中文摘要：

为了研究镧和锶共掺对铁酸铋纳米颗粒结构和物性的影响，通过溶胶-凝胶法制备了镧和锶共掺的铁酸铋纳米颗粒La_0.1Bi_0.9-Sr_xFeO_y（x=0，0．2，04）．通过X线衍射、透射电子显微镜、紫外-可见吸收光谱测试、漏电流和介电性能测试以及磁滞回线测试对样品的晶体结构、微观形貌、光学性能、电学性能和磁学性能进行表征．实验结果表明：随着锶含量的增加，样品的晶体结构从扭曲的菱方钙钛矿结构向四方结构转化，且样品的平均颗粒尺寸大幅度减小，从180nm减少到50nm．随着锶掺杂量的增多，样品的带隙值从2．08eV减小到1．94eV；同时，LBSF纳米颗粒的导电性明显增加，使LBSF样品从绝缘体过渡为半导体．此外，随着锶含量的增加，样品的饱和磁化强度也大幅度提高．由实验结果可知，镧和锶共同掺杂可以获得铁酸铋基的纯相多铁性材料，同时可以有效调节其电导率和磁性．

英文摘要：

In order to study the effects of La and Sr co-doping on structure and properties of BiFeO_3, nanoparticles （NPs） La_0.1Bi_0.9-xSr_xFeO_y （x = 0, 0.2, 0.4） were synthesized by sol-gel method. The crystalline structure, microstructural properties, optical properties, electrical properties and magnetic properties of the NPs were investigated by X-ray xdiffraction, transmission electron microscope, UV-vis absorption spectrum, the leakage current curve, the dielectric properties and the M-H curve, respectively. Experimental results show that with the content of Sr increasing, a systematic change in crystal structure from rhombohedral structure to tetragonal structure, and the particle size reducing from 180 nm to 50 nm. It is found that the Srdopant increasing effectively narrows the band gap from 2.08 eV to 1.94 eV, meanwhile it leads to an apparent enhancement in electrical conductivity of LBSF NPs, making a transition from insulator to semiconductor. In addition, the saturation mag- netization of the samples significantly increases with the Sr concentration increasing. The results suggest an effective avenue to modulate the conductivity and magnetic properties of BiFeO_3-based multiferroic materials with pure phase structure by co-doping with La and Sr.