Papers by Keyword: Oxygen Ion Conductivity

Abstract: A Composite oxide ionic conductor consisting of La₁₀Si₆O₂₇ (LASIO) and Ce_0.9Gd_0.1O_1.95 (GDC) was synthesized by a modified sol-gel method. The La₁₀Si₆O₂₇ powders prepared by modified sol-gel synthesis were coated with GDC gel and latter calcined to form a La₁₀Si₆O₂₇ - Ce_0.9Gd_0.1O_1.95 composite material. The structural and microstructural properties of the composite were investigated using powder XRD, SEM and TMA. EIS was conducted in air on the sintered pellets to evaluate the electrochemical performance of the pellets. The conductivity of the composite electrolyte at 973 K was 26 mS /cm which is two orders of magnitudes higher than that for the pure LASIO but lower than that of the GDC (30 mS/cm). The thermal expansion of the composite electrolyte is similar to that obtained for the LASIO.

Abstract: In complex perovskite-type oxides which have been studied as cathode materials, the thermal expansion coefficient increases with the increase in the oxygen ionic conductivity. In the present study, with the aim to explain such a behavior, a research has been carried out from a chemical bond point of view. For oxides A1-xA′xB1-yB′yO with perovskite structure, the ionicity of the individual bond, A-O and B-O, and the thermal expansion coefficient of mixed compounds were estimated by using semiempirical methods. It has been shown that the thermal expansion coefficient and the oxygen ionic conductivity decrease with the increase in the difference of the ionicity between A-O and B-O bonds. It is also found that the tolerance factor and the specific free volume are linearly correlated with the difference of ionicity.