Sm^(3+)和Co^(3+)共掺杂对BiFeO_3多晶陶瓷介电特性的影响  

EFFECTS OF Sm^(3+) AND Co^(3+) CO-DOPING ON DIELECTRIC PROPERTIES OF BiFeO_3 POLYCRYSTALLINE CERAMICS

作　　者：宋桂林[1,2] 杨海刚[1,2] 王昕[1] 杜丽军[1] 王晶晶[1] 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 [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》2010年第12期2262-2267,共6页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(60571063);河南省重大科技攻关(092102-210018);大学生科技创新(81047604);河南师范大学青年科研基金(01026400017)资助项目

摘　　要：用快速液相烧结法制备Bi0.95Sm0.05Fe1-xCoxO3(x=0,0.05,0.1)陶瓷样品,用X射线衍射仪分析样品结构,用HP4294A型阻抗分析仪分别测量系列样品的介电特性及相对介电常数(εr)随频率(f)的变化。结果表明:掺杂样品主衍射峰与纯BiFeO3相吻合且具有良好的晶体结构;随着Sm3+、Co3+引入,测量频率在1kHz～1MHz,所有样品的εr和介电损耗(tanδ)随测量f的增加而减少,f=10kHz时,Bi0.95Sm0.05FeO3的εr是BiFeO3的40倍。样品的εr、tanδ随Sm3+和Co3+掺量的变化可以在空间电荷限制电流理论框架下进行解释。样品的磁电耦合效应(Me)随磁场、Co3+掺量的增加而增大,其原因系Sm3+与Fe3+或Co3+通过交换相互作用使铁电极化矢量增大所致,其中Bi0.95Sm0.05Fe0.95Co0.05O3呈现较强的磁电耦合效应,其Me在8kOe(1Oe=79.5A/m)磁场的作用下已达到4.2%。Multiferroic Bi0.95Sm0.05Fe1-xCoxO3（x = 0,0.05,0.1） ceramics were prepared by the rapid liquid phase sintering method.The crystalline structures of all samples were characterized using the X-ray diffraction.Frequency dependence of dielectric properties of all samples was measured with an HP4294A precision impedance analyzer.All peaks for Bi0.95Sm0.05Fe1-xCoxO3 samples can be indexed according to crystal structure of pure BiFeO3.For all samples studied,relative dielectric constant（εr） and dielectric loss（tan δ） decrease with increasing frequency from 1 kHz to 1 MHz.At 10 kHz,the εr of Bi0.95Sm0.05FeO3 is about forty times of pure BiFeO3.The significant change in the dielectric properties of all Bi0.95Sm0.05Fe1-xCoxO3 samples may be understood in terms of space charge limited conduction associated with crystal defects.This is evidenced by increase of magnetoelectric coupling effect（Me） with Co3＋ doping and applied magnetic field.Ferroelectric polarization enhancement is attributed to the exchange interaction between the Sm3＋ and Fe3＋ or Co3＋.For Bi0.95Sm0.05Fe0.95Co0.05O3 at room temperature,Me = 4.2% at 10 kHz with a 8 kOe（1 Oe = 79.5 A/m） magnetic field.

关 键 词：铁磁电材料 介电特性 空间电荷 

分 类 号：O469[理学—凝聚态物理]