Low temperature synthesis of aluminum nitride from anhydrous aluminum chloride-organic amine complex

Abstract

AlN was succeeded to be synthesized at a low temperature of 900–1000 °C from the anhydrous aluminum chloride-melamine complex of a ratio of 1 to 3. To synthesize AlN at low temperature, four complexes were made from the anhydrous aluminum chloride with melamine, urea, hexamethylenetetramine, and aniline as ligands. The coordination state of the complex was confirmed by Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). For the Al2p XPS spectra, a peak with higher binding energy emerged in the complex with melamine than the other complexes. For the N1s XPS spectra, the main peak with higher binding energy also can be detected, which indicates coordinated N to the Al atom. Consequently, the complex of AlCl₃ and three equivalents melamine showed a better coordination state than the others by FT-IR and XPS spectra. X-ray diffraction (XRD) patterns confirmed that the AlN phase forms for AlCl₃-equivalent melamine, -three equivalents melamine, and -three equivalents urea complex by heating at a low temperature of 900 and 1000 °C. Especially AlCl₃-three equivalents melamine complex can be converted to the AlN with relatively high crystallinity and fewer impurities due to its strong Al–N bonding on the triazine ring. The excess melamine due to the three equivalent amounts may work as reserve one which can provide to prevent a lack of melamine at high temperatures during AlN formation.