Effect of Sb2O3 addition on the varistor characteristics of ZnO-Bi2O3-ZrO2-MtrO (Mtr = Mn, Co)

Abstract

Effect of Sb 2 O 3 addition on the varistor characteristics of pyrochlore-free ZnO-Bi 2 O 3 -ZrO 2 -M tr O (M tr = Mn, Co) system previously proposed has been studied. With Sb 2 O 3 up to 0.1 mol%, a gradual enhancement of densification and the grain growth inhibition were seen in the system sintered between 900 and 1200°C. In X-ray diffraction patterns, small amount of pyrochlore appeared in the specimens doped with Sb 2 O 3 (>0.06 mol%), which is thought responsible for the sintering behavior. Enhanced values of non linear coefficient (a) were obtained in ZnO-Bi 2 O 3 -ZrO 2 (ZBZ) doped with 0.001 mol% Sb 2 O 3 , but was leveled off at higher concentrations. In ZBZ added with M tr O (M tr = Mn, Co), significant increase of nonlinear coefficient (a > 30) along with low leakage current (I L «100 μA/cm 2 ) was attained. The α-enhancement effect of Sb 2 O 3 , however, was not observed in high-a ZBZ added with M tr O. As for degradation, addition of a trace amount (0.001 mol%)ofSb 2 O 3 to ZBZM tr was efficient, especially in I L .