Factors controlling pure-phase magnetic BiFeO 3 powders synthesized by solution combustion synthesis

Abstract

Bismuth ferric oxide nanopowders were prepared through combustion method. Pure phase and well-crystallized BiFeO 3 can be obtained by controlling the combustion process, fuel type and fuel-to-oxidant ratio. The evolutions of phase constitution and structural characteristics of the as-resulted nanopowders were investigated by X-ray diffraction, scanning electron microscope, and simultaneous thermogravimetric analysis. The results revealed that both the type and amount of fuel have to be carefully considered because they play an important role in total reaction characteristics. Among all tested fuels, l-α-alanine and glycine are the suitable fuels for BiFeO 3 synthesis. For α-alanine, the optimal fuel-to-oxidant ratio is 0.22, which results in a suitable flame temperature for BiFeO 3 formation. Still, too little fuel would result in only amorphous phase powders due to the low flame temperature and too much fuel would lead to transformation of the BiFeO 3 phase to impurities because of the high flame temperature involved. The resulting BiFeO 3 nanopowders exhibited strong H 2O 2-activiting ability and weak magnetism. When BiFeO 3 nanopowders were used as a heterogeneous Fenton-like catalyst to degrade rhodamine B (RhB), the apparent rate constant for RhB degradation in the presence of H 2O 2 at pH 5.0 was evaluated to be 0.048 min −1.