Title :
Degradation of ZnO varistor and its dielectric relaxation
Author :
Wang, Huifang ; Xu, Yan
Author_Institution :
Dept. of Solid State Electron., Huazhong Univ. of Sci. & Technol., Wuhan
Abstract :
Dielectric relaxation spectra are used to study the degradation of a ZnO varistor under 8/20μs impulse current. The relationship between dielectric relaxation spectra and the distribution of migration ions is investigated. Dielectric-relaxation measurement is shown to be a reliable method for studying the degradation of non-Ohmic ZnO ceramics. The frequency spectra of dielectric loss are shifted to low-frequency regions after stressing by impulse current. The shift is attributed to the formation of equivalent dipoles in the grain boundary by the migration of interstitials
Keywords :
dielectric losses; dielectric relaxation; grain boundaries; interstitials; varistors; zinc compounds; 8 to 20 mus; ZnO varistor; ceramics; dielectric loss; dielectric relaxation; frequency spectra; grain boundary; interstitials; migration ions distribution; Capacitance measurement; Ceramics; Current measurement; Dielectric loss measurement; Dielectric losses; Frequency; Thermal degradation; Varistors; Voltage; Zinc oxide;
Conference_Titel :
Electrical Insulation and Dielectric Phenomena, 1993. Annual Report., Conference on
Conference_Location :
Pocono Manor, PA
Print_ISBN :
0-7803-0966-9
DOI :
10.1109/CEIDP.1993.378916
