Gd,Co共掺杂对BiFeO_3陶瓷电输运和铁磁特性的影响  

Effects of Gd and Co doping on the electrical and ferromagnetism properties of BiFeO_3 ceramics

作　　者：宋桂林[1,2] 周晓辉[1] 苏健[1] 杨海刚[1,2] 王天兴[1,2] 常方高[1,2] 

机构地区：[1]河南师范大学物理与信息工程学院,新乡453007 [2]河南省光伏材料重点实验室,新乡453007

出　　处：《物理学报》2012年第17期494-501,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:60571063);河南省重点科技攻关项目(批准号:122102210191);河南省教育厅自然科学研究计划(批准号:2011A140014);河南师范大学青年基金(批准号:2010qk02)资助的课题~~

摘　　要：采用快速液相烧结法制备BiFeO_3和Bi_(0.95)Gd_(0.05)Fe_(1-x)Co_xO_3(x=0,0.05,0.1,0.15,0.2)陶瓷样品,研究Gd,Co共掺杂对BiFeO_3微观结构,介电性能和铁磁性的影响.X射线衍射谱表明:所有样品的主衍射峰与纯相BiFeO_3相符合且具有良好的晶体结构,随着Co^(3+)掺杂量x的增大,Bi_(0.95)Gd_(0.05)Fe_(1-x)Co_xO_3样品的主衍射峰(104)与(110)逐渐相互重叠,当x大于0.1时,样品呈现正方晶系结构;J-V特性显示Gd3+,Co^(3+)共掺杂有效地降低BiFeO_3陶瓷的漏导电流,其降低幅度为1—2个数量级;当f=10~3 Hz时,Bi_(0.95)Gd_(0.05)Fe_(0.8)Co_(0.2)O_3的介电常数是BiFeO_3的6倍,而Bi_(0.95)Gd_(0.05)Fe_(0.95)Co_(0.05)O_3和Bi_(0.95)Gd_(0.05)Fe_(0.85)Co_(0.15)O_3样品的介电损耗最小,均为0.01.室温下,Bi_(0.95)Gd_(0.05)Fe_(1-x)Co_xO_3样品磁性与BiFeO_3相比显著增强.在磁场为30 kOe的作用下,Bi_(0.95)Gd_(0.05)Fe_(1-x)Co_xO_3(x=0,0.05,0.1,0.15,0.2)的剩余磁化强度M_r分别是BiFeO_3的34,60,105,103,180倍.样品磁性增强的主要原因是Gd,Co掺杂使BiFeO_3的晶格结构发生变化导致BiFeO_3自身储存的磁性能被释放,Gd^(3+)的4f电子与Fe^(3+)或Co^(3+)的3d电子自旋相互作用及样品中存在局域的Fe-O-Co磁耦合三者共同作用的结果.Multiferroic Bi0.95Gd0.05Fe1-xCoxO3 （x= 0, 0.05, 0.1, 0.15, 0.2） ceramics were prepared by rapid liquid phase sintering method. We studied effect of Gd and Co doping on the structure, electrical and ferromagnetism properties of BiFeO3 ceramics. The structure and morphology of BiFeO3 ceramics are characterized by X-ray diffraction （XRD）. The results show that all the peaks for Bi0.95Gd0.05Fe1-xCoxO3 （x= 0, 0.05, 0.1, 0.15, 0.2） samples can be indexed according to the crystal structure of pure BiFeO3. And X-ray diffraction analysis reveals a phase transition in Gd-Co codoped BiFeO3 ceramics when x is larger than 0.1. The current densities of all samples measured at room temperature are approximately three orders of magnitude lower than that of BFO ceramic, and the leakage current of the ceramics at room temperature exhibits two distinctive conduction behaviors： Ohmic conduction and space charge limited （SCL） conduction mechanism. For all the samples studied here, the dielectric constant and dielectric loss decrease with the increase of frequency in a range from 1 kHz to 1 MHz. The dielectric constants of Bi0.95Gd0.05Fe1-xCoxO3 （x= 0, 0.05, 0.1, 0.15,0.2） samples are nearly 1.9, 2.68, 3.85, 5.3, and 6 times larger than that of pure BiFeO3 （εr= 61.2） ceramic at 1 kHz, respectively. And the dielectric losses of Bi0.95Gd0.05Fe1-xCoxO3 samples become smaller than that of BFO ceramic. The magnetic measurements show that all the samples possess strong ferromagnetism at room temperature expect BiFeO3 and Bi0.95Gd0.05FeO3 which are weakly ferromagnetic. Under an external magnetic field of 30 kOe, the values of Mr of Bi0.95Gd0.05Fe1-xCoxO3 are 34, 60, 105, 103 and 180 times that of BiFeO3, respectively.

关 键 词：铁磁电材料 磁滞回线 漏导电流 

分 类 号：O482.5[理学—固体物理]