The effect of Ti addition on the electrical conductivity of Sr- and Mg-doped LaAlO3

Abstract

Ti was added into acceptor-doped LaAlO3 to enhance the mixed electronic and ionic conductivity at low Pot. Electrical conductivities of [La0.9Sr0.1Al0.9Mg0.1O3](1-x)[La2/3TiO3](x) (LAT) for x = 0 - 0.30 were measured using 4-probe d.c. method at temperatures between 1000 and 1300 C and as a function of oxygen partial pressure (Po-2 =1 similar to 10(-15) atm) at 1200 C. Electrical conductivities in air decreased with increasing Ti contents (x) for 0 < x < 0.15, and increased for 0.15 < x < 0.30 after showing minimum values at x = 0.15. The activation energy in air showed percolative change near x similar to 0.13. LAT samples for 0 <= x <= 0.10 were oxygen ion conductors in low Pot and mixed (p-type and ionic) conductors in high Pot. However, for x >= 0.15, n-type conductivity was dominant in low Pot. For x >= 0.20, the p-type conductivity in high Pot disappeared and the n-type conductivity was dominant in all Pot range and increased with increasing Ti concentration. (c) 2005 Elsevier B.V. All rights reserved.