Mechanism of the formation of novel Al2-xHfxO3 materials via a combustion synthesis method

In this paper, the synthesis mechanism of novel hafnium-doped alumina, Al2-xHfxO3 (x ​= ​0.001, 0.002 and 0.003) materials have been successfully formed via a self-propagating combustion (SPC) method. In-depth study of the materials through characterization by simultaneous thermogravimetric analysis (STA), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy dispersive X-ray (EDX) were systematically done. STA technique were used to characterize the thermal profile of the precursors. From the analysis, the synthesis mechanism of the materials was proposed. XRD results reveal that hafnium doped materials correspond to the hexagonal crystal structure of Al2O3 that shows a success of the substitutional doping. The FESEM micrographs shown that the morphology of the materials was not significantly affected by the dopant concentrations. However, the presence of Hf4+ ions in Al2O3 were confirmed where the synthesized stoichiometry of all materials were perfectly identical to the obtained stoichiometry from EDX.