Doping-induced dielectric and transport properties of Ni_1−xZn_xO

Ni_1−xZn_xO (with 0 ≤ x ≤ 0.05) nanoparticles are synthesized by chemical precipitation method in order to investigate the effect of Zn doping on the dielectric and transport properties of NiO. Prepared samples are characterized by means of X-ray diffraction (XRD) method, scanning electron microscope (SEM), and Transmission electron microscope (TEM). The size of the nanoparticles is calculated and found to be 26 nm and 22 nm for x = 0.0 and 0.05, respectively. Regular increase of the optical band gap with increase in doping concentration (x) is observed which is consistent with the variation of particle size. Frequency (f) dependence of AC (σ_ac) conductivity, dielectric constant (ε_r), and dielectric loss (tanδ) of Ni_1−xZn_xO (0 ≤ x ≤ 0.05) has been studied. It is observed that the dielectric constant (ε_r) increases gradually with x at high frequency (2 MHz). The dc conductivity (σ_dc) is found to decrease with Zn doping at room temperature which may be attributed to the reduction of oxygen vacancy. The temperature dependence of dielectric properties for x = 0.00, 0.05 are also investigated as a function of f. Cross over of dc conductivity of Ni_0.95Zn_0.05O to that of NiO observed around ~ 365 K indicates the lowering of activation energy of conductivity for x = 0.05 with increase in temperature.