Effect of erbium-calcium manganite doping on microstructure and electrical properties of zinc oxide based varistor ceramics

Abstract

In this research, (80-x) mol% zinc oxide with 20 mol% CaMnO₃ as the additive and (x) mol% erbium oxide Er₂O₃ as the doping material where x = 0.5, 1.0 and 1.5. Aims of this work are to elucidate the effects of doping material on microstructure ZnO and nonlinear characteristics of ZnO based varistor ceramics. A compound comprising ZnO-CaMnO₃-Er₂O₃ underwent pre-sintering at 500 °C for 4 hours and sintering process at temperature of 1100 °C, 1200 °C and 1300 °C with the soaking time of 1.5 hours and 4.5 hours. X-ray diffraction patterns CaMnO₃   spinal  and  additional  phases  containing Er in the confirmed the presence of synthesized compounds.

The disappeared of hydroxyl and carbonyl functional group was observed at 3600-3650 cm^-1, 1421 cm^-1 and 875 cm^-1 respectively by Fourier Transform Infrared spectroscopy to indicate the starting formation oxide metal upon calcinations.

Keywords: ZnO varistor; Er doping; microstructure; I-V characteristics; low voltage varistor