Combustion synthesis of porous bismuth oxide

Bismuth oxides with a micro porous structure were prepared by a simple combustion reaction between oxidizer (bismuth nitrate) and fuel (citric acid). These porous bismuth oxides were prepared at different values of the stoichiometric coefficient. The as-prepared products were characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results show that many pores distributed in tetragonal bismuth oxides (β-Bi2O3) granules which have varied crystallinity and particle sizes at different oxidizer/fuel ratio. Increasing the fuel concentration improved the crystallinity and purity of β-Bi2O3. A further calcination could also increase the particle size, crystallinity and transform the phase structure from β-Bi2O3 to pure α-Bi2O3.