Kinked grain boundaries in alumina doped with Y2O3

Abstract

Polycrystalline alumina specimens with and without MgO doping show smoothly curved grain boundaries after heat treatment at 1400degreesC indicating their rough structure. When heat-treated at 1400degrees and 1500degreesC for 24 h after packing in an alumina-YAG powder mixture, many grain boundaries (without any liquid phase) develop kinks of large and small scales as observed by scanning electron microscopy and transmission electron microscopy. The addition of Y2O3 at concentrations close to the solubility limit is thus shown to induce the grain boundary transition to singular structures.