AlN ceramics prepared by high-pressure sintering with La2O3 as a sintering aid

Aluminum nitride ceramics with La2O3 as a sintering aid were obtained under high pressure (5.0 GPa) in a cubic anvil high-pressure and high-temperature apparatus. The results showed that the method could effectively lower the sintering temperature and shorten the sintering time. Under 5.0 GPa, the lowest sintering temperature was 1300 °C, which was above 300 °C lower than that for conventional liquid-phase sintering. The lattice parameters of the specimens sintered at high pressure were found to decrease by about 0.09% than that of the AlN powder, and residual compressive stress was found, while hexagonal lattice of AlN was not changed.