Electrical and Mechanical Properties of Grain-Boundary-Phase Controlled Silicon Nitride

Abstract

Silicon nitride has been known as one of the representative structural ceramic materials. To overcome its poor sinterability, oxide additives have been utilized. During sintering, these sintering aids were found to be liquid phase. And then, after sintering, these existed as glass or crystalline phase in the grain boundary. It has been reported that grain boundary phase drop off mechanical properties of Si3N4 ceramics at high temperatures. Therefore many researchers have investigated about grain boundary phase of Si3N4, in order to improve its mechanical properties and oxidation resistance. However, it has not been found that a new function to silicon nitride ceramics is provided by controlling composition of grain boundary phase. In this study, we investigated high ionic conductivity in Si3N4 ceramic is obtained by providing ionic conductive glass as grain boundary phase.