Fabrication and electrical characteristics of fine-grained ZnO varistors with crystal orientation for multilayer ceramic devices

Abstract

ZnO varistors are able to be successfully fabricated containing c-axis oriented fine grains of 2.5–2.8 µm for the first time, by using fine hexagonal templated ZnO. The crystalline orientation is clarified to have significant effects on the electrical behaviors of grain boundaries, even with low orientational degree (e.g., as Lotgering factor of 0.116). Break down voltage per a grain boundary (V_gb) and ε_r decrease by 16 and 5 % in perpendicular direction to the c-axis alignment from those in parallel, respectively. The control of crystal orientation has a possibility of leading to further advance in protection performance of ZnO-based multilayer varistors.