Synthesis and high-temperature thermoelectric properties of Ni and Ti substituted LaCoO 3

Abstract

The effect of Ti and Ni substitution in LaCoO 3− δ was investigated by means of electrical resistivity and Seebeck coefficient properties in a broad temperature range. The studied compounds crystallize in a rhombohedral crystal structure within the whole substitution range. The Seebeck coefficient of most of the studied compounds is positive indicating predominant hole-type charge carriers. The electrical resistivity decreases with increasing temperature for all compositions. Increasing the Ni content results in a decrease of the electrical resistivity, while the resistivity increases with increasing Ti content. The power factor, PF, for the Ni substituted samples is PF=1.42×10 −4 W/m 2 K for x = 0.10 at T = 540 K and decreases with temperature. The LaCo 1− x Ti x O 3± δ compounds reveal an enhancement of the power factor with increasing temperature. Ti substitution leads to a higher power factor compared to that of Ni substitution at T = 1240 K .