Synthesis of an aluminum nitride–yttria (AlN–Y2O3) composite from nano-sized porous AlN and YCl3

In order to enhance the thermal conductivity of aluminum nitride (AlN) with sintering additives including yttria (Y 2 O 3 ), it is necessary to form yttrium aluminate garnet (YAG) and secondary phases both within and around the boundaries of AIN drains. Nano-sized porous AlN particles were produced to form YAG and secondary phases within AlN grains, after which a AlN–Y 2 O 3 nano–nano composite was formed from AlN and amorphous Y 2 O 3 . Porous AlN powders were first successfully synthesized by the chemical vapor synthesis (CVS) method. Highly crystalline and nano-sized porous AlN powders were synthesized at 1,200 °C. Brunauer–Emmett–Teller (BET) analysis showed that these powders had very large surface areas, suggesting that the particles approached nano-scale sizes with very small pores. To form composites of Y 2 O 3 and AlN, we prepared a yttrium source solution that infiltrated the nano-sized pores of the AlN particles. Such an infiltration of AlN with amorphous Y 2 O 3 was expected to effectively reduce the residual oxygen content by facilitating the formation of YAG and secondary phases during the sintering process. We characterized the composite powders of AlN–Y 2 O 3 and the sintered bodies using BET, XRD, SEM, TEM, and thermal conductivity analyses.