Bismuth ferrite (BFO), one of very few multiferroics with simultaneous coexistence of ferroelectric and magnetic ordering, has attracted much attention due to its potential applications for new memory devices. In this work, 30~90 nm BFO powders with single rhombohedral phase were prepared by chemical coprecipitation method and after calcining of 500oC. Photocatalytic properties of the powders and dielectric properties of BFO ceramic were characterized, respectively. Cut-off wavelength of the powders at 590 nm exhibited efficient ultraviolet photocatalytic activity, which has been demonstrated by a photocatalytic result. 0.3g BFO powders can make 10 ppm RhB aqueous solution (100 ml) to decolorize and RhB decomposition rate reached to 95% during 3 hr UV irradiation. BFO ceramic can be obtained by sintering the green disc compacted with BFO powders at 800oC for 1h. Its dielectric constant is t about 250, and its dielectric loss is 0.03 at below 100 oC in the frequency range of 102 ~ 104 Hz and up to 1200 at 200 oC under 1 kHz, respectively. Reduced polarization is found due to higher loss and lower dielectric constant of the ceramic when the measuing frequency is more than 104 Hz. Magnetic hysteresis loop of BFO ceramic also shows weaker magnetic property, which may be attributed to size confinement effect of the nanostructures.
Influence of Compacting Pressure on the Dielectric Properties of La-modified Bismuth Ferrite Multiferroics Prepared by Rapid Liquid-phase Sintering Method