Smart technique for fabrication of zinc oxide varistor

This paper describes a smart and industrially suitable technique for preparing a high performance ZnO varistor from doped zinc oxide powder. A homogeneous 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 acetates, nitrates and citrates. The mixed powder on subsequent drying, calcination. and sintering, produced varistors with better nonlinear electrical properties (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 potential barriers throughout the entire microstructure, which in turn is credited to the uniform distribution of dopant ions at each grain and grain boundary region. (C) 2001 Elsevier Science Ltd. All rights reserved.