Electrical characterisation and microstructure of metal oxide-doped ZnO varistors
1 Department of Physics, Obafemi Awolowo University, Ile-Ife. Nigeria
* Corresponding author: jakinnife@yahoo.com
* Corresponding author: jakinnife@yahoo.com
Abstract
Zinc oxide ceramic varistors were realized by doping ZnO with small quantities of MnO2 and PbO. The preparation technique of Direct Mixing of Constituent Phases (DMCP) was used. The samples were pelletized at a pressure of 1.24 X 103 N/cm2 and sintered in ambient atmosphere at a temperature of 850°C for a period of 36hours. They were characterized by measuring the current-voltage response to evaluate the non-ohmic behaviour. Breakdown threshold voltages of 2.02 X 103 V/m and 4.80 X 103 V/cm were recorded at currents 1.05 A/cm2 and 1.20A/cm2 respectively. Microstructural analyses were carried out using x-ray diffraction and scanning electron microscopy techniques. The XRD spectra re vealed the formation of structures and polymorphs of the additives in the sample while the SEM mi crographs revealed the sizes, types and distribution of grains in the matrix. The grain sizes for the re spective sample types were obtained as 1.621 µm and 1.020 µm. The microstructural analysis gave good correlation with the electrical response of the varistor samples.
Keywords
Ceramic varistors
electrical characteristics
threshold voltage
SEM micrographs
x-ray diffraction spectra
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How to Cite
O, A. J., & O, A. O. (2014). Electrical characterisation and microstructure of metal oxide-doped ZnO varistors. Nigerian Journal of Materials Science and Engineering, 5(1), 18-21.
A. J. O, and A. O. O, "Electrical characterisation and microstructure of metal oxide-doped ZnO varistors," Nigerian Journal of Materials Science and Engineering, vol. 5, no. 1, pp. 18-21, December 2014.
