Densification and Thermal Conductivity of AIN Doped with Y 2 O 3 , CaO, and Li 2 O

Small amounts of Li 2 O result in sintering in the AIN‐Y 2 O 3 ‐CaO and AIN‐CaO systems at firing temperatures <1600°C. The effect is ascribed to reduction of the liquidus temperature. Furthermore, Li 2 O is removed by volatization at temperatures from 1300° to 1600°C, and its content decreases several ppm from the initial 0.3 wt%. Li 2 O‐doped AIN specimens containing Y 2 O 3 and CaO additives are well densified by firing at 1600°C for 6 h, and their thermal conductivity is 135 W . m −1. K −1 .The effect of Li 2 O addition on sintering and thermal conductivity also is discussed through thermo‐dynamic considerations.