Synthesis and characterization of nanoparticles of wurtzite aluminum nitride from various nut shells

Nanoparticles of Aluminum Nitride (AlN) were synthesized from a thermal treatment of mixtures of aluminum oxide (Al2O3) and either shells of almond, cashew, coconuts, pistachio, or walnuts in a nitrogen atmosphere at temperatures in excess of 1450 °C. By selecting the appropriate ratios of each nutshell powder to Al2O3, it is demonstrated that stoichiometric aluminum nitride is produced via carbo-thermal reduction in nitrogen atmosphere. In addition, results show the formation of Al from Al2O3 before transformation to AlN. On the other hand, when Al was mixed with nutshell powder first, mixed phases of AlN and Al4C3 were formed before complete transformation to AlN. X-ray diffraction analysis, Raman scattering and Fourier Transform Infrared spectroscopy confirmed the wurtzite phase of aluminum nitride. Transmission electron microscopy indicated the formation of AlN nanoparticles. The formation of AlN from nutshells offers a simple route and avoids multiple-step processes involving carbon rich agents at elevated temperatures.