Electrical and thermal transport properties of Ni1-xCexO nanostructures

Abstract

In this report, we discussed the structural, electric conduction (DC and AC) mechanisms and thermal properties such as specific heat (CP) and change in enthalpy (ΔH) of Ni1-xCexO (x = 0.00, 0.01, 0.03 and 0.05) nanostructures synthesized by the sol-gel method which have been explored through LCR and differential thermal analysis (DTA) measurements. The dielectric relaxation in this system has also been discussed as a function of both frequency (75 kHz–1 MHz) and temperature (30 °C to 300 °C). In the light of several theoretical models, the AC conductivity has been analyzed using a power law σac∝ωs (s < 1), where frequency exponent ‘s’ examined as a function of temperature. Our experimental investigations based on theoretical models suggest that the AC conduction mechanism in all samples successfully described by non-overlapping small polaron tunnelling model (NSPT) and correlated hopping model (bipolaron hopping over single polaron hopping) (CBH) which provide reasonable physical parameters such as polaron hopping energies (WH and WM), characteristic relaxation time (τo=10−13 s), tunnelling distance (Rw) and density of states at Fermi level N(EF) as well as the concentration of a pair of defects sites (N), respectively. Also, specific heat and change in enthalpy (ΔH) have been discussed and it is observed that value of change in enthalpy (ΔH) decreases with increasing Ce concentration in NiO lattice.