Dielectric relaxation and conduction mechanism in LaNi3/4M1/4O3 (M = Mo, W) at low temperature

Abstract

In order to investigate the electrical transport in LaNi3/4Mo1/4O3 and LaNi3/4W1/4O3, the dc conductivity and dielectric properties in these polycrystalline materials are investigated in the temperature range from 163K to 383 K and frequency range from 50 Hz to 1 MHz. The X-ray diffraction patterns of the samples show monoclinic phase at room temperature. The homogeneity of the samples is determined by energy dispersive analysis of X-ray (EDAX) attached with a scanning electron microscope. The temperature dependence of dc conductivity shows the semiconducting nature of the materials. The complex impedance plane plots show that the relaxation (conduction) mechanism in these materials is purely a bulk effect arising from the semiconductive grains. The frequency-dependent electrical data are also analyzed in the framework of ac conductivity formalism. The ac conductivity spectra follow the universal power law. The activation energies required for bulk conduction is 0.143 and 0.165 eV for LNM and LNVV respectively. The scaling behaviour of loss tangent suggests that the relaxation describes the same mechanism at various temperatures.