Reaction mechanisms of nano-sized AlN powders synthesized from dicyandiamide and its optical property

Abstract

Nano-sized AlN powders were successfully synthesized using a wet chemical route, with dicyandiamide as the nitrogen source reagent. The influence of dicyandiamide/metal precursor molar ratio on the purity, crystallization, microstructure, and optical properties of the calcined powders were studied. The underlying reaction mechanisms, along with the intermediates formed during the reactions, were also investigated. The compositions and morphologies of the as-received and prepared powders were subsequently characterized using XPS, FTIR, XRD, SEM, and TEM. The optical properties of the prepared powders were measured by ultraviolet–visible spectroscopy (UV–Vis). The precursor components decompose, and follow a complex reaction sequence as a function of temperature, finally leading to AlN formation at 800 °C. Increasing AlN content is achieved between 800 and 890 °C. Essentially only AlN arises following calcination at 900 °C. The AlN crystallite size and degree of crystallization further increase when calcining at 1000 °C. This work demonstrates a promising route to produce nano-sized AlN powders with favorable microstructures and optical properties.