Title : Transport and thermodynamic properties of ni1-xcexo nanostructures
Abstract:
The conduction characteristics of Ni1-xCexO (x = 0.00, 0.01, 0.03 and 0.05) nanostructures prepared by the sol-gel method have been investigated through DC and AC measurements. The dielectric relaxation in this system have also been discussed as a function of both of frequency (75 kHz to 1 MHz) and temperature (30 0C to 300 0C). In the light of several theoretical models, the AC conductivity has been analyzed using a power law σ_ac∝ω^s (s< 1), where frequency exponent ‘s’ has been examined as a function of temperature. The experimental and theoretical investigations confirmed that the AC conduction mechanism in all samples could be successfully described by non-overlapping small polaron tunneling model and correlated hopping model (bipolaron hopping over single polaron hopping) which provided reasonable physical parameters such as polaron hopping energies (WH and WM), characteristic relaxation time ( =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. Besides this, based on specific heat and change in enthalpy (ΔH), it suggests that less heat generated in Ce doped NiO when compared to pure NiO nanoparticles.
