The application and efficiency of optoelectronic devices depends on the ability to control the absorption and emission processes of photons in semiconductors. This thesis looks at three different applications of spectral management across a broad range of optoelectronic devices: photovoltaics (PVs), luminescent solar concentrators (LSCs) and light-emitting diodes (LEDs). Multiple excitation generation (MEG) – a process in which multiple charge-carrier pairs are generated from a single optical excitation - is a promising way to improve the photocurrent in photovoltaic devices and offers the potential to break the Shockley-Queisser limit. Here we present solar cells fabricated from PbSe nanorods which show external quantum efficiencies exceeding 100 %. This demonstrates the potential for substantial improvements in PV device performance due to MEG. Through spatial and spectral concentration, LSCs have the potential to reduce the cost of photovoltaic energy production and are attractive prospects for photobioreactors and building-integrated applications. Here we introduce versatile star-shaped donor-acceptor molecules based on a central BODIPY acceptor with oligofluorene donor side units. We perform comprehensive device measurements and Monte Carlo ray tracing simulations of LSCs. We find that the measured structures permit waveguide propagation lengths on a par with state-of-the-art nanocrystalline emitters, while proposed hypothetical structures can be seen as viable candidates for photobioreactor and energy production roles and should be synthesized. The efficiency of nanocrystal-based LEDs is inherently limited by the types of crystals used. Cesium lead halide perovskite nanocrystals exhibit photoluminescence quantum efficiencies approaching 100%. However, due to the large surface areas and anion mobility halogen exchange between perovskite nanocrystals of different compositions occurs rapidly, limiting applications. Here, we report significantly reduced halide exchange between chloride and iodide CsPbX3 (X= Cl, I) perovskite nanocrystals. We investigate perovskite-based multi-crystal component samples and their resulting optical and electrical interactions in bulk heterojunction LEDs. Efficient photon reabsorption from CsPbCl3 to CsPbI3 nanocrystals was found to improve LED device performance.

Orientador: Paulo Noronha Lisboa Filho / Banca: José Varalda / Banca: José Humberto Dias da Silva / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem caráter institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: As manganitas óxidas apresentam um complexo diagrama de fases magnéticas e muitos dos seus mecanismos fundamentais de interação magnética ainda precisam ser explorados. A nível cristalográfico, as manganitas óxidas de terras-raras têm suas propriedades magnéticas fortemente afetadas pela variação do íon de terra na estrutura cristalina do composto, pela natureza do elemento de transição presente na composição e pela possibilidade deste metal sofrer flutuações de valência. Além disso, a natural ocorrência de vacâncias de oxigênio também presentes nesses materiais cerâmicos são responsáveis por respostas magnéticas distintas. Este trabalho teve como objetivo a síntese, a caracterização estrutural e a caracterização magnética de dois conjuntos de amostras policristalinas da família Er'Co IND. x''Mn IND. 1-x''O IND> 3+ou - δ' preparados pelo Método dos Precursores Poliméricos. O primeiro conjunto apresenta diferentes valores das composições relativas de manganês e cobalto e um segundo conjunto apresenta variações na estequiometria de oxigênio, além dos compostos base ErMn'O POT. 3' e ErCo'O POT. 3'. Para a caracterização cristalográfica, as amostras foram estudadas por difração de Raios X e analisadas através do método de refinamento Rietveld, e a caracterização magnética foi feita por medidas de magnetização em função da temperatura e em função do campo magnético aplicado. Da análise estrutural, tem-se que as amostras produzidas possuíam frações muito pequenas de fases secundárias, sendo que as fases foram quantificadas através do método Rietveld. As medidas magnéticas mostraram a extensa coexistência de diferentes respostas magnéticas para as amostras com composição relativa Co/Mn. / Abstract: Manganese based oxides present a very complex magnetic phase diagram and still have many of their basic physical properties and magnetic interaction to be better explored. At crystallographic level, rare-earth oxide manganites have their magnetic properties strongly effected by tchanges in the rare-earth ion present in the structure, the nature of the transition element in the structure and also by the possibility of electronic valence fluctuations. Furthermore, the occurrence of oxygen vacancies are also responsible for a sort of different magnetic responses. In this work it was studied the synthesis procedure, structural and magnetic characterization of polycrystalline samples of the ErMn'O POT. 3' e ErCo'O POT. 3' family prepared by a polymeric precursors method. A first group of samples presents different manganese and cobalt contents ratio and a second group of the analized samples presents variations in the oxygen stoichiometric. The structural and crystalographic characterization were performed by X ray powder diffraction and further analyzed by the Rietveld refinement method, and the magnetic characteristic were studied by measurements of magnetization as a function of temperature at different values of applied magnetic field. From structural analysis, the produced sample have a small piece of secondary phase, that were quantifity using the Rietveld method. The magnetic measures showed a larger coexistence of differents magnetics interactions to sample with relative composition Co/Mn. / Mestre

Este trabalho investigou o sistema (1 - x )PZT - x PMN, avaliando a influência da composição química e dos parâmetros de sinterização na microestrutura e propriedades elétricas dos corpos cerâmicos obtidos pelo método convencional de mistura de óxidos. Os óxidos usados foram o Nb2O5, ZrO2, TiO2, PbO e MgCO3, cominuídos e homogeneizados em moinho de bolas, por 3 horas. Para o 0,65PZT - 0,35PMN, utilizou-se 28,58% de Nb2O5, 38,93% de ZrO2, 23,29% de TiO2 e 9,2% de MgCO3; para o 0,75PZT-0,25PMN, utilizou-se 20,9% de Nb2O5, 45,34% de ZrO2, 27,13% de TiO2 e 6,62% de MgCO3 e para o 0,85PZT-0,15PMN, usa-se 12,71% de Nb2O5, 52,09% de ZrO2, 31,16% de TiO2 e 4,04% de MgCO3. O pó obtido foi submetido a calcinação a 1200°C por 4 h e, então, acrescentado PbO com um excesso de 2% em massa.à mistura, a qual foi submetida a uma nova calcinação a 800°C durante 2 horas. O pó resultante da calcinação foi conformado por prensagem, utilizando uma prensa uniaxial a 190 MPa, na forma de discos medindo 10 mm de diâmetro e 1,5 mm de espessura. A curva de queima dos corpos cerâmicos consistiu em um novo patamar a 500°C por 4h (e/ou a 800°C por 2h) e outro consecutivo a 1200°C por 4h. As amostras foram caracterizadas pela sua densidade e porosidade aparente (método de Arquimedes), composição de fases (por difração de raio-X), Microscopia Eletrônica de Varredura (MEV) e caracterização elétrica (constante dielétrica e capacitância). Os corpos cerâmicos correspondentes à composição 0,75PZT-0,25PMN alcançaram a maior densidade (7,09 ± 0,18 g/cm³) quando calcinados sucessivamente a 500°C e a 800°C, com os maiores valores de capacitância (210 pF a 200 KHz) e de constante dielétrica (1000 na frequência de 1 KHz), com menor evidência de formação de pirocloro e maior de perovskita. Os valores de constante dielétrica encontrados estão dentro do esperado para materiais cerâmicos piezoelétricos do tipo PZT - PMN, aproximadamente 1000 para freqüências de 1KHz. / This work investigated the system (1 - x )PZT - x PMN, evaluating the influence of the chemical composition and the sintering parameters on the microstructure and the electric properties of ceramic bodies obtained by the conventional method of mixture of oxides. The used oxides were Nb2O5, ZrO2, TiO2, PbO e MgCO3, squeezed and homogenized in mill of balls, for 3 hours. For the 0.65PZT-0.35PMN, it was used 28.58% of Nb2O5, 38.93% of ZrO2, 23.29% of TiO2 and 9.2% of MgCO3; for the 0.75PZT-0.25PMN, it was used 20.9% of Nb2O5, 45.34% of ZrO2, 27.13% of TiO2 and 6.62% of MgCO3 and for the 0.85PZT-0.15PMN, it is used 12.71% of Nb2O5, 52.09% of ZrO2, 31.16% of TiO2 and 4.04% of MgCO3. The obtained powder was submitted the calcination for 1200°C for 4 h and, then, increased PbO with an excess of 2% in mass, which was submitted to a new calcination to 800°C for 2 hours. The calcinated powder was conformed by pressing, using a uniaxial press to 190 MPa, in the form of disks measuring a diameter of 10mm and 1.5 mm of thickness. The curve of the burning of the ceramic bodies consisted in a new calcination to 500°C for 4h (and/or to 800°C for 2h) and other consecutive to 1200°C for 4h. The samples were characterized by density and apparent porosity (Method of Arquimedes), composition of phases (by X - rays diffraction), Scanning Electric Microstructure (SEM) and electrical properties characterization (dielectric constant and capacitance). The ceramic bodies corresponding to the composition 0.75PZT-0.25PMN reached the largest density (7.09 ± 0.18 g/cm³) when calcined successively to 500°C and 800°C, with the largest values of capacitance (210 pF to 200 KHz) and dielectric constant (1000 in the frequency of 1 KHz), with smaller evidence of pyrochlore formation and larger of perovskte. The values of dielectric constant found are inside of the expected for the piezoelectric ceramics of the type PZT- PMN, approximately 1000 by frequencies of 1KHz.

Light reflection from the glass surface of a photovoltaic (PV) module is a significant source of energy loss for all types of PV devices. The reflection at the glass and air interface accounts for ~4% of the total energy. Single layer anti-reflection coatings with sufficiently low refractive index have been used, such as those using magnesium fluoride or porous silica, but these are only effective over a narrow range of wavelengths. Multilayer-antireflection coatings reduce the weighted average reflection over the wavelength range used by solar technologies more effectively by utilising interference effects. Multilayer stacks consisting of silica and zirconia layers deposited using reactive magnetron sputtering and single layer porous silica coatings were compared in terms of effectiveness and durability. Details of the stack design, sputter deposition process parameters, and the optical and micro-structural properties of the layers of the multilayer coating are provided and similar properties where applicable for the single layer coatings. Anti-reflection coatings on glass exposed to the outdoors must not degrade over the lifetime of the module. A comprehensive set of accelerated environmental durability tests has been carried out in accordance with IEC 61646 PV qualification tests. The durability tests confirmed no damage to the coatings or performance drop as a result of thermal cycling or damp heat. All attempts to perform pull tests on either coating resulted in either adhesive or substrate failure, with no damage to the coating itself. Scratch resistance, abrasion resistance, and adhesion tests have also been conducted. The optical performance of the coatings was monitored during these tests and the coatings were visually inspected for any sign of mechanical failure. These tests provide confidence that broadband anti-reflection coatings are highly durable and will maintain their performance over the lifetime of the solar module. Additionally heat treatment experiments demonstrated both coatings can withstand up to 600°C temperatures and can thereby withstand CdTe manufacturing processes allowing for pre-coated glass. Additionally experiments demonstrated that multi-layer coatings are resistant to acid attack. Thin film photovoltaic devices are multilayer opto-electrical structures in which light interference occurs. Light reflection at the interfaces and absorption within the window layers reduces transmission and, ultimately, the conversion efficiency of photovoltaic devices. Optical reflection losses can be reduced by adjusting the layer thicknesses to achieve destructive interference within the structure of the cell. The light transmission to the CdTe absorber of a CdS/CdTe cell on a fluorine doped tin oxide transparent conductor has been modelled using the transfer matrix method. The interference effect in the CdS layer and high resistance transparent buffer layers (SnO2 and ZnO) has been investigated. The modelling shows that due to relatively high absorption within the SnO2 layer, there are modest benefits to engineering anti-reflection interference in the stack. However, a ZnO buffer layer has limited absorption and interference can be exploited to provide useful anti-reflection effects. Additionally the light transmission to the perovskite absorber of a thin film solar cell using fluorine doped tin oxide (FTO) transparent conductor has been modelled. Alternative transparent conductor materials have also been investigated including aluminium doped zinc oxide (AZO) and indium tin oxide (ITO) and shown to be beneficial to transmission.

Over the last five years hybrid organic-inorganic metal halide perovskites have attracted strong interest in the solar cell community as a result of their high power conversion efficiency and the solid opportunity to realise a low-cost as well as industry-scalable technology. Nevertheless, several aspects of this novel class of materials still need to be explored and the level of our understanding is rapidly and constantly evolving, from month to month. This dissertation reports investigations of perovskite solar cells with a particular focus on their local chemical composition. The analytical characterisation of such devices is very challenging due to the intrinsic instability of the organic component in the nanostructured compounds building up the cell. STEM-EDX (Scanning Transmission Electron Microscopy - Energy Dispersive X-ray spectroscopy) was employed to resolve at the nanoscale the morphology and the elemental composition of the devices. Firstly, a powerful procedure, involving FIB (Focus Ion Beam) sample preparation, the acquisition of STEM-EDX maps and the application of cutting edge post-processing data techniques based on multivariate analysis was developed and tested. The application of this method has drastically improved the quality of the signal that can be extracted from perovskite thin films before the onset of beam-induced transformations. Morphology, composition and interfaces in devices deposited by using different methodologies and external conditions were then explored in detail by combining multiple complementary advanced characterisation tools. The observed variations in the nanostructure of the cells were related to different photovoltaic performance, providing instructive indications for the synthesis and fabrication routes of the devices. Finally, the main degradation processes that affect perovskite solar cells were probed. STEM-EDX was used in conjunction with the application of in situ heating, leading to the direct observation of elemental species migration within the device, reported here for the first time with nanometric spatial resolution. Further analyses, involving a set of experiments aimed to study the effects of air exposure and light soaking on the cells, were designed and performed, providing evidence of the main pathways leading to the drastic drop in the device performance.

Este trabalho investigou o sistema (1 - x )PZT - x PMN, avaliando a influência da composição química e dos parâmetros de sinterização na microestrutura e propriedades elétricas dos corpos cerâmicos obtidos pelo método convencional de mistura de óxidos. Os óxidos usados foram o Nb2O5, ZrO2, TiO2, PbO e MgCO3, cominuídos e homogeneizados em moinho de bolas, por 3 horas. Para o 0,65PZT - 0,35PMN, utilizou-se 28,58% de Nb2O5, 38,93% de ZrO2, 23,29% de TiO2 e 9,2% de MgCO3; para o 0,75PZT-0,25PMN, utilizou-se 20,9% de Nb2O5, 45,34% de ZrO2, 27,13% de TiO2 e 6,62% de MgCO3 e para o 0,85PZT-0,15PMN, usa-se 12,71% de Nb2O5, 52,09% de ZrO2, 31,16% de TiO2 e 4,04% de MgCO3. O pó obtido foi submetido a calcinação a 1200°C por 4 h e, então, acrescentado PbO com um excesso de 2% em massa.à mistura, a qual foi submetida a uma nova calcinação a 800°C durante 2 horas. O pó resultante da calcinação foi conformado por prensagem, utilizando uma prensa uniaxial a 190 MPa, na forma de discos medindo 10 mm de diâmetro e 1,5 mm de espessura. A curva de queima dos corpos cerâmicos consistiu em um novo patamar a 500°C por 4h (e/ou a 800°C por 2h) e outro consecutivo a 1200°C por 4h. As amostras foram caracterizadas pela sua densidade e porosidade aparente (método de Arquimedes), composição de fases (por difração de raio-X), Microscopia Eletrônica de Varredura (MEV) e caracterização elétrica (constante dielétrica e capacitância). Os corpos cerâmicos correspondentes à composição 0,75PZT-0,25PMN alcançaram a maior densidade (7,09 ± 0,18 g/cm³) quando calcinados sucessivamente a 500°C e a 800°C, com os maiores valores de capacitância (210 pF a 200 KHz) e de constante dielétrica (1000 na frequência de 1 KHz), com menor evidência de formação de pirocloro e maior de perovskita. Os valores de constante dielétrica encontrados estão dentro do esperado para materiais cerâmicos piezoelétricos do tipo PZT - PMN, aproximadamente 1000 para freqüências de 1KHz. / This work investigated the system (1 - x )PZT - x PMN, evaluating the influence of the chemical composition and the sintering parameters on the microstructure and the electric properties of ceramic bodies obtained by the conventional method of mixture of oxides. The used oxides were Nb2O5, ZrO2, TiO2, PbO e MgCO3, squeezed and homogenized in mill of balls, for 3 hours. For the 0.65PZT-0.35PMN, it was used 28.58% of Nb2O5, 38.93% of ZrO2, 23.29% of TiO2 and 9.2% of MgCO3; for the 0.75PZT-0.25PMN, it was used 20.9% of Nb2O5, 45.34% of ZrO2, 27.13% of TiO2 and 6.62% of MgCO3 and for the 0.85PZT-0.15PMN, it is used 12.71% of Nb2O5, 52.09% of ZrO2, 31.16% of TiO2 and 4.04% of MgCO3. The obtained powder was submitted the calcination for 1200°C for 4 h and, then, increased PbO with an excess of 2% in mass, which was submitted to a new calcination to 800°C for 2 hours. The calcinated powder was conformed by pressing, using a uniaxial press to 190 MPa, in the form of disks measuring a diameter of 10mm and 1.5 mm of thickness. The curve of the burning of the ceramic bodies consisted in a new calcination to 500°C for 4h (and/or to 800°C for 2h) and other consecutive to 1200°C for 4h. The samples were characterized by density and apparent porosity (Method of Arquimedes), composition of phases (by X - rays diffraction), Scanning Electric Microstructure (SEM) and electrical properties characterization (dielectric constant and capacitance). The ceramic bodies corresponding to the composition 0.75PZT-0.25PMN reached the largest density (7.09 ± 0.18 g/cm³) when calcined successively to 500°C and 800°C, with the largest values of capacitance (210 pF to 200 KHz) and dielectric constant (1000 in the frequency of 1 KHz), with smaller evidence of pyrochlore formation and larger of perovskte. The values of dielectric constant found are inside of the expected for the piezoelectric ceramics of the type PZT- PMN, approximately 1000 by frequencies of 1KHz.

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O mundo moderno é extremamente dependente de combustíveis fósseis como fonte de energia primária e essa forte dependência leva a problemas políticos, econômicos e ambientais. Como possível solução a esses problemas tem-se as células combustíveis, pois são dispositivos que geram energia elétrica limpa diretamente de reações eletroquímicas produzindo, além da energia elétrica, apenas calor e água. Logo, percebe-se que essas células são fontes de energia confiáveis, renováveis e não poluentes, que contribuem para o desenvolvimento sustentável. Devido a isso, este trabalho teve como objetivo principal a síntese (por um método inédito) e a caracterização de materiais porosos a base de cromita de lantânio, LaxSr1-xCryFe1-y(Mn1-y)O3-?, para possível implementação como material de anodo e catodo de célula a combustível de óxido sólido (SOFC). Particularmente, estudos com anodos nos quais o transporte eletrônico é feito por materiais cerâmicos ao invés de metais são a área mais promissora na pesquisa recente. Além disso, materiais a base de manganita de lantânio dopadas com estrôncio são na atualidade os materiais mais usados na construção do catodo da SOFC. Nesta tese os materiais foram sintetizados pelo método sol-gel com agentes direcionador e dilatador de estrutura, resultando em materiais porosos em forma de esponja e com a estrutura perovskita, porém com fases espúrias. Foi estudada a influência do processamento de calcinação e de dopagem sobre as estruturas cristalográficas e porosas dos materiais. A maior temperatura de calcinação favoreceu a formação da estrutura perovskita com a retenção da fase romboédrica e reduziu a presença das fases espúrias, porém reduziu a porosidade, principalmente dos menores mesoporos, e a área superficial dos materiais. Por outro lado, ao dopar o sítio B os materiais com 75 %mol de La e calcinação a 1000 °C, observou-se a formação de um maior volume de mesoporos, ao mesmo tempo, que produziu uma maior quantidade de mesoporos menores e favoreceu a retenção da fase romboédrica da estrutura perovskita. Quanto ao comportamento eletrocatalítico, as células com eletrodos confeccionados a partir de La0,33Sr0,66Cr0,33Mn0,33O3-? apresentaram os melhores resultados tanto para anodo como para catodo entre as amostras avaliadas na tese. Além do mais, foram obtidos dois materiais, um cerâmico (La0,33Sr0,66Cr0,33Mn0,33O3-?) e um compósito cerâmico (La0,33Sr0,66Cr0,33Mn0,33O3-? + ZrO2 8%mol Y2O3) bons candidatos a catodo da SOFC. Esses materiais possuem uma composição química não encontrada na literatura para tal finalidade, ou seja, são inéditos. / The modern world is extremely dependent on fossil combustibles as primary source of energy and, this dependence brings political, economic and ambient problems. As a possible solution to these problems are the fuel cells, because they are devices that generate clean electric energy directly from electrochemical reactions, producing besides electric energy, heat and water. Therefore, these cells are reliable, renewable and non-pollutant sources, that contribute to the sustainable development. Related to it, this work had the main goal the synthesis (by a new method) and characterization of porous materials based on lanthanum chromite, LaxSr1-xCryFe1-y(Mn1-y)O3-?, for possible use as anode and cathode material of Solid Oxide Fuel Cell (SOFC). In particular, studies of anodes in which the electronic transport is performed by ceramic materials instead of metals are the most promising recent research area. Moreover, materials based on lanthanum manganite doped with strontium are now a days the more used materials for SOFC cathodes. In this thesis, the materials were synthesized by the sol-gel method with directing and swelling structure agents, resulting in porous sponge materials with perovskite structure, but having spurious phases. The influence of the calcination and doping of the materials upon the crystallographic and porous structures were studied. Higher calcination temperature favored the formation of the perovskite structure and reduced the presence of spurious phases, but reduced the porosity, mainly of smaller mesopores and the surface area. On the other hand, doping the B site in materials with 75 %mol of La and the calcination at 1000 oC produced a higher mesopore volume, a higher amount of small mesopores and favored the retention of the rhombohedral perovskite structure. Regarding the catalytic behavior, the cells with electrodes of La0,33Sr0,66Cr0,33Mn0,33O3-? presented the best results as anode and cathode among the evaluate samples. Moreover, two materials were obtained, a ceramic one, (La0,33Sr0,66Cr0,33Mn0,33O3-?) and a ceramic composite, (La0,33Sr0,66Cr0,33Mn0,33O3-? + ZrO2 8%mol Y2O3), good candidates as SOFC cathodes. These materials have a chemical composition, which were not reported in the literature for this application, being unique.

Este trabalho investigou o sistema (1 - x )PZT - x PMN, avaliando a influência da composição química e dos parâmetros de sinterização na microestrutura e propriedades elétricas dos corpos cerâmicos obtidos pelo método convencional de mistura de óxidos. Os óxidos usados foram o Nb2O5, ZrO2, TiO2, PbO e MgCO3, cominuídos e homogeneizados em moinho de bolas, por 3 horas. Para o 0,65PZT - 0,35PMN, utilizou-se 28,58% de Nb2O5, 38,93% de ZrO2, 23,29% de TiO2 e 9,2% de MgCO3; para o 0,75PZT-0,25PMN, utilizou-se 20,9% de Nb2O5, 45,34% de ZrO2, 27,13% de TiO2 e 6,62% de MgCO3 e para o 0,85PZT-0,15PMN, usa-se 12,71% de Nb2O5, 52,09% de ZrO2, 31,16% de TiO2 e 4,04% de MgCO3. O pó obtido foi submetido a calcinação a 1200°C por 4 h e, então, acrescentado PbO com um excesso de 2% em massa.à mistura, a qual foi submetida a uma nova calcinação a 800°C durante 2 horas. O pó resultante da calcinação foi conformado por prensagem, utilizando uma prensa uniaxial a 190 MPa, na forma de discos medindo 10 mm de diâmetro e 1,5 mm de espessura. A curva de queima dos corpos cerâmicos consistiu em um novo patamar a 500°C por 4h (e/ou a 800°C por 2h) e outro consecutivo a 1200°C por 4h. As amostras foram caracterizadas pela sua densidade e porosidade aparente (método de Arquimedes), composição de fases (por difração de raio-X), Microscopia Eletrônica de Varredura (MEV) e caracterização elétrica (constante dielétrica e capacitância). Os corpos cerâmicos correspondentes à composição 0,75PZT-0,25PMN alcançaram a maior densidade (7,09 ± 0,18 g/cm³) quando calcinados sucessivamente a 500°C e a 800°C, com os maiores valores de capacitância (210 pF a 200 KHz) e de constante dielétrica (1000 na frequência de 1 KHz), com menor evidência de formação de pirocloro e maior de perovskita. Os valores de constante dielétrica encontrados estão dentro do esperado para materiais cerâmicos piezoelétricos do tipo PZT - PMN, aproximadamente 1000 para freqüências de 1KHz. / This work investigated the system (1 - x )PZT - x PMN, evaluating the influence of the chemical composition and the sintering parameters on the microstructure and the electric properties of ceramic bodies obtained by the conventional method of mixture of oxides. The used oxides were Nb2O5, ZrO2, TiO2, PbO e MgCO3, squeezed and homogenized in mill of balls, for 3 hours. For the 0.65PZT-0.35PMN, it was used 28.58% of Nb2O5, 38.93% of ZrO2, 23.29% of TiO2 and 9.2% of MgCO3; for the 0.75PZT-0.25PMN, it was used 20.9% of Nb2O5, 45.34% of ZrO2, 27.13% of TiO2 and 6.62% of MgCO3 and for the 0.85PZT-0.15PMN, it is used 12.71% of Nb2O5, 52.09% of ZrO2, 31.16% of TiO2 and 4.04% of MgCO3. The obtained powder was submitted the calcination for 1200°C for 4 h and, then, increased PbO with an excess of 2% in mass, which was submitted to a new calcination to 800°C for 2 hours. The calcinated powder was conformed by pressing, using a uniaxial press to 190 MPa, in the form of disks measuring a diameter of 10mm and 1.5 mm of thickness. The curve of the burning of the ceramic bodies consisted in a new calcination to 500°C for 4h (and/or to 800°C for 2h) and other consecutive to 1200°C for 4h. The samples were characterized by density and apparent porosity (Method of Arquimedes), composition of phases (by X - rays diffraction), Scanning Electric Microstructure (SEM) and electrical properties characterization (dielectric constant and capacitance). The ceramic bodies corresponding to the composition 0.75PZT-0.25PMN reached the largest density (7.09 ± 0.18 g/cm³) when calcined successively to 500°C and 800°C, with the largest values of capacitance (210 pF to 200 KHz) and dielectric constant (1000 in the frequency of 1 KHz), with smaller evidence of pyrochlore formation and larger of perovskte. The values of dielectric constant found are inside of the expected for the piezoelectric ceramics of the type PZT- PMN, approximately 1000 by frequencies of 1KHz.

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