摘要
The effect of Mn_(3)O_(4)addition on microhardness,microstructure and electrical properties of vanadium oxide doped zinc oxide varistor ceramics is systematically investigated.The Vicker’s microhardness HV has decreased with increasing the amount of Mn3O4.Also,the average grain size has decreased from 27.51μm to 19.55μm with increasing the amount of Mn_(3)O_(4) up to 0.50 mol%,whereas an increase in Mn_(3)O_(4) up to 0.75 mol%has caused the average grain size to increase and then it decreases with increasing Mn_(3)O_(4)from 0.75 mol%to 1.00 mol%.The sintered density has decreased from 5.38 g/cm3 to 5.31 g/cm3 with increasing the amount of Mn_(3)O_(4).The varistor ceramic modified with 0.50 mol%Mn_(3)O_(4) has exhibited excellent nonlinear properties,with 16.29 for the nonlinear coefficient and 441.9μA/cm2 for the leakage current density.Furthermore,the sample doped with 0.50 mol%Mn_(3)O_(4) has been found to possess donor density as 0.77×10^(18) cm^(-3) and 0.916 eV barrier height.
