyzed to understand the basics of enhanced current in the various devices made from QDs composites.
Chapter 3:Investigations on exciton phonon coupling and nonradiative relaxations in various sizes of visible light emitting cadmium telluride (CdTe) QDs size have been presented. Due to the large surface area, QDs are prone to have defect/trap states which can affect the exciton relaxation. Hence, understanding the role of such defect/trap states on photoluminescence is very essential for achieving the optimum optical properties. Temperature dependent (15 300 K) photoluminescence has been used to understand nonradiative relaxation of excited carriers. Thermally activated processes and multiple phonons scattering is thoroughly investigated to understand the quenching of photoluminescence with temperature. The strength of exciton-phonon coupling is investigated which determines the variation in energy bandgap of QDs with temperature. Role of exciton phonon scattering is also discussed to understand the basic physics of photoluminescence line width broadening in QDs.
Chapter 4 and 5: This part of thesis focuses on the size and temperature pho-toluminescence properties of near infra red emitting ternary alloyed CdHgTe and Ag2S QDs. Near infrared emitting semiconductor quantum dots (QDs) have attracted significant scientific and technological interests due to their potential applications in the fields of photosensor, solar energy harvesting cells, telecommunication and biological tissue imaging etc. Structural and photophysical properties of CdHgTe QDs have been analyzed by high resolution transmission electron microscopy, X rayphotoelectron microscopy, photoluminescence decay kinetics and low temperature photoluminescence. Investigations on the nonradiative recombinations through trap/defects states and exciton phonon coupling are carried out in colloidal Ag 2S QDs which emits in the range of 1065 1260 nm. Particularly, the photoluminescence
quenching mechanism with increasing temperature is analyzed in the presence of multiple nonradiative relaxation channels, where the excited carriers are thermally stimulated to the surface defect/trap states of QDs.
Chapter 6 and 7: The aim of these chapters is to understand the basic physics of photo induced charge separation in the hybrid systems made from the inorganic QDs with graphene oxide and organic semiconductors. In chapter 6, CdHgTe QDs are decorated on graphene oxide sheets through physisorption. The excited state electronic interactions have been studied by optical and electrical characterizations in these CdHgTe QDs GO hybrid systems. In chapter 7, investigations are carried out for understanding the basic physics of charge separation in the composites of Ag2S QDs and poly (3hexylthiophene 2,5 diyl)(P3HT). These composites of inorganic organic materials are made by simple mixing with help of ultrasonication technique. Steady state and time resolved photoluminescence measurements are used as powerful technique to gain insight of energy/charge transfer process between P3HT and Ag2S QDs. Furthermore, investigations have been carried out on the photoconductivity of the devices made from these hybrid composites keeping the motive of its application in nanotechnology.
Chapter 8: The conclusions of the work presented in this thesis are coherently summarized in this chapter. Thoughts and prospective for future directions are also summed up.
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Cheyne, Robert Bruce. "Self-assembly of polystyrene-poly(ethylene oxide) block copolymers and polymer-stabilized cadmium sulfide nanoparticles at the air-water interface : patterning surface features from the bottom up." 2005. http://hdl.handle.net/1828/799.
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Singh, Tejinder. "Atomic-scale Modeling of Transition-metal Doping of Semiconductor Nanocrystals." 2011. https://scholarworks.umass.edu/open_access_dissertations/356.
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Doping in bulk semiconductors (e.g., n- or p- type doping in silicon) allows for precise control of their properties and forms the basis for the development of electronic and photovoltaic devices. Recently, there have been reports on the successful synthesis of doped semiconductor nanocrystals (or quantum dots) for potential applications in solar cells and spintronics. For example, nanocrystals of ZnSe (with zinc-blende lattice structure) and CdSe and ZnO (with wurtzite lattice structure) have been doped successfully with transition-metal (TM) elements (Mn, Co, or Ni). Despite the recent progress, however, the underlying mechanisms of doping in colloidal nanocrystals are not well understood. This thesis reports a comprehensive theoretical analysis toward a fundamental kinetic and thermodynamic understanding of doping in ZnO, CdSe, and ZnSe quantum dots based on first-principles density-functional theory (DFT) calculations. The theoretical predictions of this thesis are consistent with experimental measurements and provide fundamental interpretations for the experimental observations. The mechanisms of doping of colloidal ZnO nanocrystals with the TM elements Mn, Co, and Ni is investigated. The dopant atoms are found to have high binding energies for adsorption onto the Zn-vacancy site of the (0001) basal surface and the O-vacancy site of the (0001) basal surface of ZnO nanocrystals; therefore, these surface vacancies provide viable sites for substitutional doping, which is consistent with experimental measurements. However, the doping efficiencies are affected by the strong tendencies of the TM dopants to segregate at the nanocrystal surface facets, as indicated by the corresponding computed dopant surface segregation energy profiles. Furthermore, using the Mn doping of CdSe as a case study, the effect of nanocrystal size on doping efficiency is explored. It is shown that Mn adsorption onto small clusters of CdSe is characterized by high binding energies, which, in conjunction with the Mn surface segregation characteristics on CdSe nanocrystals, explains experimental reports of high doping efficiency for small-size CdSe clusters. In addition, this thesis presents a systematic analysis of TM doping in ZnSe nanocrystals. The analysis focuses on the adsorption and surface segregation of Mn dopants on ZnSe nanocrystal surface facets, as well as dopant-induced nanocrystal morphological transitions, and leads to a fundamental understanding of the underlying mechanisms of dopant incorporation into growing nanocrystals. Both surface kinetics (dopant adsorption onto the nanocrystal surface facets) and thermodynamics (dopant surface segregation) are found to have a significant effect on the doping efficiencies in ZnSe nanocrystals. The analysis also elucidates the important role in determining the doping efficiency of ZnSe nanocrystals played by the chemical potentials of the growth precursor species, which determine the surface structure and morphology of the nanocrystals.
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Su, Yu-Wei. "CdS nanocrystalline thin films deposited by the continuous microreactor-assisted solution deposition (MASD) process : growth mechanisms and film characterizations." Thesis, 2011. http://hdl.handle.net/1957/26737.
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The continuous microreactor-assisted solution deposition (MASD) process was used for the deposition of CdS thin films on fluorine-doped tin oxide (FTO) glass. The MASD system, including a T-junction micromixer and a microchannel heat exchanger is capable of isolating the homogeneous particle precipitation from the heterogeneous surface reaction. The results show a dense nanocrystallite CdS thin films with a preferred orientation at (111) plane. Focused-ion-beam was used for TEM specimen preparation to characterize the interfacial microstructure of CdS and FTO layers. The band gap of the microreactor-assisted deposited CdS film was determined at 2.44 eV. X-ray Photon Spectroscopy show the bindings of energies of Cd 3d₃/₂, Cd 3d₅/₂, S 2p₃/₂ and S 2p₁/₂ at 411.7 eV, 404.8 eV, 162.1 eV, and 163.4 eV, respectively.
The film growth kinetics was studied by measuring the film thickness deposited from 1 minute to 15 minutes in physical (FIB-TEM) and optical (reflectance spectroscopy) approaches. A growth model that accounts for the residence time in the microchannel using empirical factor (η) obtained from previous reported experimental data. Applying this factor in the proposed modified growth model gives a surface reaction rate of 1.61*10⁶ cm⁴ mole⁻¹s⁻¹, which is considerable higher than the surface reaction rates obtained from the batch CBD process. With the feature of separating homogeneous and heterogeneous surface reaction, the MASD process provides the capability to tailor the surface film growth rate and avoid the saturation growth regime in the batch process.
An in situ spectroscopy technique was used to measure the UV-Vis absorption spectra of CdS nanoparticles formed within the continuous flow microreactor. The spectra were analyzed by fitting the sum of three Gaussian functions and one exponential function in order to calculate the nanoparticle size. This deconvolution analysis shows the formation of CdS nanoparticles range from 1.13 nm to 1.26 nm using a residence time from 0.26 s to 3.96 s. Barrier controlled coalescence mechanism seems to be a reasonable model to explain the experimental UV-Vis data obtained from the continuous flow microreactor, with a rate constant k' value of 2.872 s⁻¹. Using CFD, low skewness value of the RTD curve at high flow rate (short τ) suggests good radial mixing at high flow rate is responsible for the formation of smaller CdS nanoparticles with a narrower size distribution.
The combination of CdS nanoparticle solution with MASD process resulted in the hindrance of CdS thin film deposition. It is hypothesized that the pre-existing sulfide (S²⁻) ions and CdS nanoparticles changes the chemical species equilibrium of thiourea hydrolysis reaction. Consequently, the lack of thiourea slows down the heterogeneous surface reaction.
To test the scalability of the MASD process, a flow cell and reel-to-reel (R2R)-MASD system were setup and demonstrated for the deposition of CdS films on the FTO glass (6" x 6") substrate. The film deposition kinetics was found to be sensitive to the flow conditions within the heat exchanger and the substrate flow cell. The growth kinetics of the CdS films deposited by R2R-MASD process was investigated by with a deposition time of 2.5 min, 6.3 min, and 9 min. In comparison with the continuous MASD process, the growth rate in R2R-MASD is higher, however more difficult to obtain a linear relationship with the deposition time.Graduation date: 2012
Access restricted to the OSU Community at author's request from Jan. 13, 2012 - Jan. 13, 2013
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Lin, Yuan-Ching, and 林鳶青. "Cadmium Adsorption Using Citrate/Fe(III)、Silicate/Fe(III) Synthetic Iron Oxides." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/84583597858563279756.
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碩士輔英科技大學
環境工程與科學系碩士班
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The objective of this research is to develop the adsorptive material through specific synthetic process. Synthetic processes were divided into two reaction systems, including citrate/Fe(III) and silicate/Fe(III) solutions. And the synthetic conditions of citrate/Fe(III) and silicate/Fe(III) solutions were controlled at pH=8.0, 25℃ and N2 environment. Surface characteristics and microstructures of synthetic iron oxide were investigated, and the adsorption characteristics for metal ions removal were evaluated from water. The quantity of citrate or silicate in synthetic solution was found to have a noticeable effect on the pore size distribution for synthetic iron oxide. Moreover, the macro pores on the surface of synthetic iron oxide decreased after adsorbing cadmium ions. This result indicated that cadmium ions could transport and diffuse into the macro pores on synthetic iron oxide surface, and caused the adsorption reaction. According to XRD analysis result, there was no specific absorption peak appearance on the sample of synthetic iron oxide through the synthetic process under the pure Fe(III) or 0.1 molar ratio of silicate/Fe(III) solution at pH=8.0. The mineralogy of synthetic material prepared by this procedure was verified to be the amorphous iron oxide. However, the mineralogy of synthetic material belonged to the crystalline magnetite through a 0.1 molar ratio of citrate/Fe(III) solution at pH=8.0. Results of kinetic adsorption experiments showed that the best adsorption capabilities of adsorptive material were synthesized under the conditions of 0.1 and 1.0 molar ratio for citrate/Fe(III) and silicate/Fe(III), respectively. And the adsorption efficiencies of cadmium ions for two synthetic materials reached 50~90% and 50~60% at Cd(II)=1.0×10-4M、2.5×10-4M and 5.0×10-4M, pH=6.0, respectively. FTIR analysis result showed that there was a specific absorption peak appearance on iron oxide after reacting with cadmium ions. This result inferred that the adsorptive reaction belonged to form chemical bonding between cadmium ions and iron oxide surface.
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Oehlstrom, Karsten [Verfasser]. "Präparation und Charakterisierung von Cadmium-Stannat als alternatives transparentes leitfähiges Oxid / Karsten Oehlstrom." 2002. http://d-nb.info/96797948X/34.
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