Thermal conductivity of AlN ceramics sintered with CaF2 and YF3

Abstract Dense AlN ceramics with a thermal conductivity of 180W/m·K were obtained at the sintering temperature of 1750 °C using CaF 2 and YF 3 as additives. At temperatures below 1650 °C, the shrinkage of AlN ceramics is promoted by liquid (Ca,Y)F 2 and Ca 12 Al 14 O 32 F 2 . Liquid CaYAlO 4 mainly improves the densification of the sample when the sintering temperature increases to 1750 °C. The formation of liquid (Ca,Y)F 2 at a relatively low temperature results in homogeneous YF 3 distribution around the AlN particles, which benefits the removal of oxygen impurity in the AlN lattice, and thus a higher thermal conductivity.