Tesis sobre el tema "Bismuth Based Materials"
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Cadevall, Riera Miquel. "Bismuth based (nano)materials and platforms for (bio)sensing". Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/285769.
Texto completoThe thesis is focused on the fabrication of new sensing and biosensing platforms for pollutants detection. Although bismuth-based micro and nanomaterials seem to be the appropriated materials to achieve this objective nevertheless new platforms including for example those based on paper are also proposed. In the first chapter the main objectives of this thesis are described in detail. The introduction part (chapter 2) of this thesis is dedicated to the revision of the recent reports / achievements on bismuth-based nanomaterials in different application fields that include medicine, photodegradation of organic pollutants, cosmetics, pigments and alloys. An important section of this part is focused on the description of the effect of bismuth-based materials in heavy metals and biosensing applications. Bismuth nanoparticles are found as an innovative material in heavy metals sensing and biosensing applications. A study on the effect of the modification of screen-printed electrodes with bismuth nanoparticles and its use for the heavy metal detection is shown (chapter 3). Different modifications of polyol based bismuth nanoparticles synthesis have been evaluated in aim to obtain the more efficient nanoparticles with interest in heavy metal sensing. In addition the results obtained for the detection of lead and cadmium is also shown in the same chapter. In the chapter 4 a new electrode modification strategy is presented. This new strategy is based on the use of magnetic core/shell bismuth nanoparticles. Taking advantages of the bismuth oxide presence onto the shell of these nanoparticles, heavy metal detection in different On-Off sensing platforms is shown. The modification of electrodes is clearly demonstrated by doing cycles with both modification and cleaning of the electrodes obtaining a kind of digital (On-Off) response of heavy metals. To solve sampling and sample pretreatment issues a heavy metal sensing platform that uses a paper-based lateral flow chip is also developed and described at chapter 5. Fabrication and the optimization of this new heavy metal sensor are shown; it takes advantage of the use of a filter paper substrate. This new platform is capable to detect lead and cadmium in different matrixes including mud. In the last chapter (chapter 6), the integration of bismuth nanoparticles into a phenol biosensing system is shown. It takes advantages of the use of tyrosinase enzyme which brings certain selectivity in phenolic compounds detection. Morphological and electrochemical characterizations of the developed biosensor also are shown in this chapter. The developed biosensor shows good performance in catechol detection. Finally in the chapter 7 the general conclusions and some future perspectives are given.
Zhang, Liping. "Development of Bismuth Oxide-Based Materials for Iodide Capture and Photocatalysis". Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1542652670479038.
Texto completoBack, Michele <1984>. "Bismuth-based advanced luminescent (nano)materials: from design to application". Doctoral thesis, Università Ca' Foscari Venezia, 2016. http://hdl.handle.net/10579/10319.
Texto completoWhite, John B. "Application of Thermomechanical Characterization Techniques to Bismuth Telluride Based Thermoelectric Materials". Thesis, University of North Texas, 2002. https://digital.library.unt.edu/ark:/67531/metadc3166/.
Texto completoMortensen, Clay Dustin. "The effect of grain size, alloy composition and turbostratic disorder on the thermal and electrical properties of Bi₂Te₃ based materials /". Connect to title (abstract only) online (ProQuest), 2008. http://proquest.umi.com/pqdweb?did=1690937581&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.
Texto completoZanella, Sofia <1993>. "Luminescent materials based on lanthanide doped bismuth oxyfluoride particles for nanophosphor and nanothermometer applications". Master's Degree Thesis, Università Ca' Foscari Venezia, 2019. http://hdl.handle.net/10579/14410.
Texto completoKarlsson, Viktor. "Thermoelectric Cooler Prototype Based on Bismuth Telluride and Aimed for Space Applications". Thesis, Uppsala universitet, Tillämpad materialvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-337295.
Texto completoHutton, William Antony D. I. "Investigations into the structure, thermal stability and electrical properties of various bismuth-based oxides, including Sillenite materials". Thesis, University of Sheffield, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419264.
Texto completoOrdon, Karolina. "Functionalized semiconducting oxides based on bismuth vanadate with anchored organic dye molecules for photoactive applications". Thesis, Le Mans, 2018. http://www.theses.fr/2018LEMA1006/document.
Texto completoThe search for new materials as photocatalysts invisible light for the depollution of the environment (waters, atmospheres) is a very active field of research and attracts the interest of a large scientific community in Physics, Chemistry and Materials Science. Recent research developpements are conducted to improve the photocatalytic efficiency of certain classes of known photoactive materials, and to develop the synthesis of new functional materials. In this context, photoactive oxide semiconductors based on bismuth vanadate (BiVO4) having an electronic band in the middle of the visible spectrum, offer a serious alternative to efficient conventional photocatalysts (TiO2, ZnO) whose photo-excitation requires only the UV fraction of the solar spectrum.The work done in this thesis is therefore dedicated toBiVO4-based materials in the form of mesoporous architectures or hybrid assemblies associating organic groups with charge transfer processes. Two major contributions have been developed, one of which is the experimental realization of novel mesoporous architectures, functionalized by sensitizing organic groups and the study of their electronic and optical properties in order to optimize their photocatalytic efficiencies. The second part deals with numerical simulations of hybrid nanostructures using approaches as the DFT method, ab-initio or quantum chemistry codes. Model systems have been constructed associating BiVO4nanoclusters (NC) and organic groups (GO). The electronic and optical properties as well as the structural and vibrational characteristics of the systems (NC-GO) were determined and compared with the experimental data. The charge transfer phenomena involved between the organic groups and the inorganic structure were characterized as well as their role in the efficiency of photo-catalytic responses of hybrid systems
Pacher, Fernandes Rodrigo [Verfasser]. "Piezoresponse Force Microscopy study of potassium sodium niobate and bismuth sodium titanate based lead-free ferroelectric materials / Rodrigo Pacher Fernandes". München : Verlag Dr. Hut, 2014. http://d-nb.info/1049362829/34.
Texto completoPerenlei, Ganchimeg. "Energy band engineering of complex metal oxides". Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/90056/1/Ganchimeg_Perenlei_Thesis.pdf.
Texto completoVerosky, Mark. "Performance of Marlow Materials in a Transverse Peltier Cooler". The Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1586184457147283.
Texto completoMeng, Xiangchao. "Enhanced Bismuth-based Photocatalysis Applied to Environmental Remediation". Thesis, Université d'Ottawa / University of Ottawa, 2018. http://hdl.handle.net/10393/38064.
Texto completoNeves, Márcia Carvalho. "Novos pigmentos à base de bismuto". Master's thesis, Universidade de Aveiro, 2002. http://hdl.handle.net/10773/21904.
Texto completoNos dias de hoje são inúmeras as aplicações dadas aos materiais à base de bismuto. As aplicações situam-se em áreas tão distintas como a medicina, metalurgia, cosmética e farmácia, tintas e vernizes. Por exemplo na área dos pigmentos colorantes, prevê-se que o BiVO4 venha a ter uma importância comercial crescente dado ser o mais promissor substituinte dos pigmentos amarelos contendo chumbo e cádmio. O principal problema na utilização de pigmentos à base de bismuto reside no facto destes compostos serem geralmente dispendiosos. Neste trabalho investigam-se métodos alternativos na preparação e utilização destes pigmentos, potenciando a sua utilização de um modo mais competitivo. Investigou-se a preparação de revestimentos de BiVO4 pelo processo de deposição química em solução (CBD: Chemical Bath Deposition) em substratos de vidro. Procurou-se adaptar este novo método de preparação de BiVO4, na formação de partículas compósitas utilizando o ZnO como material de suporte. O processo de deposição química foi investigado pela caracterização detalhada quer dos materiais sólidos obtidos quer pela monitorização espectroscópica das soluções sobrenadantes. Estudou-se a incorporação de Ce (III) na estrutura do BiVO4. Os filmes obtidos foram caracterizados, nomeadamente no que diz respeito às suas propriedades cromáticas, estruturais e morfológicas. Os nanocompósitos polímero-inorgânico têm sido largamente investigados devido às suas potenciais aplicações como materiais compatíveis a elevadas temperaturas ou como revestimentos poliméricos reforçados com partículas. Investigou-se a utilização de nanopartículas de Bi2S3 como cargas no fabrico de nanocompósitos de matriz polimérica. As propriedades térmicas de nanocompósitos de nylon-6.10 foram especialmente estudadas, tendo em conta as potenciais aplicações do Bi2S3 nanodisperso como retardador de chama. O efeito do tratamento prévio das cargas bem como o efeito do método de preparação do nanocompósito nas propriedades finais do material foram igualmente investigadas.
Bismuth based materials have been used in several applications including in medicine, metallurgy, cosmetics and pigments. Bismuth (III) vanadate (BiVO4) is a solid that presents interesting technological properties as a pigment. This compound is the best candidate to replace toxic yellow pigments, such as cadmium and lead compounds, in some applications. Due to restrictions imposed to the industry on the use of Cd and Pb pigments, it is expected that the commercial importance of BiVO4 continues to increase. It is also true that bismuth pigments are relatively expensive materials, lowering the commercial competitiveness of such pigments. Therefore, there is interest in developing new forms of pigmentation, enabling a more competitive use of Bi containing pigments. Chemistry can provide the tools to create innovative forms of BiVO4 pigmentation by synthesizing BiVO4 based materials with specific optical and morphological properties. A chemical bath deposition method to deposit monoclinic-BiVO4 coatings on glass substrates is presented. The reported method involves the controlled growth of BiVO4 monolayers, at mild temperatures, in the presence of a sequestering agent such as ethylenediaminetetracetic acid (EDTA). We used this CBD method to deposit BiVO4 on other types of substrates of technological interest. The encapsulation of hollow ZnO microparticles with the BiVO4 pigment is reported. The CBD process was investigated by the characterization of the solid fase and by the spectroscopic studies of the solutions. Pigments based on BiVO4 doped with Ce (III) were prepared using the CBD developed. The colour, morphological and structural properties of these pigments were studied. Polymer-inorganic nanocomposites have been of interest due to several applications, such as in tough and high-temperature compatible materials or particle-reinforced polymer coatings. This work presents results concerning the preparation of a novel type of polymer nanocomposites, which contain Bi2S3 nanofibers as fillers. The synthetic approaches to prepare Bi2S3/nylon-6.10 nanocomposites will be discussed in light of the final nanocomposites properties, such as the chemical stability and morphological homogeneity. This work aims to investigate the potential use of such nanomaterials as flame retardant pigments for polymeric materials.
Medeiros, Marta Eloisa. "Estudo de materiais a base de bismuto (III) : sistema Bi2O3-V2O5 modificado pela incorporação de metais alcalinos terrosos". [s.n.], 1995. http://repositorio.unicamp.br/jspui/handle/REPOSIP/249025.
Texto completoTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Doutorado
Schwartzer, Eduardo. "Desenvolvimento e caracterização de um cimento endodôntico experimental a base de resina epóxica com adição de sais de bismuto". reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2011. http://hdl.handle.net/10183/61441.
Texto completoThe aim of this study was the development and evaluating of an experimental endodontic sealer epoxy based after addition of three different bismuth salts, according to the requirements of ISO 6876 and 4049 searching for the composition with better performance. Eighteen groups were formulated with the inclusion of 20%, 40%, 60%, 80%, 100% and 120% of three different bismuth salts, by weight, on epoxy resin. Then, flow tests, working time, setting time, film thickness, dimensional change, sorption and solubility, radiopacity and cytotoxicity were performed. Data were analyzed by two-way ANOVA (type of filler and concentration) and Tukey at a level of significance of 5%. The formulations with bismuth subsalicylate did not show suitable properties. However, cements with bismuth subnitrate and subcarbonate shown to be promising, particularly with regard to formulations containing bismuth subnitrate, wich presented superior results. The addition of 80% salt generated satisfactory radiopacity to subcarbonate and bismuth subnitrate sealers, bismuth subsalicylate had only reached satisfatory radiopacity at 120%. In the cytotoxicity assay none of the formulations showed statistical significance when compared to control. It is concluded that the formulations containing bismuth subnitrate and bismuth subcarbonate have potential use as filler in endodontic sealers.
Lima, Regiane Godoy de [UNESP]. "Síntese de supercondutores cerâmicos à base de bismuto produzidos pelo método Pechini associado ao processo de hidrotermalização assistido por micro-ondas". Universidade Estadual Paulista (UNESP), 2013. http://hdl.handle.net/11449/91978.
Texto completoAs rotas de síntese dos cupratos supercondutores buscam por melhorias em suas propriedades como a obtenção de fases únicas, grãos homogêneos e melhor conectados o que, consequentemente, interfere no aumento da capacidade de transporte de corrente elétrica. Neste trabalho foi estudada a síntese do óxido supercondutor do sistema Bi:Sr:Ca:Cu:O na fase 2212 (BSCCO-2212) que apresenta temperatura crítica em torno de 85 K. Para a síntese desse material, foi utilizada uma variação do método dos precursores poliméricos desenvolvido por Pechini e, em uma segunda rota, foi adicionada, a este método, uma etapa na qual se aplicou o método de hidrotermalização assistida por energia de micro-ondas. Neste último, o material é aquecido de dentro para fora e, devido à interação das micro-ondas com a solução, a temperatura do sistema aumenta rapidamente, influenciando diretamente na velocidade da síntese. Em contraste, no aquecimento convencional, o material é aquecido, primeiramente, na superfície e, só então, ocorre a transferência de calor para o interior do sistema. Os pós resultantes dos dois métodos de síntese ora descritos foram tratados termicamente e, então, prensados para se obter pastilhas. Na sequência, foram feitas caracterizações estruturais, elétricas e magnéticas no intuito de se estudar a influência de cada método sobre as propriedades dos materiais sintetizados.
The synthesis routes of superconducting cuprates seek for the improvement of the proprieties of these materials such as the achievement of pure superconducting phases, homogeneity of the grains, better connectivity between the grains and the increase of the transport current. In this study we synthesized oxide superconductors of the Bi:Sr:Ca:Cu:O system focusing on the 2212 phase (BSCCO-2212) for which the Tc lies on around 85 K. For the productions of this material, it was used two synthesis routes. In one of them it was followed only the polymeric precursor method developed by Pechini and, in the second route, the Microwave-Assisted Hydrothermal method was associated with the Pechini one. For this method the heat of the material is from inside out, i.e., the temperature of the system is increased very fast and, consequently, the velocity of synthesis is increased. In conventional heat treatment the material is heated, firstly, at the surface and then the heat is transferred to the interior of the system. The powders of the materials, which were obtained from the described methods, were heat treated and thus, pressed. After that, structural, electrical and magnetic characterizations were carried out to study the influence of each synthesis method on the properties of the produced superconductors.
Lima, Regiane Godoy de. "Síntese de supercondutores cerâmicos à base de bismuto produzidos pelo método Pechini associado ao processo de hidrotermalização assistido por micro-ondas /". Ilha Solteira, 2013. http://hdl.handle.net/11449/91978.
Texto completoBanca: Agda Eunice de Souza Albas
Banca: Fabiano Colauto
Resumo: As rotas de síntese dos cupratos supercondutores buscam por melhorias em suas propriedades como a obtenção de fases únicas, grãos homogêneos e melhor conectados o que, consequentemente, interfere no aumento da capacidade de transporte de corrente elétrica. Neste trabalho foi estudada a síntese do óxido supercondutor do sistema Bi:Sr:Ca:Cu:O na fase 2212 (BSCCO-2212) que apresenta temperatura crítica em torno de 85 K. Para a síntese desse material, foi utilizada uma variação do método dos precursores poliméricos desenvolvido por Pechini e, em uma segunda rota, foi adicionada, a este método, uma etapa na qual se aplicou o método de hidrotermalização assistida por energia de micro-ondas. Neste último, o material é aquecido de dentro para fora e, devido à interação das micro-ondas com a solução, a temperatura do sistema aumenta rapidamente, influenciando diretamente na velocidade da síntese. Em contraste, no aquecimento convencional, o material é aquecido, primeiramente, na superfície e, só então, ocorre a transferência de calor para o interior do sistema. Os pós resultantes dos dois métodos de síntese ora descritos foram tratados termicamente e, então, prensados para se obter pastilhas. Na sequência, foram feitas caracterizações estruturais, elétricas e magnéticas no intuito de se estudar a influência de cada método sobre as propriedades dos materiais sintetizados.
Abstract: The synthesis routes of superconducting cuprates seek for the improvement of the proprieties of these materials such as the achievement of pure superconducting phases, homogeneity of the grains, better connectivity between the grains and the increase of the transport current. In this study we synthesized oxide superconductors of the Bi:Sr:Ca:Cu:O system focusing on the 2212 phase (BSCCO-2212) for which the Tc lies on around 85 K. For the productions of this material, it was used two synthesis routes. In one of them it was followed only the polymeric precursor method developed by Pechini and, in the second route, the Microwave-Assisted Hydrothermal method was associated with the Pechini one. For this method the heat of the material is from inside out, i.e., the temperature of the system is increased very fast and, consequently, the velocity of synthesis is increased. In conventional heat treatment the material is heated, firstly, at the surface and then the heat is transferred to the interior of the system. The powders of the materials, which were obtained from the described methods, were heat treated and thus, pressed. After that, structural, electrical and magnetic characterizations were carried out to study the influence of each synthesis method on the properties of the produced superconductors.
Mestre
BONTURIM, EVERTON. "Controle de propriedades multiferroicas em filmes finos óxidos dopados com íons terras raras para aplicação como dispositivos lógicos e de memória". reponame:Repositório Institucional do IPEN, 2017. http://repositorio.ipen.br:8080/xmlui/handle/123456789/28033.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Nas últimas décadas, o consumo de dispositivos eletrônicos e a alta demanda por armazenamento de dados tem mostrado grandes oportunidades para a criação de novas tecnologias que garantam as necessidades mundiais na área de computação e desenvolvimento. Alguns materiais multiferroicos tem sido amplamente estudados e o BiFeO3, considerado o único material multiferroico em temperatura ambiente, ganhou destaque como candidato para produção de dispositivos lógicos e de memória. O uso de técnicas de crescimento como a deposição por laser pulsado permitiu a produção de filmes finos de BiFeO3 com elevado controle de qualidade. Heteroestruturas de filmes multiferroicos de BiFeO3 e LaBiFeO3 foram crescidas com diferentes espessuras sobre substratos de SrTiO3(100), DyScO3(110) e SrTiO3/Si(100) para avaliação e teste de suas propriedades elétricas e magnéticas. Filmes ferromagnéticos de Co0,9Fe0,1 foram depositados por sputtering sobre os filmes multiferroicos para avaliação da interação interfacial entre ordenamentos magnéticos. Técnicas como fotolitografia foram utilizadas para padronização de microdispositivos gravados sobre as amostras. Tanto os filmes finos de BiFeO3 como os de LaBiFeO3 foram crescidos epitaxialmente sobre os substratos já cobertos com uma camada buffer de SrRuO3 usado como contato elétrico inferior. A estrutura cristalina romboédrica das ferritas de bismuto foi confirmada pelos dados de difração de raios X, bem como a manutenção de tensão estrutural causada pela rede cristalina do substrato para amostras de 20 nm. Os valores de coeficiente do tensor piezelétrico d33 foram da ordem de 0,15 V (∼ 60 kV.cm-2) para amostras com 20 nm de espessura enquanto que os valores de voltagem coerciva para as análises de histerese elétrica foram da ordem de 0,5 V para as mesmas amostras. A relação de coercividade elétrica com a espessura corresponde ao perfil encontrado na literatura pela relação E≈d-2/3. As amostras de CoFe/BFO e CoFe/LBFO depositadas em diferentes substratos apresentam acoplamento interfacial entre ordenamento ferromagnético e antiferromagnético com momento ferromagnético de rede.
Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
CAPES:99999.009511/2014-08
CNPq:146622/2013-2
Dussarrat, Christian. "Caractérisations cristallographiques et magnétiques de nouvelles phases oxygènées a base de ruthénium. Filiations structurales avec les perovskites". Phd thesis, Université Sciences et Technologies - Bordeaux I, 1996. http://tel.archives-ouvertes.fr/tel-00153325.
Texto completoTu, Yu-Chieh y 涂煜杰. "Bismuth Based Materials for Green Energy". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/91248506580751813202.
Texto completo國立臺灣大學
材料科學與工程學研究所
102
The bismuth-based metal oxides, such as BiFeO3 (BFO) and Bi/B-doped TiO2 are potential candidates for electrolyte of low temperature solid oxide fuel cell and solution processable hybrid solar cell, respectively. In this study, we synthesize bismuth-based metal oxides, and investigate the material characteristics and the cell characteristics. For low temperature solid oxide fuel cells, we prepared BFO as electrolyte. The material was synthesized using solution approach. Bismuth nitrate pentahydrate (Bi(NO3)3.5H2O) and iron nitrate nonahydrate (Fe(NO3)3.9H2O) were dissolved in the mixture of 2-ethoxyethanol and acetic acid at 70°C for 30 min. After evaporating the solvent, the BFO was calcined at 500°C for 2 hrs in air. The air calcined BFO was pressed into a disk which showed a pure BFO perovskite structure after sintered at either 850°C or 900°C. The BFO was coated with 100 micron yttria-stabilized zirconia (YSZ) buffer layer to avoid hydrogen reduction of BFO. This bilayer electrolyte exhibits 1.6 times increasing in maximum power density as compared with pure YSZ due to its perovskite structure, when Ni-YSZ anode and lanthanum strontium cobalt ferrite cathode were used in the fuel cell at 650°C. TiO2 nanorods were synthesized to fabricate hybrid P3HT:TiO2 solar cells. The TiO2 nanorods were synthesized using sol-gel process in the presence of oleic acid surfactant at 98℃ for 9 hrs. The size of TiO2 nanocrystal is about 35 nm in length and 5 nm in diameter. The insulating oleic acid on TiO2 nanorods was replaced by pyridine (as-synthesized TiO2) for good charge transport between P3HT and TiO2 in the application of hybrid P3HT:TiO2 nanorods solar cells. In order to improve the power conversion efficiency (PCE) of P3HT:TiO2 solar cell, we have further increased the crystallinity of anatase TiO2 nanorods. Two novel approaches: (1) ripening and (2) bismuth/boron doping for TiO2 nanorods were explored. The crystallinity of the as-synthesized TiO2 nanorods was increased through ripening (120℃, 24 hrs) by using an autoclave reactor while the size of nanocrystal was not significantly changed. The bismuth doped TiO2 (Bi-doped TiO2) and boron doped TiO2 nanorods (B-doped TiO2) were synthesized using the same sol-gel process of as synthesized TiO2 nanorods. The PCE of P3HT:TiO2 solar cells was increased by 1.31 times and 1.79 times under A. M. 1.5 illumination for ripened and B-doped TiO2, respectively, as compared with as-synthesized TiO2. The B-doped TiO2 has the highest mobility and PCE, mainly due to the presence of partially reduced Ti4+ by boron atom with delocalized electrons. W4-dye is a promising way for modifying the interface between P3HT and TiO2 charge transport further. The Bi-doped TiO2 has higher Jsc as compared with B-doped TiO2, mainly due to the presence of improvement of electron density under TiO2. The PCE of solar cell made of W4-dye modified TiO2 nanorods has been increased by 1.33 times and 1.30 times for Bi-doped TiO2 and B-doped TiO2, respectively, as compared with that of as-synthesized TiO2.
BaQais, Amal. "Development of bismuth (oxy)sulfide-based materials for photocatalytic applications". Diss., 2019. http://hdl.handle.net/10754/630871.
Texto completoWang, Dan y 王丹. "Doped Bismuth Ferrite-based Perovskite Type Cathode Materials for IT-SOFCs". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/35886765639739263603.
Texto completo國立臺灣大學
材料科學與工程學研究所
104
The effects of nickel, cobalt and manganese doping in bismuth-based ferrite perovskite (Bi0.7Sr0.3FeO3-δ) used as cathode of solid oxide fuel cells have been investigated in this study. The cathode powders were synthesized by EDTA-citric acid method. The phase purity of synthesized perovskites were analyzed by X-ray Diffraction (XRD). The solubility limit of Ni was 3 at%, while Mn can substitute for Fe at least 50 at% in BSF. Electrical conductivity by 2-probe and 4-probe DC methods showed that the 50 mol% doping of Mn on B-site improved the electrical conductivity significantly. The oxygen nonstoichiometry was analyzed by X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) to reveal the deficiency of oxygen and ionic conductivity in the ferrites. The ionic conductivity of BSF was 4.21 x10-3 S.cm-1 at 800 oC. Anode disk of 300 μm thick coated with thin layer (μm layer thickness) of electrolyte by spin-coating method. The polarization resistance and contact resistance of the half-cell with an 8YSZ-N flat layer and cathode sintered by different sintering temperatures were analyzed by electrochemical impedance spectra analysis (EIS). Finally, the optimal cathode (Bi0.7Sr0.3Fe0.5Mn0.5O 2.88-0.034+20 SDC) was assembled to a full cell and the maximum power output was 119 mW.cm-2 at 800 oC.
Lin, Jyun-Min y 林俊名. "Fabrication and characteristics of Bismuth Telluride and Antimony Telluride-based thermoelectric materials". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/k43m27.
Texto completo國立中山大學
電機工程學系研究所
104
The crisis of energy shortage and carbon reduction has become an important issue; the green technology is getting more and more attention. The thermoelectric power generator exhibits the advantages of environmental protection and renewable energy. The thermoelectric devices can convert heat energy to electric energy and vice versa. Bismuth telluride (Bi-Te) and antimony telluride (Sb-Te)-based compounds, which exhibit the highest figure of merit (ZT), are known to be the best thermoelectric materials within the room temperature region and are widely utilized for thermoelectric cooling and generation. In this study, thermoelectric materials were prepared by different processing methods. The characteristics of the obtained thermoelectric materials are investigated. The powder metallurgy method was adopted to fabricate Bi2Te2.7Se0.3 and Bi0.5Sb1.5Te3 thermoelectric materials via the ball milling, cold pressing, and sintering processes. The effects of sintering time and temperature on the thermoelectric properties are investigated and discussed for the Bi2Te2.7Se0.3 and Bi0.5Sb1.5Te3 thermoelectric materials. On the other hand, Bi2Te3 and Sb2Te3-based thin films were prepared by thermal evaporation method on the silicon substrates. The influences of substrate temperature and annealing temperature on the surface morphology, crystal structure and thermoelectric properties of thin films are investigated. Further, the Ag-doped Bi2Te3 and Sb2Te3 thin films are also fabricated by co-evaporation and then annealed. The effects of post annealing on the microstructures and thermoelectric properties of the thin films are evaluated. In the study of bulk thermoelectric materials, the Seebeck coefficient of Bi2Te2.7Se0.3 decreased at first and then increased by the increased sintering temperature. Moreover, the results also showed that the thermal conductivity and electrical resistivity exhibited a reversal trend. When the thermal conductivity was increased by the increased sintering temperature, the electrical resistivity was reduced. The calculated PF of 1.074 mW/mK2 was obtained as the sample was sintered at 723K for 2h. The figure of merit (ZT) of 0.31 was obtained at room temperature as the sample was sintered at 648K for 2h. The thermoelectric properties of Bi0.5Sb1.5Te3 showed that the optimal Seebeck coefficient of 300.694 μV/K was obtained as the sample was sintered at 623K for 1h and the resistivity reached the maximum. The figure of merit (ZT) of 0.15 was obtained at room temperature as the sample was sintered at 648K for 3h, in which, the structure showed the rectangular prism crystallization. Besides, n-type Bi2Te3 and p-type Sb2Te3 thin films were deposited on SiO2/Si substrates using thermal evaporation method in this thesis. The influences of substrate temperature and thermal annealing on the structure, composition, morphology and thermoelectric properties of Bi2Te3 and Sb2Te3 thin films were investigated. As the substrate temperature increased to 150°C, the power factors of n-type Bi2Te3-based and p-type Sb2Te3-based thin films were found to be about 4.89 μW/cm⋅K2 and 3.94 μW/cm⋅K2, respectively. Further, the Ag-doped thin films were fabricated by co-evaporation and the thermal annealing treatment was carried out. The results showed that the Ag-doped Bi2Te3 with a maximized value of power factor of 2.16 μW/cm·K2 could be obtained at the substrate temperature of 100°C and annealing temperature of 250°C (0.5hr). In the Ag-doped Sb2Te3, the thin films exhibited a maximized value of power factor of 19.99 μW/cm·K2 at the substrate temperature of 150°C and annealing temperature of 200°C (0.5hr).
Huang, Te-Jung y 黃德榮. "Bismuth-based perovskite as cathode materials for intermediate -temperature solid oxide fuel cells". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/44353231110258177997.
Texto completo國立臺灣大學
材料科學與工程學研究所
101
Two series perovskites, Bi1-xSrxFeO3-δ (x = 0.1-0.5) and Bi0.5Sr0.5CoyFe1-yO3-δ (y = 0-0.2), have been synthesized by EDTA-citric complexing method and characterized in intermediate-temperature range (600 to 800°C) by X-ray diffraction, electrical property study, thermal analysis and cell testing. The results show single-phase perovskite structure offering CTE values from 10.0 to 19.1 ppmk-1. Two samples S50 and S50C20 perform maximal electrical and ionic conductivities among the series. Polarization resistance from Nyquist plot depicts that S50C20 has a lowest value of 0.10 Ω.cm2. The cells with S50 or S50C20 cathode comparing to the standard cell with La0.6Sr0.4Co0.2Fe0.8O3-δ cathode show the power density 361 mWcm-2,405 mW cm-2 and 353 mW cm-2,respectively. The cells with Bi-base cathodes have a power density higher then that of STD cell.
Tai-KuangLee y 李泰廣. "Studies on Lead-free Piezoelectric Materials and Device based on Bismuth Layer and Perovskite Structure". Thesis, 2016. http://ndltd.ncl.edu.tw/handle/vs7jkk.
Texto completoLAKSHMANAN, GURUSAMY y 古沙力. "A Study of Nanostructured Bismuth and Molybdenum Based Electrode Materials for Energy Storage Supercapacitor Application". Thesis, 2019. http://ndltd.ncl.edu.tw/handle/sh649c.
Texto completo逢甲大學
環境工程與科學學系
107
Abstract Supercapacitors have been relatives of energy storage devices, which is the conversion of the electrical energy from sustainable energy sources of solar, wind energy and so on. They differentiate from another family of energy storage devices like Li, Na and K ion batteries, for instance, batteries are able to full charging take time meanwhile discharging in seconds. The overall supercapacitor performances of developing electrode materials have been relying on the outstanding electrical conductivity, porous nanostructures with excellent long-term stability and larger surface areas. These properties are attractive and extensive research efforts to move on one-step forward to developing the supercapacitor performances. The scope of this dissertation to design and synthesis of bismuth and molybdenum-based electrode materials, with their application of supercapacitor. Bismuth-based electrode materials, the increasing loading amount of RGO nanosheets to improve the electrical conductivity on Bi2O2CO3 electrode materials at three-electrode configuration. In addition, the anode of Bi2O3/porous-RGO nanosheet has been prepared with the help of catalytic carbon gasification method and then combine with cathode materials of α-MnO2 to exhibits high energy/power density at two-electrode configuration. Molybdenum-based electrode materials, the hexagonal-MoO3 nanoplates have been create the high amount of oxygen vacancy concentration in crystal lattice at high annealing temperature and thereby interlayer distance increases and enhance the electrical conductivity. The highest oxygen vacancy concentration of hexagonal-MoO3 nanoplates is generated the crystal defects in the presence of NH4+ ions such as grain and twin boundaries, amorphous and screw dislocation. This crystal defects to produce the diffusion path for electrolyte ions easily move on the electrode surface and thus improve the charge storage performances. Furthermore, the hetero-atoms of nitrogen doped hallow carbon nanotubes are augmented the electrical conductivity of molybdenum oxy-carbide nanoparticles in acidic condition. The above our synthesized bismuth and molybdenum-based nanostructured electrode materials to make new insight for future work of asymmetric supercapacitor fabrication techniques. Keywords: Porous-RGO, Bismuth, Molybdenum, Crystal defects, Electrical conductivity
Garg, Rohini. "Structural, Ferroelectric, Piezoelectric and Phase Transition Studies of Lead Free (Na0.5Bi0.5)TiO3 Based Ceramics". Thesis, 2013. http://etd.iisc.ernet.in/2005/3446.
Texto completoBali, Ashoka. "Study of Thermoelectric Properties of Lead Telluride Based Alloys and Two-Phase Compounds". Thesis, 2014. http://hdl.handle.net/2005/2950.
Texto completoPires, Tatiana Rafaela Lopes. "Comparative analysis of chromatic alterations of a Calcium Silicate-based Material: in vitro study". Master's thesis, 2014. http://hdl.handle.net/10316/36720.
Texto completoObjective: The purpose of this study was to investigate and compare chromatic alterations of an inorganic silicate-based cement, also known as white mineral trioxide aggregate (WMTA), submitted to different environmental conditions using the CIE L*a*b* system evaluated by two different methods. Methods: Twenty-four samples of WMTA (ProRoot® MTA, Dentsply Tulsa Dental, Johnson City, TN) were randomly distributed in four groups (n=4). In group 1 the samples did not undergo any additional treatment (negative control group). In group 2 WMTA samples were light irradiated for 60 seconds using a LED poliwave curing unit. In group 3 and 4 WMTA samples were coated with a layer of glycerine and adhesive, respectively and light irradiated for 60 seconds. A commercial spectrophotometer (VITA Easyshade® Advance 4.0, VidentTM, California, USA) and calibrated photographic digital analysis were used to determine colour coordinates from the CIE L*a*b* system of each sample after three different time points: 30 minutes, 48 hours and 7 days. In order to understand the chemical alterations associated to colour variations of the material x-ray diffraction analysis was also conducted. Data was analysed using statistical software IBM® SPSS® Statistics, version 20. Results: Consistency between the two colour measuring methods was not observed. Significant colour variation was observed for group 3. X-ray diffraction analysis showed no differences between compounds. Conclusion: WMTA showed significant dark discolouration after irradiation with an LED poliwave curing unit in an oxygen-free environment promoted by glycerine although after 48 hours discolouration had faded. The same light irradiation protocol associated to an oxygen-free conditions achieved by an adhesive resin layer did not induce significant discolouration at the end of the experiment protocol.
Devesa, Susana Margarida. "Novos materiais à base de niobato de bismuto para armazenamento de energia elétrica". Doctoral thesis, 2019. http://hdl.handle.net/10773/29145.
Texto completoThe development of new materials, that allow the reduction of size of electronic components, has been in the scope of the researchers. The bismuth-based dielectric ceramics are extensively studied for this propose, in particular the bismuth niobate (BiNbO4). The first attempt to improve the electric properties of BiNbO4 occurred in 1992, with the addition of oxides. This work focus in the improvement of bismuth niobate ceramics using the substitution of bismuth ions by iron and europium ions. To investigate the inclusion of iron and europium in BiNbO4 ceramics, (Bi1-xFex)NbO4 and (Bi1-yEuy)NbO4, samples were prepared using the sol-gel method. Since the substitution of bismuth ions by iron ions was successful, composites of BiNbO4-FeNbO4 were prepared by the solid state reaction method, using as precursors the BiNbO4 and FeNbO4 produced by the sol-gel method. The structure of the prepared samples was studied by X-ray diffraction and Raman spectroscopy and the morphology by scanning electron microscopy. The dielectric properties were studied, in the microwave frequency range, using the resonant cavity method, and in the radio frequency range, with the impedance spectroscopy technique. At the frequency of 100 kHz, the sample with the most promising dielectric properties belongs to the system (Bi1-xFex)NbO4, with x = 0.25, thermally treated at 1100 °C, which has the values of 166, 0.37 and 0.0022 for the dielectric constant, dielectric losses and loss tangent, respectively. At the frequency of 2.7 GHz, it is the sample of BiNbO4, without any substitution, thermally treated at 650 °C, which presents the most advantageous dielectric properties, with values of 5, 0.01 and 0.002 for the dielectric constant, dielectric losses and loss tangent, respectively. Although the values of the dielectric constant are not particularly high, it should be noted that the dielectric losses remain very low.
Programa Doutoral em Engenharia Física