多铁性BiFeO_3纳米颗粒的尺寸依赖磁性能研究

Study on the size-dependent magnetic properties of multiferroic BiFeO_3 nanoparticles

采用乙二胺四乙酸杂化溶胶法制备了不同晶粒尺寸的纯相BiFeO_3纳米颗粒,并利用X射线衍射仪、扫描电镜、超导量子干涉仪和Mossbauer谱系统研究了其结构、形貌以及磁性能.结果表明:BiFeO_3纳米颗粒具有明显的弱铁磁性,并呈现强烈的尺寸依赖特性;这种弱铁磁性主要源于纳米材料的尺寸限制效应,而非杂质相或Fe^(2+)的存在所致.

The pure phase BiFeO3 nanoparticles with different sizes are prepared by an ethylenediaminetetraacetic acid complexing sol-gel process. The structure, the morphology and the magnetic properties of BiFeO3 nanoparticles are characterized by X-ray diffractometry, scanning electron microscopy, superconducting quantum interference device magnetometer and Mossbaner spectra analysis. The results show that the BiFeO3 nanoparticle possesses an weak ferromagnetism at room temperature with a strongly size-dependent property. It reflects that the weak ferromagnetism present in the BiFeO3 nanoparticle should be attributed to the grain size-confinement effect, rather than the existence of the magnetic impurity or Fe2＋.