Structural and Electrical Properties of Zn1-xCrxO NTCR Nanoceramics Synthesized by High Energy Ball Milling

Abstract Cr doped ZnO (x = 0-0.04) nanoceramics was successfully synthesized by high energy ball milling (HEBM) technique. The structural and electrical properties of the synthesized sample has been studied in detail. The doping of Cr into ZnO has been verified by X-ray diffraction (XRD) and also from the variation in structural parameters. Rietveld refinement XRD pattern of calcined sample showed the hexagonal wurtzite structure and it did not induce impurity phases. From the XRD, it has been confirm that maximum result confirms that up to 4 atomic% of Cr can be doped into ZnO. The strain of the sample reduced with increase in particle size. After sintering, there is a growth of particle size of Cr doped ZnO sample. The impedance spectroscopy data shows a single semicircle in the high frequency region corresponding to the bulk properties of the nanoceramic sample. The decrease in real part of the impedance with temperature suggests the NTCR behavior of the sample in the temperature range of 300-500 ºC. The temperature dependent relaxation phenomena are also observed for the synthesized ceramic sample at high temperature. Distributed relaxation time suggests that the relaxation in the synthesized samples is of non-Debye type. The equivalent electrical circuit of the semicircular pattern in the impedance spectrum of ZnO and Zn1-xCrxO nanoceramics sample is a parallel combination of bulk resistance (Rb) and bulk capacitance (Cb).