Electrical Transport Properties of LaNi1-xTixO3 (x≤0.5) Ceramics

Abstract

Thermoelectric power and resistivity are measured for the perovskite <TEX>$LaNi_{1-x}Ti_xO_3$</TEX> (<TEX>$x{\leq}0.5$</TEX>) in the temperature range 77 K - 300 K. The measured thermoelectric power of <TEX>$LaNi_{1-x}Ti_xO_3$</TEX> (<TEX>$x{\leq}0.5$</TEX>) increases linearly with temperature and is represented by A + BT. The x = 0.1 sample showed metallic behavior, the x = 0.3 showed metal and insulating transition around 150 K, and x = 0.5 showed insulating behavior the over the whole temperature range. The electrical resistivity of x = 0.1 shows linear temperature dependence over the whole temperature range and <TEX>$T^2$</TEX> dependence. On the other hand, the electrical resistivity of x = 0.3 shows a linear relation between <TEX>$ln{\rho}$</TEX> and <TEX>$T^{-1/4}$</TEX> (variable range hopping mechanism) in the range of 77 K to 150 K. For x = 0.5, the temperature dependence of resistivity is characteristic of insulating materials; the resistivity data was fitted to an exponential law, such as ln(<TEX>${\rho}/T$</TEX>) and <TEX>$T^{-1}$</TEX>, which is usually attributed to a small polaron hopping mechanism. These experimental results are interpreted in terms of the spin polaron (x = 0.1) and variable range hopping (x = 0.3) or small polaron hopping (x = 0.5) of an almost localized <TEX>$Ni^{3+}$</TEX> 3d polaron.