Metal-insulator transition in ZnO nanopowder during thermal cycling by impedance spectroscopy

Abstract

We have investigated the electrical response on the pellet of ZnO nanopowder by impedance spectroscopy. Different trends of impedance plane plots have been discussed due to the modulations of relaxation time with temperatures. Thermal cycling induces irreversible changes in the resistance of the material which has been explained by incorporating the role of extended defects like oxidation of Zn interstitials at surfaces and intrinsic/extrinsic grain boundaries. Metal-insulator transition has been reported and discussed in term of combined effects of Zn interstitials and oxygen vacancies. Irreversible increase in the values of dielectric constant have been conferred with thermal cycling’s.

Metal-semiconductor transition in NiFe2O4 nanoparticles due to reverse cationic distribution by impedance spectroscopy

“…At each temperature, a decrease in the dielectric constant with frequency is observed owing to the lower dipolar response to the ac field. 39 Different types of conductivities in NiFe 2 O 4 material have been reported in the literature. Baruwati et al 40 attributed the n-type behavior as being due to the presence of Fe 3þ in NiFe 2 O 4 nanoparticles.…”

Realistic dielectric response of high temperature sintered ZnO ceramic: a microscopic and spectroscopic approach

“…In the pristine ZnO, polarization is generally governed by orientational polarization due to association of the Zn 2+ with oxygen vacancies, which have limited dipole moment. 57,58 In the present study, all the samples were heat treated at very high temperatures (1200-1400 C) and XAFS study shows that amount of V O and V Zn concentrations more or less remains the same in all the samples. Therefore, orientational polarization due to the Zn 2+ -V O dipoles remains x and it is the microstructure, which controls the overall dielectric constant in the whole frequency range of all the sintered ZnO ceramics.…”

Evidence for a capacitor network near the metal insulator transition in VO2 thin films probed by in-plane impedance spectroscopy

“…IS is shown to be a powerful tool to model such behavior. Recently, impedance spectroscopy (IS) has been used to investigate the MIT in ZnO nano-powders 8,9 , the resistive switching in NiO and TiO 2 thin films 10,11 , magnetoimpedance in MgO tunnel barriers 12 , surface pasivation in silicon 13 and BiMnO 3 thin films 14 . In each cases, IS gives relevant information about AC conduction.…”