Generally, a high sintering tempera

Generally, a high sintering temperature (>1000 oC) is required to obtain high-dense ZnO ceramic by using a conventional sintering method, leading to a large amount of energy consuming[5]. Meanwhile, the high-temperature sintered ceramic usually possesses very large grain size, which may affect the electrical conductivity in a certain degree, as the electrical properties strongly depend on the density and microstructure uniformity[6]. Therefore, great efforts were made to reduce the sintering temperature. As a result, various sintering techniques were developed, such as hot press sintering[7], spark plasma sintering[8], two step sintering[9] and flash sintering[10], etc. However, the sintering temperature still stayed at high level.