The Study Of Effection On Doping To Electric And Microstructure Property Of ZnO Varistors

ZnO varistors with highly nonlinear voltage-current characteristic,excellent surge withstanding capability and wide range working stability are employed to protect electrical circuits in the fields of electrical and electronics.In this article,nanosize ZnO composite powders were prepared by Sol-Gel which were needed in experiment,the optimum technological conditions were obtained through the study of Sol-Gel technological,and nanosize ZnO composite powders thta prepared by Sol-Gel were characterized.Finally,the influence of rare earths oxide(Y₂O₃,CeO₂,La₂O₃,Eu₂O₃) introducing to ZnO varistors on the electrical and microstructure properties of varistor were studied.The optimum technological conditions were sdudied through massive experiments. The suitable xerogel calcining temperature(500 to 700℃)was Determined by thermal analysis.And the ZnO composite powders were characterized,the rare earths oxide doped nanosize ZnO composite powders that body shape were sphere,grain-size distributing were even,particle size were approximately 54nm,specific surface area were about 1.21×10⁵m²/kg were obtained.Finally,system analysis were carryed on to electric properties of ZnO varistors with rare earths oxide(Y₂O₃,CeO₂,La₂O₃,Eu₂O₃) doped,and the reasons were multianalysised from microstructure and phase structure,ZnO crystal grain became tinier and distribution evener after the rare earths oxide doped.Electric properties of ZnO varistors distinct improved after rare earth elements doped,the voltage and voltage rating distinct enhanced, the nonlinear exponent and leakage current improved.Through the analysis,the primary causes that the electric performance of ZnO varistors enhanced was that through rare earth elements dopping changed the ZnO crystal grain size and other phases formation.