Resistance degradation of lead magnesium niobate-based ceramics during nickel electroplating and recovery through air annealing

Resistance degradation of lead magnesium niobate (PMN)-based relaxor ferroe lectrics during nickel electroplating, as well as the recovery of the degra ded specimen through air annealing, were investigated by using resistance m easurement and X-ray photoelectron spectroscopy (XPS). It was found that th e resistivity of the ceramics declined nonlinearly with the electroplating time, and eventually, an obvious degradation occurred. The XPS results show ed that parts of Pb2+ and Nb5+ were reduced to metallic Pb and Nb4+ by hydr ogen during electroplating. In view of defect chemistry, oxygen vacancies a nd free electrons were produced, leading to the resistance degradation. It was also found that the degraded PMN-based ceramics could regain its resist ivity characteristics after being annealed in air at high temperatures. The correlation of Pb and Nb4+ reoxidation and the resistivity recovery was cl arified, which in turn confirmed that the generation of metallic Pb and Nb4 + resulted in the resistance degradation of the ceramics during nickel elec troplating. (C) 2001 The Electrochemical Society.