钙钛矿型复合铁氧体La_(1-x)Pb_xFeO_3纳米颗粒体系的结构研究

Structure of the Perovskite- type Complex Ferrites La_(1- x)Pb_xFeO_3 Nanoparticles

采用溶胶凝胶法成功制备了La1-xPbxFe O3(x=0,0.15,0.33)和不同颗粒尺寸的La0.67Pb0.33Fe O3纳米颗粒.通过X射线衍射和Rietveld法对所有样品的晶体结构进行了系统研究.结果发现,所有样品均具有正交钙钛矿结构,空间群为D162h-Pbnm,La3+(Pb2+)和O2-离子都偏离了理想的立方钙钛矿结构中的位置,围绕着Fe离子的氧八面体发生畸变.Pb含量和颗粒尺寸的增加,均导致Fe-O键长减小,Fe-O-Fe键角增加.

La1-xPbxFeO3（x=0.0.15 and 0.33） nanoparticles and La0.67Pb0.33FeO3 nanoparticles with different particle sizes were prepared by a sol-gel method. Crystal structure was checked by X-ray diffraction and refined by Rietveld method. The results indicate that all samples crystallized in orthorhombic structure and with the space group of D162h-Pbnm, The La3＋（ Pb2＋） ions and O2-ions are displaced from the ideal cubic positions. The oxygen octahedral surrounding the Fe ions are distorted. Both the increasing Pb level and the increasing particle size result in a decrease in Fe-O bond length and an increase in Fe-O-Fe bond angle.