Studies on ZnO ceramic varistors by deep heat treatment at 650\900 ℃ are reported. The current creep time curve exhibits a peak during the continuous action of a dc biasing voltage; the forward V I characteristic is ...Studies on ZnO ceramic varistors by deep heat treatment at 650\900 ℃ are reported. The current creep time curve exhibits a peak during the continuous action of a dc biasing voltage; the forward V I characteristic is improved rather than degraded after the action of the biasing voltage. We assume that the zinc interstitial cations Zn · i are out diffused rapidly and the concentration of Zn · i in the depletion layer is decreased rapidly during deep heat treatment; the oxygen anions O′ O could be accumulated at the grain interface if the out diffusion quantity of Zn · i is not enough to react with the O′ O ; the current creep phenomenon above results from the migration of the interface O′ O by the biasing voltage. We suggest an improved grain boundary defect model for the ZnO varistors by deep heat treatment, and examine the model using the experimental data of lifetime positron annihilation spectroscopy.展开更多
文摘Studies on ZnO ceramic varistors by deep heat treatment at 650\900 ℃ are reported. The current creep time curve exhibits a peak during the continuous action of a dc biasing voltage; the forward V I characteristic is improved rather than degraded after the action of the biasing voltage. We assume that the zinc interstitial cations Zn · i are out diffused rapidly and the concentration of Zn · i in the depletion layer is decreased rapidly during deep heat treatment; the oxygen anions O′ O could be accumulated at the grain interface if the out diffusion quantity of Zn · i is not enough to react with the O′ O ; the current creep phenomenon above results from the migration of the interface O′ O by the biasing voltage. We suggest an improved grain boundary defect model for the ZnO varistors by deep heat treatment, and examine the model using the experimental data of lifetime positron annihilation spectroscopy.
