Densification and thermal conductivity of AIN doped with Y2O3, CaO, and Li2O

Small amounts of Li2O result in sintering in the AlN-Y2O3-CaO and AlN-CaO systems at firing temperatures <1600 degrees C. The effect is ascribed to reduction of the liquidus temperature. Furthermore, Li2O is removed by volatization at temperatures from 1300 degrees to 1600 degrees C, and its content decreases several ppm from the initial 0.3 wt%. Li2O-doped AlN specimens containing Y2O3 and CaO additives are well densified by firing at 1600 degrees C for 6 h, and their thermal conductivity is 135 W . m(-1). K-1. The effect of Li2O addition on sintering and thermal conductivity also is discussed through thermodynamic considerations.