Effect of sintering temperature on microstructure and electrical properties of Zn centre dot Pr centre dot Co centre dot Cr centre dot La oxide-based varistors

摘要

The microstructure and electrical properties of varistors, which are composed of Zn centre dot Pr centre dot Co centre dot Cr centre dot La oxide-based ceramics, were investigated with different sintering temperatures. The increase of sintering temperature led to more densified ceramics, whereas it decreased the varistor voltage and nonlinear properties. The highest nonlinearity was obtained from 1230 deg C, with 77.9 in nonlinear exponent and 0.4 mu A in leakage current. As the sintering temperature increased, the donor concentration and density of interface states increased in the range of 0.90 x 10~18 to 2.59 X 10~18/cm~3 and 3.98 x 10~2 to 4.04 x 10~12/cm~2, respectively. The barrier height decreased with increasing sintering temperature, reaching a minimum (0.67 eV) at 1300 deg C.