Dissertations / Theses on the topic 'Cerium oxide films'
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Maksimchuk, N. "Nanocrystalline Cerium Oxide Films for Microelectronic Biosensor Transducers." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/34964.
Full textCzerwinski, Franciszek. "The growth and structure of thin oxide films on nickel superficially modified with ceria and cerium." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ36967.pdf.
Full textPham, Nam Hung. "Liquid-injection atomic layer deposition of cerium-doped hafnium oxide dielectric films." Thesis, University of Liverpool, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539745.
Full textMian, A. R. "Some electronic properties of thin dielectric oxide films containing cerium, niobium, vanadium and silicon." Thesis, Brunel University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384096.
Full textKuchibhatla, Satyanarayana. "PROBING AND TUNING THE SIZE, MORPHOLOGY, CHEMISTRY AND STRUCTURE OF NANOSCALE CERIUM OXIDE." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4250.
Full textPh.D.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science & Engr PhD
Göbel, Marcus [Verfasser], and Joachim [Akademischer Betreuer] Maier. "Boundary effects on the electrical conductivity of cerium oxide thin films / Marcus Göbel. Betreuer: Joachim Maier." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2013. http://d-nb.info/1032899611/34.
Full textNguyen, Ty, and ty nguyen@csiro au. "Preparation, Characterisation and Cell Testing of Gadolinium Doped Cerium Electrolyte Thin Films for Solid Oxide Fuel Cell Applications." RMIT University. Electrical and Computer Engineering, 2008. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20081030.110755.
Full textStefanik, Todd Stanley 1973. "The effect of oxygen partial pressure on the epitaxy of cerium oxide films deposited on nickel substrates." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/47650.
Full textJames, Jemy. "Refractive index engineering using polymer nanocomposites Surface engineering of polystyrene–cerium oxide nanocomposite thin films for refractive index enhancement." Thesis, Lorient, 2019. http://www.theses.fr/2019LORIS552.
Full textHistorically, light was a centre of interest for numerous inquisitive people: the philosophers who were interested in its nature and the scientists who wanted to interpret its associated phenomena. Optics is playing a pivotal role in many of our day to day applications.The refractive index is one of the most significant parameters in photonics. An increase in the efficiency of the photonic devices, like Light Emitting Diodes, Solar Cells, etc., can be achieved by reducing the refractive index mismatch of materials used in the optical devices.This thesis throws some light into the tailoring the refractive index of materials, by giving detailed aspects of refractive index and engineering of the refractive index using polymer nanocomposite. This introductory chapter evolves into a wider discussion on the refractive index and the types of refractive index and the potential leverage that can be obtained by engineering the refractive index. Polymer thin films were prepared and the nanoparticles were introduced so as to modify the refractive index. Similarly, thick polymer films were prepared using PMMA and Polystyrene and these were utilized to optically and morphologically characterize the prepared samples. Multiple methods have been utilized to prepare the polymer films. Ultra thin polymer films were also prepared using the spin coating technique and later the thickness of the polystyrene film was changed so as to understand its impact on the refractive index. There were multiple challenges to overcome while carrying out the research like the preparation of ultra pure substrate, uniformity in the prepared polymer thin film, adherence of the polymer thin film on to the substrates after solvent casting etc. All the challenges were overcome using the innovations, which are detailed in the thesis
Weimmerskirch, Jennifer. "Propriétés de luminescence et caractérisation structurale de films minces d'oxydes de silicium dopés au cérium et codopés cérium-ytterbium." Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0180/document.
Full textThis thesis concerns the structural characterization and the photoluminescence properties of thin silicon oxide films doped with rare earths The films are doped with cerium. The co-doping with both cerium and ytterbium is also studied in the case of SiO 2 layers. It is shown that in oxides with composition SiO1, cerium plays an important role in the structure and chemical organization of the oxide, in particular by promoting phase separation of the oxide. The exposure to a focused laser beam generates a local demixtion favored by cerium. For thin SiO1,5 films containing both cerium and silicon nanocrystals, we are able to follow the phase separation occuring between Si nanocrystals and Ce rich aggregates using both atom probe tomography and scanning transmission electron microscopy. The luminescence properties of dopants are discussed in connection with the microstructure of the host matrix. For all these systems, the formation of a cerium silicate with composition Ce2Si2O7 is observed at high temperature (> 1100 ° C). The cerium present either as isolated Ce3+ ions or in a silicate emits intensely at 400 nm (blue) at room temperature, which might be of interest for the development of blue light emitting diodes fully compatible with the Si technology. Finally, an energy transfer from Ce3+ ions to Yb3+ ions is demonstrated in thin SiO2 films opening the route to possible applications in the field of photovoltaics
Hild, Florent. "Étude de la structure et des propriétés optiques de couches minces d’oxydes d’étain dopés avec des terres rares (Ce, Tb, Yb)." Thesis, Université de Lorraine, 2016. http://www.theses.fr/2016LORR0294/document.
Full textThis thesis concerns the structural characterization and the photoluminescence properties of tin oxide thin films doped with rare earths. The films are doped with cerium, terbium and ytterbium. The films were obtained by evaporation of SnO2 on silicon substrates. The as-deposited films were sub-stoichiometric and the films were then annealed in air at 600°C to reach rutile phase. The microstructural study reveals a substrate oxidation leading to a chemical reaction between tin oxide and silicon, and a complex microstructure. To limit the chemical interaction during annealing, silicon substrate coated with thermal silica were used. Undoped films show a broad luminescent band, which is discussed and linked with the microstructure. On the other hand, the structural study of doped films demonstrated the crystallization of a second phase of SnO2, which is orthorhombic. A STEM-EELS study allow to localize the rare earths ions in the films. Finally, the luminescence properties of the rare earths were study with respect to their concentration and the temperature of annealing. After annealing at 700°C, the Tb-doped films emit intensively in the green region, which might be of interest for the development of SnO2-based green light emitting diodes
Tang, Ling. "MODIFICATION OF SOLID OXIDE FUEL CELL ANODES WITH CERIUM OXIDE COATINGS." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1244252739.
Full textSantos, Camila Paixão [UNESP]. "Fabricação e caracterização de filmes espessos de CeO2 puro para aplicação em sensores de gás." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/144639.
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Este trabalho apresenta e discute o uso do óxido de cério na fabricação de filmes espessos por “screen printing” para aplicações em sensores de gás. Nesse estudo o CeO2 puro foi obtido pelo método dos precursores poliméricos utilizando como resina precursora o citrato de céria. O “puff” – espuma resultante da primeira fase do tratamento térmico da resina- foi calcinado a 550, 600, 700 e 750°C. O pó foi caracterizado por termogravimetria (TG) e as propriedades estruturais, morfológicas foram avaliadas por difratometria de raios X (DRX), espectroscopia Raman, área de superfície por isotermas Brunauer, Emmett e Taller (BET) e microscopia eletrônica de varredura (MEV). A resposta sensora foi estudada em uma câmara de teste construída no Laboratório de Catálise e Superfícies do Instituto de Ciência de Tecnologia de Materiais (INTEMA) da Universidade de Mar del Plata. A TG mostrou a formação de óxido de cério a 550°C, temperatura relativamente baixa quando comparada com outros métodos. Mediante DRX todas as amostras mostraram picos correspondentes à fase pura de CeO2 o qual cristaliza em uma estrutura cúbica do tipo fluorita, entretanto, maiores temperaturas de calcinação mostraram aumento da cristalinidade e tamanho do cristalito. No espectro Raman, um forte pico em torno do 461 cm-1 foi detectado, atribuído às vibrações simétricas do Ce-O. A área de superfície BET dos pós foi de 301, 77 m2/g o que evidencia a formação de partículas muito pequenas e altamente reativas. As micrografias obtidas por MEV mostram a presença de diferentes tamanhos na forma de aglomerados. A caracterização da resposta sensora mostrou que o sensor fabricado a partir de pós de CeO2 puro apresenta um bom tempo de resposta, alcançando a melhor performance com temperatura de trabalho de 400 °C, tanto em atmosferas redutoras e oxidantes. A característica principal observada foi que os resultados são dependentes dos ciclos anteriores, a reprodutibilidade do sistema é garantida quando se apaga a “memória” do sistema, expondo-o ao vácuo.
This paper presents and discusses the use of cerium oxide in the production of thick films for "screen printing" for applications in gas sensors. In this study the pure CeO2 was obtained by the polymeric precursor method using as a precursor resin citrate ceria. The "puff" - resulting foam from the first stage of thermal treatment of the resin-calcined at 550, 600, 700 and 750 °C. The powder was characterized by thermogravimetry (TG) and structural, morphological were evaluated by X-ray diffraction (XRD), Raman spectroscopy, isothermal Brunauer surface area, Emmett and Taller (BET) and scanning electron microscopy (SEM) . The sensor response was studied in a test chamber built in the Laboratory of Catalysis and Surface Materials Technology Institute of Science (INTEMA), University of Mar del Plata. The thermogravimetry showed the formation of cerium oxide at 550° C, relatively low temperature compared with other methods. Upon XRD all samples showed peaks corresponding to pure CeO2 phase which crystallizes in a cubic fluorite type structure, however, higher calcination temperatures showed increased crystallinity and crystallite size. In the Raman spectrum, a strong peak around 461 cm-1 was detected, assigned to symmetric vibrations of the Ce-O. The BET surface area of the powders was 301, 77 m2 /g which shows the formation of very small and highly reactive particles. The SEM micrographs show the presence of different sizes in the form of agglomerates. The characterization of the sensor response showed that the sensors manufactured from pure CeO2 powder has a good response time, achieving better performance at 400 °C working temperature in both reducing and oxidizing atmospheres. The main feature observed was that the results are dependent on previous cycles, the system reproducibility is guaranteed when it deletes the "memory" of the system, exposing it to vacuum.
Santos, Camila Paixão. "Fabricação e caracterização de filmes espessos de CeO2 puro para aplicação em sensores de gás /." Guaratinguetá, 2016. http://hdl.handle.net/11449/144639.
Full textCoorientadora: Maria Olívia Berengue
Banca: José Vitor Candido de Souza
Banca: Miguel Adolfo Ponce
Resumo: Este trabalho apresenta e discute o uso do óxido de cério na fabricação de filmes espessos por "screen printing" para aplicações em sensores de gás. Nesse estudo o CeO2 puro foi obtido pelo método dos precursores poliméricos utilizando como resina precursora o citrato de céria. O "puff" - espuma resultante da primeira fase do tratamento térmico da resina- foi calcinado a 550, 600, 700 e 750°C. O pó foi caracterizado por termogravimetria (TG) e as propriedades estruturais, morfológicas foram avaliadas por difratometria de raios X (DRX), espectroscopia Raman, área de superfície por isotermas Brunauer, Emmett e Taller (BET) e microscopia eletrônica de varredura (MEV). A resposta sensora foi estudada em uma câmara de teste construída no Laboratório de Catálise e Superfícies do Instituto de Ciência de Tecnologia de Materiais (INTEMA) da Universidade de Mar del Plata. A TG mostrou a formação de óxido de cério a 550°C, temperatura relativamente baixa quando comparada com outros métodos. Mediante DRX todas as amostras mostraram picos correspondentes à fase pura de CeO2 o qual cristaliza em uma estrutura cúbica do tipo fluorita, entretanto, maiores temperaturas de calcinação mostraram aumento da cristalinidade e tamanho do cristalito. No espectro Raman, um forte pico em torno do 461 cm-1 foi detectado, atribuído às vibrações simétricas do Ce-O. A área de superfície BET dos pós foi de 301, 77 m2/g o que evidencia a formação de partículas muito pequenas e altamente reativas. As microgra... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This paper presents and discusses the use of cerium oxide in the production of thick films for "screen printing" for applications in gas sensors. In this study the pure CeO2 was obtained by the polymeric precursor method using as a precursor resin citrate ceria. The "puff" - resulting foam from the first stage of thermal treatment of the resin-calcined at 550, 600, 700 and 750 °C. The powder was characterized by thermogravimetry (TG) and structural, morphological were evaluated by X-ray diffraction (XRD), Raman spectroscopy, isothermal Brunauer surface area, Emmett and Taller (BET) and scanning electron microscopy (SEM) . The sensor response was studied in a test chamber built in the Laboratory of Catalysis and Surface Materials Technology Institute of Science (INTEMA), University of Mar del Plata. The thermogravimetry showed the formation of cerium oxide at 550° C, relatively low temperature compared with other methods. Upon XRD all samples showed peaks corresponding to pure CeO2 phase which crystallizes in a cubic fluorite type structure, however, higher calcination temperatures showed increased crystallinity and crystallite size. In the Raman spectrum, a strong peak around 461 cm-1 was detected, assigned to symmetric vibrations of the Ce-O. The BET surface area of the powders was 301, 77 m2 /g which shows the formation of very small and highly reactive particles. The SEM micrographs show the presence of different sizes in the form of agglomerates. The characterization of the sensor response showed that the sensors manufactured from pure CeO2 powder has a good response time, achieving better performance at 400 °C working temperature in both reducing and oxidizing atmospheres. The main feature observed was that the results are dependent on previous cycles, the system reproducibility is guaranteed when it deletes the "memory" of the system, exposing it to vacuum
Mestre
Lavková, Jaroslava. "Electron microscopy and spectroscopy study of nanostructured thin film catalysts for micro-fuel cell application." Thesis, Dijon, 2016. http://www.theses.fr/2016DIJOS049/document.
Full textPresent doctoral thesis is focused on investigation of novel metal-oxide anode catalyst for fuel cell application by electron microscopy and associated spectroscopies. Catalysts based on Pt-doped cerium oxide in form of thin layers prepared by simultaneous magnetron sputtering deposition on intermediate carbonaceous films grown on silicon substrate have been studied. The influence of the catalyst support composition (a-C and CNx films), deposition time of CeOx layer and other deposition parameters, as deposition rate, composition of working atmosphere and Pt concentration on the morphology of Pt-CeOx layers has been investigated mainly by Transmission Electron Microscopy (TEM). The obtained results have shown that by combination of suitable preparation conditions we are able to tune the final morphology and composition of the catalysts. The composition of carbonaceous films and Pt-CeOx layers was examined by complementary spectroscopy techniques – Energy Dispersive X-ray Spectroscopy (EDX), Electron Energy Loss Spectroscopy (EELS) and X-ray Photoelectron Spectroscopy (XPS). Such prepared porous structures of Pt-CeOx are promising as anode catalytic material for real fuel cell application
Předložená dizertační práce se zabývá studiem nových katalyzátorů na bázi kov-oxid vhodných pro použití v palivových článcích na straně anody. Platinou dopovaný oxid ceru připravený magnetronovým naprašováním ve formě tenkých vrstev na uhlíkových mezivrstvách nesených křemíkovým substrátem byl zkoumán prostřednictvím mikroskopických a spektroskopických metod. Vliv složení uhlíkového nosiče (a-C a CNx filmy), depozičního času CeOx vrstvy a dalších depozičních parametrů, např. depoziční rychlosti, složení pracovní atmosféry a Pt koncentrace na morfologii Pt-CeOx vrstev byl studován převážně pomocí transmisní elektronové mikroskopie (TEM). Získané výsledky ukazují, že vhodnou kombinací depozičních podmínek jsme schopni vyladit výslednou morfologii a kompozici katalyzátoru. Složení uhlíkových filmů a Pt-CeOx vrstev bylo studováno spektroskopickými technikami – energiově-disperzní spektroskopií (EDX), spektroskopií charakteristických ztrát elektronů (EELS) a rentgenovou fotoelektronovou spektroskopií (XPS). Takto připravené porézní struktury vrstev Pt-CeOx jsou slibným katalytickým materiálem na straně anody pro reálné aplikace v palivových článcích
Mesguich, David. "Elaboration de matériaux nanostructurés pour piles à combustible SOFC : application à Nd2NiO4+d et Ce1-xAxO2-y." Thesis, Bordeaux 1, 2010. http://www.theses.fr/2010BOR14036/document.
Full textThe ongoing development of Intermediate Temperature Solid Oxide Fuel Cells implies the optimization of the synthesis and deposition methods for the new materials developed these past years. Indeed, electrochemical properties of these materials are closely linked to the initial powder characteristics as well as the electrode (or electrolyte) microstructure after deposition. Significant improvement of the aforementioned properties can be obtained via nanostructuration of the materials. Thus, this thesis is dedicated to the synthesis of the cathode material Nd2NiO4+d and the electrolyte material Ce1-xAxO2-d. Methods employed are namely nanopowder synthesis in water/ethanol supercritical mixtures and spray pyrolysis as well as thin film deposition in supercritical fluids. The obtained objects have finally been characterized by electrochemical impedance spectroscopy in order to assess their performance for the SOFC application
Максимчук, Наталія Володимирівна. "Плівки оксиду церію для біосенсорів токсичних речовин." Doctoral thesis, 2012. https://ela.kpi.ua/handle/123456789/1705.
Full textKubát, Jan. "Epitaxní vrstvy oxidu ceru pro optoelektroniku." Master's thesis, 2020. http://www.nusl.cz/ntk/nusl-434890.
Full textStetsovych, Vitalii. "Experimentální kontrola koncentrace iontů Ce3+ v modeloých katalyzátorech na bázi oxidu ceru." Doctoral thesis, 2015. http://www.nusl.cz/ntk/nusl-349365.
Full textKúš, Peter. "Studium interakce Pd a Pt s oxidy cínu a ceru." Master's thesis, 2013. http://www.nusl.cz/ntk/nusl-324567.
Full textChung, Cheng-Hung, and 鍾振泓. "Fabrication and Investigation of Anode-supported Intermediate Temperature Solid Oxide Fuel Cells with Composite Ceria-based Electrolyte Films." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/02103700146146232649.
Full text國立臺灣大學
化學研究所
96
Ce0.8Gd0.2O2-δ (CGO) powder samples were synthesized using citrate sol-gel combustion method, and then the composite electrolyte materials were prepared by a small amount of 1mol% Bi2O3, GeO2, Nb2O5 to CGO. The results show that the densification and conductivity of composite electrolyte were improved. In addition, undergoing 10% H2/N2 for ~ 85h, the conductivity at 700°C in air of the samples could be retained nearly at their starting conductivity. The fabrication of anode-supported intermediate temperature solid oxide fuel cell (IT-SOFC) was carry out by using sandwiched dry-pressed technique with flour layers, because of humid environment in Taiwan, ultrafine CGO powder as electrolyte material. The single cell showed that electrolyte was 16 ± 2 μm in most thin thickness, anode (60wt%-NiO/CGO) and cathode (La0.8Sr0.2Co0.8Fe0.2O3-δ) were 493 ± 7 and 152 ± 4 μm in thickness, respectively. At our best knowledge to build the electrochemical testing device, and the performances of single cell were ~ 450 mW/cm2 (PPD) and ~ 0.79V (OCV), while 100%H2 and air with optimum flow rate of 50 and 150 mL/min at 700°C. On the other hand, under 100%H2 and 100%O2 with optimum flow rate of 50 and 90 mL/min, the the performances were ~ 504 mW/cm2 and ~ 0.82V. The rate-determining step (RDS) was depended on operation temperature: Under 550°C, RDS was oxygen reduction reaction. Above 600°C, RDS was ohmic loss. To exchange of electrolyte material, the addition of 1mol% GeO2 to CGO film was made, under the optimum flow rate through air and 100%O2 in turn, the PPD of single cell were ~ 462 and ~ 521 mW/cm2, respectively, which were improving ~ 12 and ~ 17 mW/cm2, respectively. To exchange of cathode material, the addition of 5.02wt% Pt to LSCF cathode was made, under the optimum flow rate through air and 100%O2 in turn, the PPD of single cell were ~ 526 and ~ 582 mW/cm2, respectively, which were improving ~ 76 and ~ 78 mA/cm2, respectively. To exchange of anode material, the addition of 2.5wt% Mn to Ni/CGO anode was made, under flow rate of 5mL/min through 100%H2 and 100%CH4 at 700°C in turn, the sample displayed about one-third and three-fifth times of the performances of pure Ni/CGO anode, in addition, the performance decreased with long-time. The primary reasons were suggested following: the addition of 1mol% GeO2 to CGO was improving oxide-ion conductivity of electrolyte, thus the influence improved the performance of single cell. However, a small amount of 1mol% Bi2O3 or Nb2O5 to CGO was deteriorating short-circuit short-circuit of electrolyte. For composite Pt/LSCF cathode, the adequate amount of Pt to LSCF was selected due to low oxide-ion conductivity and optimum microstructure surface of self. For composite Mn-Ni/CGO anode, the dense microstructure on surface was observed by the addition of Mn to Ni/CGO , thus the performance of single cell was deteriorating for the direct electrochemical oxidation of methane.
Wilkens, Henrik. "Phase transitions of rare earth oxide films grown on Si(111)." Doctoral thesis, 2014. https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2014032112319.
Full text