Ca^(2+)掺杂对BiFeO_3陶瓷结构和磁、介电性能的影响  

Effect of Ca^(2+) Substitution On Structure, Magnetic and Dielectric Properties of BiFeO_3 Ceramics

作　　者：苏健[1,2] 张娜[1,2] 宋桂林[1,2] 周晓辉[1] 常方高[1,2] 

机构地区：[1]河南师范大学物理电子工程学院,河南新乡453007 [2]河南省光伏材料重点实验室,河南新乡453007

出　　处：《硅酸盐学报》2013年第9期1185-1191,共7页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(60571063);河南省重点科技攻关项目(122102210191);河南省基础与前沿技术研究计划项目(22300410231)资助

摘　　要：以Bi(NO3)3·5H2O、Fe(NO3)3·9H2O和Ca(NO3)2·4H2O为原料、乙二醇甲醚为溶剂、柠檬酸为络合剂,采用溶胶–凝胶法制备Bi1–x Cax FeO3(x=0、0.05、0.10、0.15、0.20)陶瓷样品。结果表明:所有样品的主衍射峰与纯相BiFeO3相吻合,样品晶粒尺寸随Ca2+掺杂量的增加而减小,在室温下各样品均具有完整的磁滞回线,样品铁磁性显著提高。当x=0.10时,剩余比磁化强度达到最大值(0.11A·m2/kg)。在外加磁场为398 kA/m时,样品的比磁化强度在644 K附近出现明显的反铁磁相变,反铁磁相变温度TN随掺杂量的增加而升高。在300~900 K,样品顺磁相变温度TP,以及TN和TP处比磁化强度的差值随Ca2+的增加均呈现先上升,在x=0.10时达到最大值,之后又呈下降趋势。样品在850K时比磁化强度出现明显变化,变化幅度随Ca2+掺杂量的增加而减小,在x=0.10时最小,之后又增大。不同磁场下样品剩余比磁化强度随温度变化表明:Bi1–x Cax FeO3陶瓷样品存在变磁性,当x=0.10时,变磁性最为明显。磁电耦合效应观测结果表明:样品的磁电耦合系数为负值,介电常数随外磁场变化反应灵敏,在x=0.10时磁电耦合效应为–14.2%,是纯相BiFeO3(其磁电耦合效应为–5%)的近3倍,表明掺杂适量Ca2+可增强样品的磁电耦合性能。Ca-doped BiFeO3 polycrystalline ceramics were synthesized by a sol-gel method with Bi（NO3）3·5H2O, Fe（NO3）3, 9H2OCa（NO3）2？4H2O as starting materials, glycol ether as a solvent and citric acid as a complexing agent. The results show that Bi1-xCaxFeO3 （x=0, 0.05, 0.10, 0.15 and 0.20） ceramics are well-crystallized. The grain size of Bi1-xCaxFeO3 ceramic decreases with increasing Ca2＋doping content. The magnetic hysteresis loops appear in all Ca-substituted specimens and the magnetization is greatly improved to the maximum value of 0.11 A·m2/kg at the doping content （x） of 0.10. The antiferromagnetic phase transition temperature （TN） as a distinct peak in the temperature-dependent specific magnetization curve of BiFeO3 increases with increasing Ca-doping con-tent. The paramagnetic phase transition temperature （TP）, and the difference between the specific magnetizations at TN and TP increase with increasing Ca2＋ doping content, and reach the maximum values when x=0.10. According to the magnetic measurements, the metamagnetism in Bi1-xCaxFeO3 samples exists and becomes the most intensive when x=0.10. The magnetoelectric coupling coeffi-cient of Bi1-xCaxFeO3 ceramics is enhanced and is nearly three times greater than that of pure phase BiFeO3 in the Bi0.9Ca0.1FeO3 compound. It is suggested that Ca doping could be an effective way to optimize the magnetic and magnetoelectric coupling perform-ance of BiFeO3.

关 键 词：多铁材料 铁酸铋 反铁磁相变 变磁性 磁电耦合 

分 类 号：O469[理学—凝聚态物理]