Electric transport and enhanced dielectric permittivity in pure and Al doped NiO nanostructures

In this paper, we have studied the electrical and transport properties of Ni1-xAlxO(x = 0.00, 0.01, 0.03, 0.05) nanoparticles which have been synthesized through wet chemical route via a sol-gel method at 600 °C. The XRD patterns reveal that the NiO nanoparticles have a cubic polycrystalline crystal structure with average crystallite size ranging from 18.20 nm to 9.54 nm and 17.20 nm to 11.53 nm which are calculated by Debye-Sherrer and William Hall method, respectively. The morphology and size of the nanoparticles have also been observed by Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) for pure and Al-doped (5%) NiO nanoparticles. We have also studied the DC resistivity and activation energy (0.19 eV-0.49 eV) of our samples using two probe measurement. It is observed that pure and Al-doped NiO nanoparticles exhibit a giant value of dielectric permittivity (103-104). The high value of dielectric constant of Al-doped NiO nanoparticles depends on Al concentration and can be ascribed to the thermally activated and Maxwell-Wagner polarization mechanism.