Mixed conductivity, thermal expansion and defect chemistry of a-site deficient LaNi(0.5)Ji(0.5)O(3-delta)
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This work is focused on the analysis of defect chemistry and partial electronic and oxygen ionic conductivities of A-site deficient La1-xNi0.5Ti0.5O3-delta (x = 0.05 and 0.10). The orthorhombic-to-rhombohedral phase transition was monitored by means of dilatometry and high-temperature X-ray diffractometry. The average thermal expansion coefficients vary in the range (8.5-13.0) x 10(-6) K-1, increasing with temperature and A-site deficiency. The ion transference numbers determined by the Faradaic efficiency measurements are lower than 0.1% at 900-975 degrees C in air. Activation energies of the oxygen ionic conductivity at 897-977 degrees C are 430 and 220 kJ/mol for x = 0.05 and 0.10, respectively. Atomistic simulation demonstrated high stability of ternary defect clusters formed by the vacant sites in the A-sublattice, oxygen vacancies and W, cations, which leads to a very low level of mixed conductivity. © 2007, Elsevier Ltd.
Thermal expansion, Defects, Ionic conductivity, Electric conductivity, Perovskites, Oxygen
Yakovlev, S., Kharton, V., Yaremchenko, A., Kovalevsky, A., Naumovich, E., & Frade, J. (2007). Mixed conductivity, thermal expansion and defect chemistry of a-site deficient LaNi(0.5)Ji(0.5)O(3-delta). Journal of the European Ceramic Society, 27(13-15), 4279-4282. doi:10.1016/j.jeurceramsoc.2007.02.134