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

Abstract

Co was added to see its effect on the electrical conductivity of Sr- and Mg-doped LaAlO3 (La0.9Sr0.1 Al0.9Mg0.1O3, LSAM). Electrical conductivities of La0.9Sr0.1(Al0.9Mg0.1)1− xCoxO3 (LSAMC) for x = 0–0.20 were measured using 2-probe a.c. and 4-probe d.c. method at temperature between 300 and 1300∘C in air, and as a function of Po 2 (1–10−15 atm) at 1200∘C. Electrical conductivities in air increased with increasing Co content, while their activation energy decreased. From the impedance spectroscopy analysis, it was found that both the grain and the grain boundary conductivities of LSAMC samples increased rapidly with Co-addition. LSAMC samples were oxygen ion conductors in low Po2 and mixed conductors in high Po 2 up to x = 0.1 just like LSAM. With Co-doping, p-type conductivities increased, however, ionic conductivities remained nearly constant.