CHENG Pengfei, LI Shengtao
(State key Laboratory of Electrical Insulation and Power Equipment，Xi' an J iaotong Univers ity, Xi' an 710049)
Abstract: It was found that the voltage gradient of outs ide layer of ZnO- Bi2O3 based varis tor ceramics doped with Ce2O3 and Gd2O3 is much higher than that of inner layer. This is called soft core phenomena. After s tudied on Zn binding energy by XPS, on dis tribution of additives by EDS, and on phase analys is by XRD, it was found that soft core phenomena are induced by three kinds of factors including shortage of oxygen and additives and faultines s of crys tallization in inner layer of samples .
Keywords: ZnO varis tor ceramics , soft core, dis tribution of oxygen and additives , crys tallization