Remarkably improved electrical conductivity of ZnO ceramics by cold sintering and post-heat-treatment

Abstract High quality ZnO ceramics are required for transparent conductive oxide (TCO) films. In this work, high dense ZnO ceramics with density of ~ 97.5% were sintered by using Cold Sintering Process (CSP), and various post-heat-treating conditions (different types of atmosphere and temperature) were applied to optimize the microstructure and electrical conductivity. After post-heat-treatment, the crystallinity was improved, the relative density increased to > 99.0%, while the grain size exhibited small variations. The most significant improvements in electrical conductivity were observed for the sample post-heat-treated in Ar atmosphere, with more than four orders of enhancement from 0.0005 S/cm for the as-cold-sintered one to a maximum of 16.4 S/cm after post-heat-treating at 500 °C. Our work demonstrated an effective method for preparing high performance ZnO ceramics at ultralow temperature.