Effect of aluminum source on the synthesis of AlN powders from combustion synthesis precursors

In the present work, the carbothermal reduction method was employed to fabricate the AlN powders by utilizing the combustion synthesized precursor derived from the mixed solution comprised of an aluminum source (Al(NO3)3 or Al2(SO4)3 or AlCl3), glucose, nitric acid, and urea. Effects of aluminum source on the particle size and morphology of precursors as well as synthesized AlN powders were studied in detail. The size and morphology of precursors, derived from various aluminum sources, had exhibited significant differences. The precursor from Al(NO3)3 source had completed the nitridation reaction at 1500 °C in 2 h. However, the nitridation reactions of the precursors from Al2(SO4)3 or AlCl3 source furnished at increased temperature of 1550 °C in 2 h. Moreover, the AlN powders from various aluminum sources have been synthesized directly from γ-Al2O3 without γ-Al2O3 to α-Al2O3 phase transition. The AlN powders from Al(NO3)3, calcined at 1550 °C for 2 h, were comprised of well-distributed spherical particles with an average size of 80 nm. While the AlN powders from AlCl3 or Al2(SO4)3 consisted of heterogeneously distributed spherical particles ranging from 100 to 200 nm or from 80 to 150 nm, respectively.