Size-controlled synthesis of BiFeO₃ nanoparticles by a soft-chemistry route

In this work we report the size-controlled synthesis of BiFeO₃ nanoparticles via a soft-chemistry route. In this route, the aqueous solution of inorganic Bi and Fe salt is gelled by using acrylamide and bisacrylamide. It is demonstrated that the grain size of resulted BiFeO₃ powders can be tailored by varying the ratio of acrylamide to bisacrylamide. With increase in the bisacrylamide content, the grain size decreases monotonously. By using this method, a series of BiFeO₃ samples with average grain size ranging from 110 to 52 nm have been prepared. The thermal decomposition process of precursor xerogels and the formation of BiFeO₃ phase are investigated by means of X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry analysis, and fourier transform infrared spectroscopy (FTIR). SEM observations reveal that the prepared BiFeO₃ nanoparticles are nearly spherical in shape with a narrow diameter distribution. Magnetic hysteresis loop measurement shows that the BiFeO₃ nanoparticles exhibit weak ferromagnetic behavior at room temperature, and a saturation magnetization of ~1.56 emu/g is achieved for the 52 nm sample.