Among the myraid energy storage technologies, polymer electrolytes have been widely employed in diverse applications such as fuel cell membranes, battery separators, mechanical actuators, reverse-osmosis membranes and solar cells. The polymer electrolytes used for these applications usually require a combination of properties, including anisotropic orientation, tunable modulus, high ionic conductivity, light weight, high thermal stability and low cost. These critical properties have motivated researchers to find next-generation polymer electrolytes, for example ion gels. This dissertation aims to develop and characterize a new class of ion gel electrolytes based on ionic liquids and a rigid-rod polyelectrolyte. The rigid-rod polyelectrolyte poly (2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT) is a water-miscible system and forms a liquid crystal phase above a critical concentration. The diverse properties and broad applications of this rigid-rod polyelectrolyte may originate from the double helical conformation of PBDT molecular chains. We primarily develop an ionic liquid-based polymer gel electrolyte that possesses the following exceptional combination of properties: transport anisotropy up to 3.5×, high ionic conductivity (up to 8 mS cm⁻¹), widely tunable modulus (0.03 – 3 GPa) and high thermal stability (up to 300°C). This unique platform that combines ionic liquid and polyelectrolyte is essential to develop more advanced materials for broader applications. After we obtain the ion gels, we then mainly focus on modifying and then applying them in Li-metal batteries. As a next generation of Li batteries, the Li-metal battery offers higher energy capacity compared to the current Li-ion battery, thus satisfying our requirements in developing longer-lasting batteries for portable devices and even electric vehicles. However, Li dendrite growth on the Li metal anode has limited the pratical application of Li-metal batteries. This unexpected Li dendrite growth can be suppressed by developing polymer separators with high modulus (~ Gpa), while maintaining enough ionic conductivity (~ 1 mS/cm). Here, we describe an advanced solid-state electrolyte based on a sulfonated aramid rigid-rod polymer, an ionic liquid (IL), and a lithium salt, showing promise to make a breakthrough. This unique fabrication platform can be a milestone in discovering next-generation electrolyte materials. / Ph. D.

No description available.

Crystalline polymer/salt complexes can conduct, in contrast to the view held for 30 years. The alpha-phase of the crystalline poly(ethylene oxide)₆:LiPF₆ is composed of tunnels formed from pairs of (CH₂-CH₂-O)ₓ chains, within which the Li⁺ ions reside and along which the latter migrate.¹ When a polydispersed polymer is used, the tunnels are composed of 2 strands, each built from a string of PEO chains of varying length. It has been suggested that the number and the arrangement of the chain ends within the tunnels affects the ionic conductivity.² Using polymers with uniform chain length is important if we are to understand the conduction mechanism since monodispersity results in the chain ends occurring at regular distances along the tunnels and imposes a coincidence of the chain ends between the two strands.² Since each Li⁺ is coordinated by 6 ether oxygens (3 oxygens from each of the two polymeric strands forming a tunnel), monodispersed PEOs with the number of ether oxygen being a multiple of 3 (NO = 3n) can form either “all-ideal” or “all-broken” coordination environments at the end of each tunnel, while for both NO = 3n-1 and NO = 3n+1 complexes, both “ideal” and “broken” coordinations must occur throughout the structure. A synthetic procedure has been developed and a series of 6 consecutive (increment of EO unit) monodispersed molecular weight PEOs have been synthesised. The synthesis involves one end protection of a high purity glycol, functionalisation of the other end, ether coupling reaction (Williamson's type ether synthesis³), deprotection and reiteration of ether coupling. The parameters of the process and purification methods have been strictly controlled to ensure unprecedented level of monodispersity for all synthesised samples. Thus obtained high purity polymers have been used to study the influence of the individual chain length on the structure and conductivity of the crystalline complexes with LiPF₆. The results support the previously suggested model of the chain-ends arrangement in the crystalline complexes prepared with monodispersed PEO² over a range of consecutive chain lengths. The synthesised complexes constitute a series of test samples for establishing detailed mechanism of ionic conductivity. Such series of monodispersed crystalline complexes have been studied and characterised here (PXRD, DSC, AC impedance) for the first time. References: 1. G. S. MacGlashan, Y. G. Andreev, P. G. Bruce, Structure of the polymer electrolyte poly(ethylene oxide)₆:LiAsF₆. Nature, 1999, 398(6730): p. 792-794. 2. E. Staunton, Y. G. Andreev, P. G. Bruce, Factors influencing the conductivity of crystalline polymer electrolytes. Faraday Discussions, 2007, 134: p. 143-156. 3. A. Williamson, Theory of Aetherification. Philosophical Magazine, 1850, 37: p. 350-356.

Solid state lithium ion electrolytes are important to the development of next generation safer and high power density lithium ion batteries. Perovskite-structured LLT is a promising solid electrolyte with high lithium ion conductivity. LLT also serves as a good model system to understand lithium ion diffusion behaviors in solids. In this thesis, molecular dynamics and related atomistic computer simulations were used to study the diffusion behavior and diffusion mechanism in bulk crystal and grain boundary in lithium lanthanum titanate (LLT) solid state electrolytes. The effects of defect concentration on the structure and lithium ion diffusion behaviors in LLT were systematically studied and the lithium ion self-diffusion and diffusion energy barrier were investigated by both dynamic simulations and static calculations using the nudged elastic band (NEB) method. The simulation results show that there exist an optimal vacancy concentration at around x=0.067 at which lithium ions have the highest diffusion coefficient and the lowest diffusion energy barrier. The lowest energy barrier from dynamics simulations was found to be around 0.22 eV, which compared favorably with 0.19 eV from static NEB calculations. It was also found that lithium ions diffuse through bottleneck structures made of oxygen ions, which expand in dimension by 8-10% when lithium ions pass through. By designing perovskite structures with large bottleneck sizes can lead to materials with higher lithium ion conductivities. The structure and diffusion behavior of lithium silicate glasses and their interfaces, due to their importance as a grain boundary phase, with LLT crystals were also investigated by using molecular dynamics simulations. The short and medium range structures of the lithium silicate glasses were characterized and the ceramic/glass interface models were obtained using MD simulations. Lithium ion diffusion behaviors in the glass and across the glass/ceramic interfaces were investigated. It was found that there existed a minor segregation of lithium ions at the glass/crystal interface. Lithium ion diffusion energy barrier at the interface was found to be dominated by the glass phase.

The swelling properties of Bentonite are highly affected by clay content and the clay-water interactions that arise from the ion distribution in the diffuse double layer formed near the charged montmorillonite (or smectite) surfaces. Existing continuum models describing the electric double layers, such as classical Poisson-Boltzmann and DLVO theory, ignore the ion-ion correlations, which are especially important for multivalent ions at high surface charge and ionic strength. To better understand the clay-water interactions, atomistic models were developed using both density functional theory of fluids (DFT) as well as classical molecular dynamics (MD) methods. In order to increase our understanding of water-saturated, swelling smectite clays, a DFT, technique was initially developed that allowed more accurate predictions of important thermodynamic properties of the diffuse double layers. This DFT approach was then extended to handle systems with mixtures of different sizes and charges. The extended DFT model was verified against experiments and Monte-Carlo simulations. One practical application was to predict the ion exchange equilibria in Bentonite clays, which have wide practical usage in different areas. Nevertheless, in the DFT work it was realized that DFT demands that the particles, ions in this case, which are described as hard spheres, realistically cannot be described as such at low water loadings, when ion specific hydration forces govern the electric double layer properties. To study how the deformation of the hydration shells of Ca2+ influences the properties of compacted smectite clays, MD simulations using the CLAYFF forcefield were employed in order to account for the deformation of the hydration shells. Comparisons of DFT and MD modeling then allowed to demonstrate under which conditions DFT modeling becomes increasingly inaccurate and when it still can give accurate results. / Under senare år har mycket forskning ägnats åt att förstå egenskaperna hos svällande leror som används för att skydda mot läckage av föroreningar från kontaminerade områden och från framtida slutförvar av radionuklider. Den fria svällningen förorsakas av de starka osmotiska krafter som uppstår när vatten tränger in mellan de tunna elektriskt negativt laddade lermineralskikten och löser de laddningskompenserande jonerna i det diffusa dubbelskiktet. I flera arbeten användandes av sk. kontinuum-teori har vattenmolekylens form, specifika orientering och bindning till katjonerna i de nanometerstora utrymmen mellan lerpartiklarna ej beaktats samt ej heller hur de hydratiserade jonerna orienteras på de atomärt ojämna ytorna. Detta möjliggörs dock genom modellering av de enskilda atomernas och jonernas interaktioner med molekyldynamik simuleringar, MD. I detta arbete har programmet Gromacs använts tillsammans med kraftfältet CLAYFF för att studera dessa fenomen i montmorillonitleror med natrium- och kalciumjoner. Simuleringarna visar att natrium bildar transienta innersfärkomplex vilka orienterar sig i bi-triangulära fördjupningar på ytan, ungefär 3.8 Å från mitt-planet mellan lerytorna. Denna orientering observeras ända upp till att avståndet mellan ytorna ökat till större än motsvarande fem lager vattenmolekyler mellan lerpartiklarnas ytor. Detta sker inte med kalcium, oberoende av avståndet mellan ytorna. Natriumjoner koordineras med fyra vattenmolekyler och en syreatom på leran vid ett lager vatten mellan ytorna och med fem till sex vattenmolekyler, ortogonalt orienterade med ökande mängd vatten mellan ytorna, och med en hydratiserad jon-radie av 3.1 Å. Kalcium koordinerar till sju vattenmolekyler vid ett vattenlager mellan ytorna, men ökar till åtta ortogonalt orienterade vattenmolekyler med en jonradie på 3.3 Å vid större avstånd. Generellt visas att när avståndet mellan lerytorna är mindre än ca 10 Å, deformeras de annars symmetriskt hydratiserade jonerna. En jämförelse mellan MD simuleringar och med klassisk täthetsfunktionalteori, DFT, visar att den senare inte kan beskriva hur yttersfärkomplexen samverkar med laddningarna bundna närmast ytan, dvs i Stern-lagret. / <p>QC 20170403</p>

Pós nanocristalinos de zircônia estabilizada com ítria ou escândia (YSZ ou ScSZ) entre 8 e 12 mol% foram sintetizados por meio dos métodos da poliacrilamida, dos precursores poliméricos e da precipitação simultânea de cátions. Os pós de partida foram analisados por difração de raios X (DRX), distribuição de tamanho de partículas por espalhamento laser, adsorção gasosa (BET), microscopia eletrônica de varredura (MEV), microscopia eletrônica de transmissão (MET), análise térmica simultânea, fluorescência de raios X (FRX), e espectroscopia de absorção óptica no infravermelho por refletância difusa (DRIFT). Os métodos de síntese por via úmida orgânica produziram pós nanocristalinos a partir de 550 °C, enquanto que o método da precipitação simultânea de cátions produziu pós amorfos que cristalizaram em torno de 450 °C com entalpias de cristalização -13,7 ± 0,6 kJ.mol-1 para 8YSZ e -11,7 ± 0,5 kJ.mol-1 para 12YSZ. Os valores de área de superfície específica obtidos para os pós sintetizados por meio dos métodos da poliacrilamida, dos precursores poliméricos e da precipitação (calcinados em ~ 650 °C) foram 27, 61 e 110 m2.g-1, respectivamente. Os pós obtidos pelo método da poliacrilamida apresentaram menor estado de aglomeração e maior quantidade de carbonato superficial relativamente ao pó obtido pelo método dos precursores poliméricos. A sinterização dos compactos de pós cerâmicos foi avaliada por meio da técnica de espectroscopia de impedância (EI) e dilatometria. Após sinterização, as cerâmicas foram analisadas por DRX, MEV e EI. Os resultados evidenciaram que os pós apresentaram elevada sinterabilidade, mas baixa densidade final por causa do estado de aglomeração dos pós. A adsorção de água à temperatura ambiente foi medida em um microcalorímetro Setaram Calvet e um sistema de dosagem Micromeritics. Foram feitos experimentos de calorimetria de solução por inserção de amostra em um calorímetro duplo tipo Calvet usando 3Na2O.4MoO3 como solvente. Estes experimentos, combinados com os de calorimetria de adsorção de água, permitiram determinar por meio de um ciclo termodinâmico, as entalpias de superfície para superfícies hidratadas e anidras. / Nanocrystalline yttria or scandia stabilized zirconia (YSZ, ScSZ) powders with fluorite-type structure were synthesized by the polyacrylamide, the polymeric precursor and the precipitation methods. Powders were characterized by X-ray diffraction (XRD), simultaneous (TG and DTA or DSC) thermal analysis, nitrogen adsorption analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and diffuse reflectance infrared Fourier transform absorption spectroscopy (DRIFT). The organic precursor methods produced nanocrystalline powders at approximately 550 °C and the precipitation method produced amorphous powders which crystallized at approximately 450 °C into a fluorite phase with crystallization enthalpies of -13.7 ± 0.6 kJ.mol-1 for 8YSZ and -11.7 ± 0.5 kJ.mol-1 for 12YSZ. The measured surface area of powders after calcination at 650 - 800 °C were 27 m2.g-1, 61 m2.g-1 and 110 m2.g-1 for the polyacrylamide, the polymeric precursor and the precipitation methods, respectively. The sintering process of the pressed ceramic powders was evaluated by direct impedance spectroscopy (IS) measurements and by dilatometry. Thereafter, the sintered pellets were analyzed by XRD, SEM and IS. The sintering studies show that the powders prepared by the chemical route have high sinterability; however, they do not sinter to high density as a result of dense aggregates in the initial powders. The heats of water adsorption at room temperature were measured on samples using a Setaram Calvet microcalorimeter and a Micromeritics gas dosing system. Drop solution calorimetry experiments were performed in a custom made Calvet twin calorimeter using sodium molybdate 3Na2O.4MoO3 solvent. These experiments, combined with water adsorption calorimetry, allowed for deriving, through a thermodynamic cycle, the surface enthalpies for hydrous and anhydrous surfaces.

Esta tese apresenta os resultados do estudo de eletrólitos poliméricos protônicos obtidos a base de gelatina e quitosana, modificadas através da adição de glicerol e formaldeído - ácidos acético ou clorídrico foram adicionados para promover a condutividade iônica dos filmes. Foram também preparadas blendas a partir de gelatina com quitosana, assim como filmes a base de gelatina e nanopartículas. Com exceção dos filmes com nanopartículas, todos eles possuem boa transparência, estabilidade térmica, maleabilidade, aderência ao vidro e apresentam uma superfície homogênea, sem trincas ou rachaduras. As temperaturas de transição vítrea (Tg) dos eletrólitos foram obtidas do estreitamento de linha de RMN. A taxa de relaxação spin-rede do \'ANTPOT. 1 H\' em função da temperatura mostrou um máximo bem definido cuja posição depende da concentração de ácido no caso da gelatina e da quantidade de glicerol no caso da quitosana, refletindo a alta mobilidade do próton nestes eletrólitos. As técnicas de RPE, onda contínua e pulsada, foram utilizadas para o estudo de eletrólitos dopados com \'CU\'CL\'O IND.4\'. Os valores de condutividade iônica dos eletrólitos são da ordem de \'10 POT.-5\' S/cm para os filmes de gelatina (com ácido acético ou clorídrico), quitosana e blendas e entre \'10 POT.-6\' a \'10 POT.-8\' para os eletrólitos de gelatina com nanopartículas. Estes estudos revelaram que a concentração de ácido acético ou clorídrico (na gelatina), influencia a condutividade iônica dos eletrólitos, mas, para o caso das blendas esta influência é pequena. No caso dos filmes de gelatina com nanopartículas, a condutividade diminui de forma significativa. Em relação aos eletrólitos de quitosana a condutividade iônica é influenciada pela quantidade de glicerol adicionado. Verificou-se que o aumento da temperatura até 80°C promove o aumento da condutividade iônica para todos os filmes estudados. / This thesis shows the results from the study of protonic polymer electrolytes obtained from gelatin and chitosan, modified by the addition of glycerol and formaldehyde - acetic and hydrochloric acids are added to promote the ionic conductivity of the films. Blends based on chitosan and gelatin were also prepared, as well as films based on gelatin and nanoparticles. With the exception of the films with nanoparticles, all samples presented good transparency, thermal stability, flexibility, adhesion to glass and homogeneous surface without cracks. The glass transition temperature (Tg) of the electrolytes were obtained from the NMR line narrowing. The spin-lattice relaxation rate of the \'ANTPOT. 1 H\' spin-network as a function of temperature showed a well-defined maximum whose position depends on the concentration of acid in the case of gelatin and on the glycerol content in the case of chitosan, reflecting the high mobility of the protons in the electrolytes. Continuous wave and pulsed EPR techniques were used to study the electrolytes doped with \'CU\'CL\'O IND.4\'. The values of the ionic conductivity of the electrolytes are of the order of \'10 POT.-5\' S/cm for the films of gelatin (with acetic or hydrochloric acids), chitosan and blends and from \'10 POT.-6\' to \'10 POT.-8\' for the electrolytes of gelatin with nanoparticles. These studies revealed that the concentration of acetic or hydrochloric acids (in gelatin), influences the ionic conductivity of the electrolytes but, in the case of blends, this influence is small. In the case of the films based on gelatin with nanoparticles, the ionic conductivity decreases significantly. In relation to the electrolyte based on chitosan, the ionic conductivity is influenced by the amount of glycerol added. It was found that increasing the temperature to 80°C promotes the increase of ionic conductivity for all films studied.

Simulação de Dinâmica Molecular (MD) foi utilizada para se explorar propriedades estruturais e dinâmicas de eletrólitos poliméricos, poli(oxietileno), PEO, PEO-LiClO4 em três concentrações de sal e em duas temperaturas (373 e 500 K), visando contribuir para o entendimento do mecanismo pelo qual os íons são transportados na matriz polimérica. Nas simulações MD foi utilizado um modelo de átomos unidos para o PEO. O modelo do PEO (32 cadeias de PEO com peso molecular de 1175) foi validado pela comparação do fator de estrutura estático, S(k), calculado com o obtido por espectroscopia de espalhamento de nêutrons para o PEO puro. Um pico em vetor de onda pequeno foi observado no S(k) quando LiClO4 foi adicionado na matriz do PEO, indicando a presença de ordem estendida no PEO-LiClO4 fundido. Pares iônicos de contato foram observados, os quais são favorecidos quando a temperatura aumenta. As cadeias do PEO se tomam menos estendidas (menor raio de giração, Rg) com a adição de sal. O raio de giração aumenta com o aumento da temperatura em concentração baixa de sal e é fracamente afetado pela temperatura em concentração alta de sal. A dinâmica dos cátions é afetada pelo seu ambiente local, sendo mais favorecida na direção dos átomos de oxigênio do PEO. Os cátions apresentam movimentos difusivo e em saltos. A relaxação das cadeias do PEO, assim como a difusão dos íons, é maior nos sistemas de menor concentração de LiClO4 e em temperatura elevada. / In this work, Molecular Dynarnics (MD) simulation has been performed to evaluate structural and dynamics properties of the polymer electrolyte poly(oxietilene) PEO-LiClO4 for three salt concentration and two temperatures (373 and 500 K), in order to understand the ionic transport mechanism in the polymeric matrix. A united atoms model has been used for PEO. The PEO model has been validated by comparing calculated static structure factor S(k) of pure PEO at 363 K (32 PEO chains with a molecular weight of 1175) with previous experimental data obtained by neutron scattering spectroscopy. A low wave-vector peak indicates an extended-range order in PEO-LiClO4 melts. Contact ionic pair are observed, which are favoured as temperature increases. PEO chains as a whole becomes less extented (smaller radius of gyration) uppon addition of LiClO4. Radius of gyration increases with temperature at low salt concentration, but it is only marginally affected by temperature at high concentration. Cations dynamics is affected by the local neighborhood, being faster in the direction of PEO oxygen atoms. Cations motion display diffusion and hopping events. Relaxation time of PEO chains, as well as ionic diffusion, increase with temperature and decrease with LiClO4 concentration.

O óxido de cério (CeO2), quando dopado com óxidos de terras raras, tem sua condutividade iônica aumentada, possibilitando seu uso como eletrólito de Células a Combustível de Óxido Sólido de Temperatura Intermediária (IT-SOFC), que são operadas entre 500 e 700°C. Os aditivos ou dopantes mais eficientes para o aumento da condutividade iônica são a samária (óxido de samário Sm2O3) e a gadolínia (óxido de gadolínio Gd2O3), com concentrações molares entre 10 e 20%. Neste contexto foram sintetizados, neste trabalho, pós de composição Ce0,8(SmGd)0,2O1,9 pelas rotas de síntese por coprecipitação de hidróxidos, carbonatos e oxalatos. O efeito do tratamento hidrotérmico foi avaliado para pós precipitados com hidróxido de amônio. Utilizou-se, como matériasprimas, concentrados de terras raras contendo 90% em massa de CeO2 e outro contendo 51% de Sm2O3 e 30% de Gd2O3, ambos provenientes do processamento da monazita. Estes concentrados foram utilizados devido ao menor custo em relação às matérias-primas puras adquiridas comercialmente e a semelhança química dos demais elementos de terras raras contidos. Inicialmente, foram definidas as condições das etapas de coprecipitação e a influência da temperatura de calcinação nas características dos pós e produtos sinterizados. Os resultados obtidos mostraram que os pós calcinados na faixa de temperatura entre 450 e 800ºC apresentam elevada área de superfície específica (90-150 m2.g-1) e estrutura cristalina cúbica tipo fluorita da céria, indicando a formação da solução sólida. Observou-se, por microscopia eletrônica de varredura, que a forma das partículas e dos aglomerados é função do tipo de agente precipitante. As análises dilatométricas indicaram maior taxa de retração em temperatura próxima a 1300-1350ºC. Entretanto, valores elevados de densificação (>95% DT) são obtidos em temperaturas superiores a 1400ºC. A síntese por coprecipitação de hidróxidos seguida pelo tratamento hidrotérmico demonstrou ser uma rota promissora para cristalização, em baixas temperaturas (200oC), de nanopós à base de céria, mantendo-se elevados os valores de área de superfície específica (cerca de 100 m2.g-1). Cerâmicas com densificação superior a 95%DT foram obtidas em menores temperaturas de sinterização (1400oC), quando comparadas às provenientes de pós cristalizados por calcinação. / Cerium oxide (CeO2) when doped with rare earth oxides has its ionic conductivity enhanced, enabling its use as electrolyte for Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC), which is operated in temperatures between 500 e 700°C. The most effective aditives or dopants for ionic condutivity improvement are (samarium oxide Sm2O3) and gadolinia (gadolinium oxide Gd2O3), fixing the concentration between 10 and 20 molar%. In this work, Ce0,8(SmGd)0,2O1,9 powders have been synthesized by hydroxide, carbonate and oxalate coprecipitation routes. The hydrothermal treatment has been studied for powders precipitated with ammonium hydroxide. A concentrate of rare earths containing 90wt% of CeO2 and other containing 51% of Sm2O3 and 30% of Gd2O3, both prepared from monazite processing, were used as starting materials. These concentrates were used due the lower cost compared to pure commercial materials and the chemical similarity of others rare earth elements. Initially, the coprecipitation and calcination conditions were defined. The process efficiency was verified by ceramic sinterability evaluation. The results showed that powders calcined in the range of 450 and 800°C presented high specific surface area (90 - 150 m2.g-1) and fluorite cubic structure, indicating the solid solution formation. It was observed, by scanning electron microscopy, that morphology of particles and agglomerates is a function of precipitant agent. The dilatometric analysis indicated the higher rate of shrinkage at temperatures around 1300-1350°C. High densification values (>95% TD) was obtained at temperatures above 1400ºC. Synthesis by hydroxides coprecipitation followed by hydrothermal treatment demonstrated to be a promising route for crystallization of ceria nanopowders at low temperatures (200oC). High values of specific surface area were reached with the employment of hydrothermal treatment (about 100 m2.g-1). High density ceramics were obtained at lower temperatures (1400oC), compared to those employed for calcined powders.

Tendo como vantagem a elevada resistência ao choque térmico da zircônia:magnésia e a alta condutividade iônica da zircônia:ítria, compósitos dessas cerâmicas foram preparados por meio da mistura, em diferentes concentrações, de eletrólitos sólidos de ZrO2: 8,6 mol% MgO e de ZrO2: 3 mol% Y2O3, compactação e sinterização. A caracterização microestrutural foi feita por meio de difração de raios X e microscopia eletrônica de varredura. A análise do comportamento térmico foi feita por dilatometria. As propriedades elétricas foram estudadas por meio de espectroscopia de impedância. Foi feita uma montagem experimental para monitorar a resposta elétrica gerada em função do teor de oxigênio a altas temperaturas. Os principais resultados mostram que os compósitos cerâmicos são parcialmente estabilizados nas fases monoclínica, cúbica e tetragonal, e apresentam comportamento térmico similar ao apresentado por eletrólitos sólidos de zircônia:magnésia de dispositivos sensores de oxigênio. Além disso, os resultados de análise de espectroscopia de impedância mostram que a adição da zircônia:ítria melhora o comportamento elétrico da zircônia:magnésia, e que resposta elétrica gerada é dependente do teor de oxigênio a 1000 °C, mostrando ser possível construir sensores de oxigênio utilizando compósitos cerâmicos. / Taking advantage of the high thermal shock resistance of zirconia-magnesia ceramics and the high oxide ion conductivity of zirconia-yttria ceramics, composites of these ceramics were prepared by mixing, pressing and sintering different relative concentrations of ZrO2: 8.6 mol% MgO and ZrO2: 3mol% Y2O3 solid electrolytes. Microstructural analysis of the composites was carried out by X-ray diffraction and scanning electron microscopy analyses. The thermal behavior was studied by dilatometric analysis. The electrical behavior was evaluated by the impedance spectroscopy technique. An experimental setup was designed for measurement the electrical signal generated as a function of the amount of oxygen at high temperatures. The main results show that these composites are partially stabilized (monoclinic, cubic and tetragonal) and the thermal behavior is similar to that of ZrO2: 8.6 mol% MgO materials used in disposable high temperature oxygen sensors. Moreover, the results of analysis of impedance spectroscopy show that the electrical conductivity of zirconia:magnesia is improved with zirconia-yttria addition and that the electrical signal depends on the amount of oxygen at 1000 °C, showing that the ceramic composites can be used in oxygen sensors.