Is it possible to synthesize cubic aluminum nitride by the carbothermal reduction and nitridation method?

Abstract

In order to investigate whether it is possible to synthesize cubic AlN (c-AlN) by the carbothermal reduction and nitridation method, the products obtained by calcining a (hydroxo)(suberato)Al(III) complex under a flow of nitrogen in the temperature range of 1200–1600 °C were characterized by XRD and 27Al magic-angle spinning (MAS) NMR spectroscopy. The products consisted of wurtzite AlN (w-AlN), γ-Al 2O 3, α-Al 2O 3 and γ-aluminum oxynitride (γ-AlON). The two materials γ-AlON and c-AlN, which have very similar XRD patterns each other, were differentiated by their 27Al MAS NMR spectra. The 27Al MAS NMR spectra of the products showed no peak at the chemical shift of c-AlN, which was estimated by the correlation between the 27Al chemical shifts of AlX (X = P, As and Sb) in the cubic phase with the reciprocal of their band gaps. These results indicate that it is impossible to synthesize metastable c-AlN by the CRN method because of very high reaction temperature.