AUGER-ELECTRON SPECTRA OF PRASEODYMIUM-DOPED AND COBALT-DOPED ZNO VARISTOR

The distribution of elements in Pr-doped ZnO varistors was analyzed by means of an Anger electron spectra (AES) method. The samples used wer e ZnO varistor doped with Pr, Co, Ca, Cr and Ii ions. BES were obtaine d from fresh fractured surfaces to prevent surface contamination, The results indicated that Pr, K, and Ca ions segregated in a grain bounda ry region. No peak, corresponding to the Co ion, was found, indicating that the Co ions homogeneously dissolved into ZnO grains. Changes in AES profiles with the concentration of the dopants were observed for a KL23L23 transition of O ion. The KL23L23 transition consisted of four peaks whose intensity ratio varied with the concentration of the dopa nts, The effect of dopant, i. e, Co ion, on the AES were discussed on the basis of molecular orbital calculation for a cluster model [MZn9O1 0] (M=Zn, Co).