Smart technique for fabrication of zinc oxide varistor

This paper describes a smart and industrially suitable technique for prepar ing a high performance ZnO varistor from doped zinc oxide powder. A homogen eous distribution of various dopants in the mixed powder has been achieved by coating ZnO powder with a mixed solution of dopants in the form of aceta tes, nitrates and citrates. The mixed powder on subsequent drying, calcinat ion. and sintering, produced varistors with better nonlinear electrical pro perties (alpha = 51) compared to varistors prepared from conventional oxide mixing technique (alpha = 30). The better nonlinear properties of solution coating route varistors have been attributed to the presence of uniform po tential barriers throughout the entire microstructure, which in turn is cre dited to the uniform distribution of dopant ions at each grain and grain bo undary region. (C) 2001 Elsevier Science Ltd. All rights reserved.