Impedance spectroscopy and conduction mechanism of Zn1-xMgxO NTCR ceramics

A simple solid-state reaction method has been used to synthesize Magnesium doped Zinc Oxide (Zn1-xMgxO, x = 0, 0.01, 0.02 and 0.03) ceramic samples with varying doping concentration. The phase analysis of the synthesized samples was carried out using X-ray diffraction (XRD). The negative temperature coefficient of resistance (NTCR) behaviour and the conductivity of the synthesized samples were studied using impedance spectroscopy. The synthesized samples show single-phase hexagonal wurtzite structure indicating successful doping of magnesium in ZnO lattice. The complex impedance behaviour of the synthesized sample shows a decrease in resistance with increase in temperature i,e the Negative Temperature Coefficient of Resistance (NTCR) nature. The AC conductivity of the synthesized sample was found to follow the correlated barrier hopping (CBH) model in the investigated temperature and frequency range. The equivalent electrical circuit of ZnO and Mg doped ZnO ceramic sample shows a parallel combination of bulk resistance (Rb) and bulk capacitance (Cb).