Microstructure and electric properties of SrTiO3 based varistor.

The effect of MgO addition on the microstructure and the electronic properties of the SrTiO3-based varistor have been investigated. The addition of MgO on the calcined powder contributed to an increase in nonlinear coefficient (α). The MgO promoted grain growth in sintering process. After sintering, MgO existed at the grain boundary and effected on the oxygen diffusion. The capaci tance of the grain and the grain boundary was decreased by the addition of MgO. As the result, the height of Schottkey barrier increased with the addition of MgO.We thought that the increase of nonlinear coefficient (α) was the result of inrrpnsp in hpight nf Schottky barrier.