Effect of urea on the size and morphology of AlN nanoparticles synthesized from combustion synthesis precursors

AlN nanoparticles were synthesized by carbothermal reduction method using a combustion synthesis precursor derived from aluminum nitrate, glucose, and urea mixed solution. Effects of urea on the combustion temperature of solutions, the particle size and morphology of precursors, the intermediate formed γ-alumina, and the synthesized AlN were studied in detail. The results indicated that the homogeneous mixture of amorphous (Al2O3 + C) precursor might be prepared by selecting an optimum molar ratio of urea to aluminum nitrate (U/Al) in solution by combustion synthesis method. Furthermore, a regular variation in the particle size and morphology of precursors had been observed with increasing (U/Al). The nitridation products, synthesized at 1500 °C, retained the characteristics of γ-alumina in the precursors. The nitridation products, prepared with (U/Al = 0.5–2), comprised of well-distributed spherical particles of AlN with the average size ranging from 30 to 80 nm. Moreover, the nitridation reactivity of products with (U/Al = 0.5–2) had been found at 99%, which was significantly higher than that of the nitridation products prepared with (U/Al = 0.3, 2.5, 3) and without urea.