Knowledge of thermal behavior of electrolyte is important for fuel cell fabrication. In this study, using high‐temperature X‐ray diffraction analysis (HT‐XRD) and thermo‐mechanical analysis (TMA), a systematic investigation of lattice constants was performed on Y‐doped BaZrO3, which is a promising candidate for electrolyte in protonic ceramic fuel cells. The results revealed that a chemical expansion was observed between 300°C and 450°C during the heating process in HT‐XRD, and was attributed to the dehydration of BZY. Furthermore, it was found that the lattice constants of the samples doped with Y, Sm, Eu, and Dy were larger for the ones finally heat‐treated at 1600°C for sintering than those heat‐treated at 1300°C for synthesizing. The similar behavior was not observed in Sc‐doped samples.

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The precipitation condition of LaPO 4 in phosphoric acid solution was investigated under both atmospheric and humidified conditions. The crystal morphology, Sr doping level, H 2 O incorporation, and high temperature stability of Sr-doped LaPO 4 precipitates were also analyzed. Increasing pH 2 O from 0.01 to 1 atm extends the precipitation region of LaPO 4 in phosphoric acid solutions toward higher temperatures by nearly 100 °C. Under such conditions (e.g. T = 250 °C and pH 2 O = 1 atm), it is possible to obtain aggregated crystals up to 200 μm. The Sr doping level in LaPO 4 shows a strong dependence on the precipitation ratio of La, X La. The Sr doping level is higher in the low X La region, reaching 20 mol% at maximum. This value is one order of magnitude higher than the previously reported solubilities. It was confirmed H 2 O is certainly incorporated in the bulk by Sr doping. The solubility of Sr in LaPO 4 would be sufficiently high (at least 20.1 %) even at 600 °C; however, it becomes considerably lower at 1200 °C.

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Doped lanthanum polyphosphate (LaP 3 O 9 ) exhibits relatively high proton conductivity. For the practical applications such as the electrolyte of fuel cells, however, its conductivity must be improved by 2 orders of magnitude. Protons are introduced into matrix by lower-valent cation doping, and proton conductivity depends on dopant species. To date, LaP 3 O 9 has been doped with only Ca, Sr and Ba. In this work, we tried to dope LaP 3 O 9 with Na + , K + , Mg 2+ and Pb 2+ , as the new dopant species, due to their close ionic radii to La 3+ . Among them, only Pb could substitute for La at a comparable concentration to those of alkaline earth metals and its highest doping level was 6.4 mol% (Doping level is defined as the concentration ratio of dopant (M) to host cation (La) site in matrix (≡M/(La + M) × 100 (mol%))). Though Pb can exist as either divalent or tetravalent state, Pb in LaP 3 O 9 was identified to be divalent state by XPS analysis. Proton conduction was demonstrated by H/D isotope effect. The electrical conductivity of Pb-doped LaP 3 O 9 increased with Pb-doping level, owing to the increase in proton concentration. The conductivity of 4.5 mol% Pb-doped LaP 3 O 9 was about one order of magnitude lower than that of 7.9 mol% Sr-doped LaP 3 O 9 .

The concentrations of impurities in BaZroesYo ΐ5θ 3 . δ were qualitatively measured by GD-MS, and the concentrations of carbon, nitrogen, sodium, silicon, sulfur, chlorine, hafnium, and platinum were found to be more than 100 ppm. Among these identified impurities, we investigated the influence of sodium and silicon on grain boundary resistance of BaZrossYo 15Ο3.5. It was found that silica or silicate precipitated at grain boundary of BaZrossYo is0 3 . 5 and prevented the proton conduction of BaZr 0 8 5Yo ΐ5θ 3 . δ at the grain boundary, but sodium did not affect either bulk or grain boundary resistance. Also, we investigated which steps of the applied procedure causes the increase in the silicon concentration of BaZro^Yo ΐ5θ 3 . δ during the synthesis process of the widely-used solid state reaction method.Drying the powder in atmospheric air and using the heated glass flask were found to be major problems.With this knowledge, we reduced the silicon concentration of sintered BaZr 0 8 5Yo is0 3 . 5 to 120 ppm.

9 Ti 8 (Ti 濃度 : 47 mol%) の二相に分離する。 Bi 9 Ti 8 は密度差から液体 Bi の表面に浮上するため 17) ，これを回 収して合金中の Ti を濃縮する。その後，蒸留 (Distillation) 工程で の真空蒸留により Bi と Ti を分離する。なお，還元工程の副生成 物である塩化マグネシウム (MgCl 2 ) は，Kroll 法で行われている従 来の溶融塩電解法 (Mg 電解と呼ばれる ) によって Mg と塩素 (Cl 2 ) 高温での固液分離および真空蒸留を利用した Bi-Ti 合金からの Ti の分離 * Separation of Ti from Bi-Ti alloy by Solid-Liquid Separation at High Temperature and Vacuum DistillationA new Ti smelting process via. Bi-Ti alloy is proposed. This process comprises reduction of TiCl 4 to Bi-10 mol%Ti alloy by Bi-Mg alloy, precipitation of Ti-rich compound from the alloy, and vacuum distillation. In this study, we investigated the precipitation and distillation processes.In the precipitation process, the Bi-10 mol%Ti liquid alloy is cooled from 900 ℃ to 500 ℃ to precipitate Bi 9 Ti 8 in the liquid alloy. The Bi 9 Ti 8 is recovered by a two-step separation method: recovery of mixture of Bi 9 Ti 8 and Bi and further removal of Bi by centrifugal filtration. We demonstrated the recovery of mixture. As the results, Ti concentration in the mixture was 31 mol%, and the Ti yield was about 45 %. Because the remained liquid alloy after the recovery contains a large amount of Bi 9 Ti 8 , it is required to reuse the remained alloy in the precipitation process. Assuming the reuse of remained alloy, the material flow of the process was designed based on the experimental results. The centrifugal filtration of the mixture of Bi 9 Ti 8 and Bi was also carried out at 500 ℃ . By the centrifugal filtration at 50 G, alloys with a size of 1.5 mm were obtained, and the Ti concentration in the alloys was increased from 31 mol% to 40 mol%.Vacuum distillation of alloy powder and ingot was demonstrated. The distillation rate was enhanced when using the powder than when using alloy ingot as a starting material.