Low-Temperature Synthesis of 10 mol% Gd₂O₃-Doped CeO₂ Ceramics and Its Characterization

抄録

10 mol% Gd₂O₃-doped CeO₂ solid-solution (20GDC) powders have been synthesized via carbonate coprecipitation using nitrates as the starting salts and ammonium hydrogen carbonate (AHC) as the precipitant. Characterizations were achieved by elemental analysis, XRD, DTA/TG, and FESEM. The thus-processed precursor is an amorphous hydroxyl carbonate with an approximate formula of Ce_0.8Gd_0.2(OH)(CO₃)•2H₂O, which directly yield oxide solid-solutions upon thermal decomposition at a very low temperature of approximately 430°C without any phase detected corresponding to Gd₂O₃. The 20GDC oxide powder calcined at 700°C shows excellent reactivity and were densified to >99% of the theoretical via pressureless sintering at a low temperature of 1150°C for 6 h. Electrical conductivity of the densified ceramic was measured in air in the range 400-700°C by the DC three-point method, and an activation energy of ∼60.92 kJ/mol was derived from the experimental data.