Synthesis of aluminum nitride by a modified carbothermal reduction and nitridation method using basic dicarboxylate Al(III) complexes Al(OH)(Cn+2H2nO4)center dot xH(2)O (n=3, 6, 8)

Aluminum nitride (AIN) particles and whiskers were synthesized by using bas ic dicarboxylate Pl(III) complexes AI(OH)(Cn+2H2nO4). xH(2)O (n = 3, 6, 8) as a precursor. AIN was obtained by calcining the glutarate complex (n = 3, AG) without further additions of carbon source under flowing nitrogen in t he temperature range 1200-1500 degreesC and then burning out the residual c arbon. In contrast, for suberate (n = 6, ASu) and sebacate (n = 8, ASe) com plexes additional carbon was required for their complete conversion to AIN. The process of conversion of AG to AlN was investigated by Al-27 magic-ang le spinning (MAS) nuclear magnetic resonance, infrared spectroscopy, and X- ray diffraction. The complex began to decompose at ca. 400 degreesC and the n turned into gamma -alumina at temperature above 600 degreesC. Finally, th e gamma -alumina was converted to AIN without gamma-alpha alumina phase tra nsformation. The morphology of AIN powders was very similar to that of the precursor, indicating that conversion of alumina to AIN during the carbothe rmal reduction and nitridation does not proceed through gaseous intermediat es but through solid-state Al-oxynitride compounds. The AIN powders obtaine d consisted of ultrafine particles or mixtures of particles and whiskers. ( C) 2000 Elsevier Science Ltd. All rights reserved.