Effect of Bi-Er-O addition on the electrical properties of ZnBiCoMnSb based varistor

In order to restrain the breakdown voltage gradient E1 mA at a low level and simultaneously improve nonlinear coefficient α, the rare earth element Er was doped into ZnBiCoMnSb based varistor ceramic in the form of Bi-Er-O phase. As a result, the excellent electrical performances including low E1 mA of 190 V/mm, high α of 55.6 as well as low leakage current IL of 2.5 μA/cm2 are obtained in 3 wt% Bi-Er-O phase modified ZnBiCoMnSb based varistor ceramic. It is found that the concentration of Er at grain boundaries is slightly higher than that in ZnO grains, while it is uniformly distributed throughout the bulk ceramic. This characteristic of element distribution mainly contributes to the enhancement of α by forming interface state densities and deep bulk traps at grain boundaries, rather than E1 mA. The reported herein strategy to restrain E1 mA and improve α at the same time on ZnBiCoMnSb based varistor ceramic can act as a reference for further fabrication of low-E1 mA varistor ceramics with excellent nonlinear performances by rare earth elements doping. [Display omitted]