Synthesis of AlN porous-shell hollow spheres by a combustion route

Aluminum nitride (AlN) porous-shell hollow spheres with diameters ranging from 2 to 3 μm and porous-shell thickness of about 120 nm were successfully prepared via a facile combustion synthesis route in the presence of polytetrafluoroethylene (PTFE), in which porous-shell was composed of a large number of irregular nanoparticles. These synthesized spheres were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) measurements. The possibility of the reactions of PTFE with Al particles was also investigated by thermogravimetry-differential scanning calorimetry (TG-DSC). It was found that PTFE was not only an active agent for the nitridation of Al particles, but also a structure-directing agent for the formation of this hollow structure. Based on the experimental results, a possible model for the growth of AlN porous-shell hollow spheres was proposed.