A transmission electron microscopy study of submicrometer BiFeO3 particle prepared by an improved solid state reaction

In this work, submicrometer bismuth ferrite (BiFeO₃) particles have been prepared at the temperature of 750 °C by the improved solid state reaction, in which the quick sintering step is crucial in obtaining pure perovskite phase. The X-ray diffractometer (XRD) analysis indicates that the obtained BiFeO₃ particles are rhombohedral structure, and the refined cell parameters are a=5.622Å and α=59.355° (R=8.35%), similar to the reported data (JCPDS Card 86-1518, a=5.632Å and α=59.356°). The microstructure has been observed using transmission electron microscope (TEM), and the image shows that BiFeO₃ powders have the quasi spherical morphology with the mean particle size between 100-150nm. Further, the distinct lattice fringes reveal the nature of the single-crystalline BiFeO₃ nanostructure, and the interplanar spacing is about 0.87nm, corresponding well to the double spacing of (012). Moreover, it is interesting to note that there existed the dislocation in BiFeO₃ particle, which is believed to arise from the collision of different grains in growing process. The sintered compact bodies from BiFeO₃ fine particles show the slim ferroelectric loops, and dielectric properties are frequency independent. The measured dielectric constant and loss tangent are 19.5 and 0.0025 at room temperature, showing the potential application in multiferroic devices.