Mixed conductivity, thermal expansion and defect chemistry of A-site deficient LaNi0.5Ti0.5O3−δ

✍ Scribed by S. Yakovlev; V. Kharton; A. Yaremchenko; A. Kovalevsky; E. Naumovich; J. Frade

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 183 KB
• Volume: 27
• Category: Article
• ISSN: 0955-2219
• DOI: 10.1016/j.jeurceramsoc.2007.02.134

✦ Synopsis

This work is focused on the analysis of defect chemistry and partial electronic and oxygen ionic conductivities of A-site deficient La 1-x Ni 0.5 Ti 0.5 O 3-δ (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) × 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 • C in air. Activation energies of the oxygen ionic conductivity at 897-977 • 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 Ni 3+ cations, which leads to a very low level of mixed conductivity.