Synthesis of Fine AlN Powder by Vapor Phase Reaction of AlCl₃ and NH₃

Abstract

Fine AlN powder was synthesized by vapor phase reaction of AlCl₃ and NH₃ at 720°-1190°C. Most of the powder deposited separately in two regions in the reactor. The powder deposited in the range between the end of AlCl₃-feeding tube and the point 17cm apart there from consisted of one phase AlN. The particle size and its distribution became fine and uniform at high reaction temperature or at high total flow rate of NH₃ and N₂. Fine powder with the median diameter of 0.16μm was synthesized at 1190°C and particles were within a narrow range from 0.1 to 3.0μm. In the range between 20 and 33cm apart from the end of the AlCl₃-feeding tube, amorphous AlN deposited, which crystallized on heating at 1400°C. Byproduct, NH₄Cl which coexisted with amorphous AlN, was easily eliminated by heating at 500°C. The formation rate of crystalline AlN was 2.2g·h^-1 and the total yield of crystalline and amorphous AlN was 79%.