京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22706号 / 工博第4753号 / 新制||工||1743(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 江口 浩一, 教授 陰山 洋, 教授 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

The development of a high-throughput impedance spectroscopy instrumentation platform for conductivity characterization of ion transport materials is outlined. Collaborative studies using this system are summarized. Charge conduction mechanisms and conductivity data for small molecule proton conducting liquids, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, and select mixtures of these compounds are documented. Furthermore, proton diffusivity measurements using a Pulse Field Gradient Nuclear Magnetic Resonance (PFG NMR) technique for imidazole and 1,2,3-triazole binary mixtures are compared. Studies of azole functionalized discotic and linear mesogens with conductivity, structural, and thermal characterizations are detailed.

My main objective is to gain a firm understanding of the correlation between the defect chemistry and the properties of Ba-based perovskite structure proton-conducting ceramics, especially B-site doped BaCeO3, so as to allow the engineering of these compounds with the desired properties for the application in devices; develop membranes of mixed protonic-electronic conductors suitable for hydrogen separation from gas mixtures; and further advance hydrogen separation technology by gaining fundamental understanding about electrochemical separation mechanism. BZCY proton conductors with various compositions have been synthesized and characterized. The absence of low-angle supercell reflections indicates a random B-site cation distribution. The substitution of Zr led to a decrease in cell volume and an enhanced structural stability against reactions with CO2. The total conductivity for BZCY pellets increased with temperature increased and decreased as the zirconium content increased at each fixed temperature. Dense Ni-BZCY composite membranes have been successfully fabricated for evaluating hydrogen permeability and stability. Doping Zirconium in the B-site only slightly reduced the hydrogen permeation at high temperatures, but dramatically increased the chemical stability in CO2- and H2O-containing gases. Among the compositions studied, the Ni-BZCY7 exhibited both highest H2 permeation rate and good chemistry stability, thus having potential for practical applications.

No description available.

À l'heure actuelle, le développement dans les piles à combustible gagne un regard considérable pour la cogénération de l'énergie propre. Plus particulièrement, les piles à combustible à conduction protonique dont leurs électrolytes sont des oxydes de type pérovskite. Nous nous sommes intéressés aux électrolytes des piles de type PCFC « Proton Ceramic Fuel Cell » dont la température de fonctionnement est intermédiaire. L'intérêt porté pour l'amélioration de la diffusion du proton au sein de ces matériaux implique une compréhension fondamentale de l'interaction du proton avec son environnement. Cette problématique a conduit à une étude systématique en appliquant l'approche de la théorie de la fonctionnelle de la densité sur les matériaux de BaMxZr1-xO3 (M=Y, In et Sc ; x=12,5, 25 et 37,5%). Dans un premier temps, la validation de la méthode appliquée sur le système idéal de BaZrO3 et BaZr0,625Y0,375O3 a été nécessaire afin de reproduire les propriétés électroniques, structurales et de vibration de phonon en bon accord avec les résultats expérimentaux. Dans un deuxième temps, la variation des propriétés électroniques et structurales en fonction de la nature du dopant accepteur (M=Y, In et Sc), sa répartition dans le réseau, et sa concentration ont été étudiées. Une distorsion locale autour de l'atome dopant dans le réseau a été obtenue. Par conséquent, une baisse de symétrie du réseau a été déterminée. Cette distorsion est remarquée quel que soit la nature du dopant. La différence la plus marquée de l'effet de la nature du dopant est trouvée sur les charges atomiques des ions oxygène selon trois environnement possible : Zr-O(1)-Zr, Zr-O(2)-M et M-O(3)-M. Une diminution de la charge (et donc diminution de la basicité) sur le site O3 est bien remarquée dans BaMxZr1-xO3. On attribue cette diminution de charge à la formation d'une liaison covalente à caractère anti-liant Y-O2 (O3). La liaison est ionique pour Sc-O2(O3) et covalente de faible caractère liant pour In-O2 (O3). Nous avons poursuivi nos investigations sur l'insertion d'hydrogène dans les matériaux étudiés. L'analyse des propriétés électroniques, structurales, des vibrations de phonon et l'énergie d'interaction de l'hydrogène des structures BaMxZr1-xO3H, nous ont permis d'établir une corrélation entre le caractère de la liaison chimique M-O, l'insertion du proton et la force de la liaison O-H. L'insertion de H sur le site O3 dans BaYxZr1-xO3 (x=0,25 et 0,375) n'est pas obtenue, probablement à cause de la faible basicité de l'ion oxygène dans la configuration Y-O3-Y. L'insertion du H sur le site O3 pour les deux configurations In-O-In et Sc-O-Sc est obtenue dans BaInxZr1-xO3 (x=0,25 et 0,375) et BaScxZr1-xO3 (x=0,25 et 0,375) respectivement. La variation de l'énergie d'interaction de l'hydrogène avec son environnement dévoile une stabilisation des défauts protoniques significativement plus importante dans le cas de l'atome dopant accepteur yttrium que dans le cas des dopants In et Sc. L'analyse des fréquences de vibration de valence de la liaison O-H a montrée que cette liaison est plus forte dans BaInxZr1-xO3 et BaScxZr1-xO3 que dans BaYxZr1-xO3. En conclusion, nos résultats démontrent que le matériau BaZrO3 dopé en Y favorise plus la formation des défauts protoniques avec une liaison O-H moins forte que dans les matériaux baryum zirconates dopés en In et Sc. / At the present, the development of fuel cells gains a significant interest for their application in clean energy technologies, more specifically, the proton conducting fuel cells. We are interested in the perovskite oxides electrolytes used in PCFC fuel cell “Proton Ceramic Fuel Cell” which operates at intermediate temperature. The interest for the improvement of proton diffusion in these materials necessitates a fundamental systematic understanding of the proton interaction with its environment. Therefore we applied Density Functional Theory based approach on ideal BaZrO3 and doped barium zirconates BaMxZr1-xO3 (M=Y, Sc and In ; x=12.5, 25 and 37.5%), currently known among the best candidates for PCFC electrolytes. First, the validation of the method applied to the ideal system and BaY0.375Zr0.625O3 was necessary in order to reproduce the electronic, structural and phonon vibration in good agreement with the experimental results. Second, the variation of electronic and structural properties and of the phonon vibration was studied as a function of acceptor dopant nature, positions in the lattice and concentration. A local distortion around the dopant atom in the lattice was obtained. Therefore a reduction of the symmetry system has been determined. This distortion is noticeable regardless of the nature of the dopant. The most striking difference due to the dopant nature is found for the atomic charges on three possible oxygen environments : Zr-O(1)-Zr, Zr-O(2)-M and M-O(3)-M. A decrease in the atomic charge of O3 site (decrease of basicity) is well observed in BaYxZr1-xO3. This decrease in the charge can be attributed to the formation of a covalent anti-binding Y-O2(O3) bond. The binding is ionic for Sc-O2 and slightly covalent with a maximum of 15% covalency for In-O2. Our next investigations were focused on the insertion of hydrogen in the studied materials. The analysis of the computed electronic and structural properties, phonon vibrations and hydrogen interaction energies allowed us to establish a correlation between the nature of the chemical bonding M-O, the insertion energy of the proton and the O-H bond strength. The insertion of hydrogen in O3 site in BaYxZr1-xO3 (x=0.25 and 0.375) is not obtained, probably due to the low basicity of the oxygen ion in the configuration Y-O-Y. The insertion of H at the oxygen site for both In-O3-In and Sc-O3-Sc configurations found to be energetically favored in BaInxZr1-xO3 (x=0.25 and 0.375) and BaScxZr1-xO3 (x=0.25 and 0.375) respectively. The variation of hydrogen interaction energy with its environment reveals a significantly stronger stabilization of proton defects in the case of yttrium acceptor dopant than in the two other barium zirconates doped with In and Sc. The analysis of O-H stretching vibration frequencies has shown that the O-H bond is stronger in BaInxZr1-xO3 and BaScxZr1-xO3 than in BaYxZr1-xO3. In conclusion, our results show that the Y doped barium zirconate material favors the formation of proton defects, with a weaker O-H bond than in In and Sc doped oxides.

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.

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.

Conventional oxygen anion conducting yttria-stabilized zirconia (YSZ) based solid oxide fuel cells (SOFCs) operate at high temperatures (800oC-1000oC). SOFCs based on proton conducting ceramics, however, can operate at intermediate temperatures (450oC-750oC) due to low activation energy for protonic defect transport when compared to oxygen vacancy transport. Fuel cells that operate at intermediate temperatures ease the critical materials requirements of cell components and reduce system costs, which is necessary for large scale commercialization. BaCeO3-based perovskite materials are candidates for use as ion conductors in intermediate temperature SOFCs (IT-SOFCs) when doped with trivalent cations in the B-site. B-site doping forms oxygen vacancies which greatly increases the electrical conductivity of the material. The oxygen vacancies are consumed during the creation of protonic defects or electronic defects, depending on the atmosphere and temperature range. High performance IT-SOFCs based on the Y3+ and Yb3+ doped BaCeO3-based system, BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (BZCYYb) have been recently reported. High conductivity in O2/H2O atmosphere was reported, however, a more basic understanding of the BZCYYb structure, electrical conductivity, and the portion of the charge carried by each charge carrier under fuel cell conditions is lacking. In this work, the BZCYYb material is fabricated by the solid state reaction method and the crystal structure at intermediate temperatures is studied using HT-XRD. The total conductivity of BZCYYb in H2/H2O, O2/H2O, and air atmospheres in the IT-SOFC temperature range is reported. The activation energy for transport at these conditions is determined from the conductivity data and the transference numbers of protonic defects, oxygen anion defects and electronic defects in the BZCYYb material are determined by the concentration cell - OCV method. BZCYYb is a mixed proton, oxygen anion, and electronic conductor at IT-SOFC temperature ranges (450oC - 750oC), in H2, O2, and H2O containing atmospheres. Ni-BZCYYb/BZCYYb/BZCYYb-LSCF fuel cells were constructed and peak power densities of ~1.2 W/cm2 were reported at 750oC after optimization of the Ni-BZCYYb anode porosity. Decreasing the Ni-BZCYYb anode porosity did not significantly affect the electrical conductivity of the anode, however the peak power densities of the IT-SOFCs based on the anode with less porosity, calculated from I-V curve data, showed dramatic improvement. The fuel cell with the lowest anode porosity demonstrated the highest performance. This finding is in stark contrast to the optimal anode porosity needed for high performance in YSZ-based, oxygen anion conducting SOFCs. Because of significant proton conduction in the BZCYYb material, fuel cell reaction products (water) form at the cathode side and less porosity is required on the anode side. The improvement in performance in the BZCYYb based IT-SOFC is attributed to the unique microstructure formed in the Ni-BZCYYb anode when no pore forming additives are used which may contribute to high electrocatalytic behavior for anode reactions. This work provides a basic understanding of the electrical properties of BZCYYb and clarifies the feasibility of using BZCYYb in each component of the IT-SOFC system as well as in other electrochemical devices. The high performance of the Ni-BZCYYb/BZCYYb/BZCYYb-LSCF IT-SOFC, due to low anode porosity, provides a new understanding for the rational development of high performance IT-SOFCs based on electrolytes with significant protonic conduction.

The work in this thesis mainly focuses on the preparation and characterization of several phosphates and solid oxide systems with the aim of developing new proton conducting materials for intermediate temperature fuel cells (ITFCs). Soft chemical methods such as sol-gel methods and conventional solid state methods were applied for the synthesis of these materials. Aluminum phosphate obtained by a solution method is single phase and belongs to one of the Al(H₂PO₄)₃ allotropies with hexagonal symmetry. The material is stable up to 200°C and decomposes into Al(PO₃)₃ at a higher temperature. The electrical conductivity of pure Al(H₂PO₄)₃ is on the order of 10⁻⁶-10⁻⁷ S/cm, very close to the value for the known proton conductors AlH₃(PO₄)₂•3H₂O and AlH₂P₃O₁₀•2H₂O. Much higher conductivity is observed for samples containing even a trace amount of excess H₃PO₄. It is likely that the conduction path gradually changes from grain interior to the surface as the acid content increases. The conductivity of Al(H₂PO₄)₃-0.5H₃PO₄ exhibited a good stability over the measured 110 hours. Although tin pyrophosphate (SnP₂O₇) has been reported to show a significantly high conductivity (~10⁻² S/cm) at 250°C in various atmospheres, we observed large discrepancies in the electrical properties of SnP₂O₇ prepared by different methods. Using an excess amount of phosphorous in the synthetic procedure generally produces SnP₂O₇ with much higher conductivity (several orders of magnitude higher) than samples with stoichiometric Sn:P ratios in their synthetic procedure. Solid state ³¹P NMR confirmed the presence of residual phosphoric acid for samples with excess starting phosphorous. Transmission Electron Microscope (TEM) confirmed an amorphous layer covered the SnP₂O₇ granules which was probably phosphoric acid or condensed phases. Thereby, it is quite likely that the high conductivity of SnP₂O₇ results mainly from the contribution of the residual acid. The conductivity of these samples exhibited a good stability over the measured 80 hours. Based on the observations for SnP₂O₇, we developed a nano core-shell structure based on BPO₄ and P₂O₅ synthesised by solid state methods. The particle size of BPO₄ using this method varied between 10-20 nm depending on the content of P₂O₅. TEM confirmed the existence of an amorphous layer that is homogeneously distributed. The composite exhibits the highest conductivity of 8.8×10⁻² S/cm at 300°C in air for 20% extra P₂O₅ and demonstrates a good stability during the whole measured 110 hours. Polytetrafluoroethylene (PTFE) was introduced into the composites in order to increase malleability for fabrication. The conductivity and mechanical strength were optimized by adjusting the PTFE and P₂O₅ content. These organic-inorganic composites demonstrate much better stability at elevated temperature (250°C) over conventional SiC-H₃PO₄-PTFE composites which are common electrolytes for phosphoric acid fuel cells (PAFCs). Fuel cells based on BPO₄-H₃PO₄-PTFE composite as the electrolyte were investigated using pure H₂ and methanol as fuels. A maximum power density of 320 mW/cm² at a voltage of 0.31 V and a maximum current density of 1.9 A/cm² at 200°C were observed for H₂/O₂ fuel cells. A maximum power density of 40 mW/cm² and maximum current of 300 mA/cm² 275°C were observed when 3M methanol was used in the cell. Phosphoric acid was also introduced into materials with internal open structures such as phosphotungstic acid (H₃PW₁₂O₄₀) and heteropolyacid salt ((NH₄)₃PW₁₂O₄₀), for the purpose of acquiring additional connections. The hybrids obtained have a cubic symmetry with enlarged unit cell volume, probably due to the incorporation of phosphoric acid into the internal structures. Solid state ³¹P NMR performed on H₃PW₁₂O₄₀-xH₃PO₄ (x = 0-3) showed additional peaks at high acid content which could not assigned to phosphorus from the starting materials, suggesting a strong interaction between H₃PW₁₂O₄₀ and H₃PO₄. The conductivity of hybrids was improved significantly compared with samples without phosphoric acid. Fourier transform infrared spectra (FT-IR) suggest the existence of large amount of hydrogen bonds (OH••••O) that may responsible for the high conductivity. A H₂/O₂ fuel cell based on H₃PW₁₂O₄₀-H₃PO₄-PTFE exhibited a peak power density of 2.7 mW/cm² at 0.3 V in ambient temperature. Solid oxide proton conductors based on yttrium doped BaZrO₃ were investigated by introducing potassium or lanthanum at the A-sites. The materials were prepared by different methods and were obtained as a single phase with space group Pm-3m (221). The unit cell of these samples is slightly smaller than the undoped one. The upper limit of solid solution formation on the A-sites for potassium is between 5 ~ 10% as introducing more K results in the occurrence of a second phase or impurities such as YSZ (yttrium stabilized zirconium). K doped Barium zirconates showed an improved water uptake capability even with 5% K doping, whereas for La doped ones, water uptake is strongly dependent on particle size and synthetic history. The conductivity of K doped BaZrO₃ was improved by a factor of two (2×10⁻³ S/cm) at 600°C compared with undoped material. Fuel cells based on Pt/Ba₀₋₉₅K₀₋₀₅Zr₀₋₈₅Y₀₋₁₁Zn₀₋₀₄O[subscript(3-δ)]/Pt under humidified 5% H₂/air conditions gave a maximum power density 7.7 mWcm⁻² at 718°C and an interfacial resistance 4 Ωcm⁻². While for La doped samples, the conductivity was comparable with undoped ones; the benefits of introducing lanthanum at A-sites may not be so obvious as deficiency of barium is one factor that leads to the diminishing conductivity.

In this thesis, the focus is on studying BaZrO3-BaCeO3 based proton conductors due to that they represent very promising proton conductors to be used for Intermediate Temperature Solid Oxide Fuel Cells (ITSOFCs). Here, dense BaZr0.5Ce0.3Y0.2O3-δ (BZCY532) ceramics were selected as the major studied materials. These ceramics were prepared by different sintering methods and doping strategies. Based on achieved results, the thesis work can simply be divided into the following parts: 1) An improved synthesis method, which included a water-based milling procedure followed by a freeze-drying post-processing, was presented. A lowered calcination and sintering temperature for a Hf0.7Y0.3O2-δ (YSH) compound was achieved. The value of the relative density in this work was higher than previously reported data. It is also concluded that this improved method can be used for mass-production of ceramics. 2) As the solid-state reactive sintering (SSRS) represent a cost-effective sintering method, the sintering behaviors of proton conductors BaZrxCe0.8-xLn0.2O3-δ (x = 0.8, 0.5, 0.1; Ln = Y, Sm, Gd, Dy) during the SSRS process were investigated. According to the obtained results, it was found that the sintering temperature will decrease, when the Ce content increases from 0 (BZCLn802) to 0.3 (BZCLn532) and 0.7 (BZCLn172). Moreover, the radii of the dopant ions similar to the radii of Zr4+ or Ce4+ ions show a better sinterability. This means that it is possible to obtain dense ceramics at a lower temperature. Moreover, the conductivities of dense BZCLn532 ceramics were determined. The conductivity data indicate that dense BZCY532 ceramics are good candidates as either oxygen ion conductors or proton conductors used for ITSOFCs. 3) The effect of NiO on the sintering behaviors, morphologies and conductivities of BZCY532 based electrolytes were systematically investigated. According to the achieved results, it can be concluded that the dense BZCY532B ceramics (NiO was added during ball-milling before a powder mixture calcination) show an enhanced oxygen and proton conductivity. Also, that BZCY532A (NiO was added after a powder mixture calcination) and BZCY532N (No NiO was added in the whole preparation procedures) showed lower values. In addition, dense BZCY532B and BZCY532N ceramics showed only small electronic conductivities, when the testing temperature was lower than 800 ℃. However, the BZCY532A ceramics revealed an obvious electronic conduction, when they were tested in the range of 600 ℃ to 800 ℃. Therefore, it is preferable to add the NiO powder during the BZCY532 powder preparation, which can lower the sintering temperature and also increase the conductivity. 4) Dense BZCY532 ceramics were successfully prepared by using the Spark Plasma Sintering (SPS) method at a temperature of 1350 ℃ with a holding time of 5 min. It was found that a lower sintering temperature (&lt; 1400 ℃) and a very fast cooling rate (&gt; 200 ℃/min) are two key parameters to prepare dense BZCY532 ceramics. These results confirm that the SPS technique represents a feasible and cost-effective sintering method to prepare dense Ce-containing BaZrO3-BaCeO3 based proton conductors. 5) Finally, a preliminary study for preparation of Ce0.8Sm0.2O2-δ (SDC) and BZCY532 basedcomposite electrolytes was carried out. The novel SDC-BZCY532 based composite electrolytes were prepared by using the powder mixing and co-sintering method. The sintering behaviors, morphologies and ionic conductivities of the composite electrolytes were investigated. The obtained results show that the composite electrolyte with a composition of 60SDC-40BZCY532 has the highest conductivity. In contrast, the composite electrolyte with a composition of 40SDC-60BZCY532 shows the lowest conductivity. In summary, the results show that BaZrO3-BaCeO3 based proton-conducting ceramic materials represent very promising materials for future ITSOFCs electrolyte applications. / <p>QC 20150423</p>