Electrical properties of the system lanthanum lead cobalt titanium oxide

Abstract

Measurements of DC electrical resistivity and Seebeck coefficient on the perovskite system La_1−x Pb _x−δ Co_1−x Ti _x O_3−δ for 0·2≤x≤0·9 have been made in the temperature range 300–800 K. AC conductivity,σ _a.c, of all the samples were measured as a function of temperature (300–573 K) and frequency (1 kHz-1 MHz). DC resistivity behaviour of all the samples is similar. However, the resistivity value, which varies over 5–6 orders of magnitude, depends on both the compositionx and the structure of the samples. All the samples exhibitp-type electronic conduction. The value of Seebeck coefficient,α, for samples withx≤0·5 initially increases with temperature up to a particular temperature. Above this temperature, the behaviour ofα for samples withx≤0·5 and for samples withx>0·5 over the entire temperature range is similar to that of La CoO₃. All the samples exhibit frequency-dependent a.c. conductivity at low temperatures.