Ni掺杂对BiFeO3薄膜晶体结构和磁性的影响

Effect of Ni Doping on the Crystal Structure and Magnetic Properties of BiFeO3 Films

采用溶胶-凝胶法在Si/SiO2衬底上制备BiFeO3(BiFe1-xNixO3,x=0,0.05,0.10,0.15)薄膜。分别研究了Ni对BiFe1-xNixO3晶体结构、表面形貌、光学性能以及磁性的影响。X射线衍射光谱显示,Ni掺杂改变了BiFe1-xNixO3体系的晶体结构,由菱形相转变为正方相。扫描电子显微镜(SEM)显示,Ni掺杂可以提高BiFe1-xNixO3薄膜的结晶度。拉曼光谱表明纯BFO具有较强的振动峰,但随着Ni掺杂量的增加,拉曼峰发生了红移,这表明Ni掺杂缩短了BiFeO3薄膜中Bi-O原子间的距离。与BiFeO3薄膜相比,BiFe1-xNixO3(x=0.05,0.1,0.15)薄膜的饱和磁化强度(Ms)明显增强,说明Ni含量的增加导致了更多的结构畸变,从而抑制了BiFe1-xNixO3薄膜的自旋结构。研究结果可为信息存储提供潜在的应用。

The multiferroic BiFeO 3(BiFe1-xNixO3,x=0,0.05,0.10,and 0.15)films have been prepared on silicon substrates by the sol-gel method.The effects of Ni on BiFeO 3 crystal structure,surface morphology,optical properties and magnetic properties were investigated.X-ray diffraction spectra indicated that Ni substitution changed the crystal structure of the BiFe1-x NixO3 system from rhombohedral to tetragonal phase.Scanning electron microscopy(SEM)showed that Ni doping can improve the crystallinity of BiFe1-x NixO3 films.Raman spectra revealed that pure BFO have strong vibration peaks.However,with the increase of Ni doping,the Raman peaks was redshifted.The result indicated that Ni doping reduced the distance between Bi-O atoms in BiFeO 3 thin films.Compared with BiFeO 3 film,the saturation magnetization(M s)of BiFe1-x-NixO3(x=0.05,0.1 and 0.15)films was significantly enhanced,which indicated that the increase of Ni content inducing more structure distortion and thus suppressing cycloid spin structure in BiFe1-x NixO3 films.Our result may provide potential applications in information storage.