Morphology and optical absorption of Bi2Fe4O9 crystals via mineralizer-assisted hydrothermal synthesis

Submicron-sized Bi2Fe4O9 crystals were successfully synthesized via the hydrothermal method, while micron-sized Bi2Fe4O9 crystals with rod-like morphologies were obtained in the presence of the mineralizer KNO3. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were employed to characterize the products. According to a series of time-dependent experiments, it was concluded that the likeliest formation mechanism for the microrods was the Ostwald ripening process. It was proposed that the blocking effect of NO3- contributed to the formation of the rod-like powders. Moreover, the optical absorption of the prepared Bi2Fe4O9 crystals was measured using an UV-vis spectrophotometer, indicating that Bi2Fe4O9 powders can be used as effective photocatalysts under visible light. (C) 2012 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.