Ho掺杂对BiFeO_3介电、铁磁性及磁电耦合效应的影响

采用固相反应法制备出Bi1-xHoxFeO3(x=0,0.05,0.1,0.15,0.2)陶瓷样品,利用X射线衍射仪、精密阻抗分析仪和物性测量系统分别测试了样品的晶体结构、介电特性、磁滞回线并计算出了磁介电系数.结果表明:Ho掺杂量x≤0.1时,Bi1-xHoxFeO3样品呈现扭曲的三方钙钛矿结构,当x≥0.15时,Bi1-xHoxFeO3样品从三方晶系逐渐向正交晶系转变;当频率f=100Hz时,BFO-10%的介电常数是BiFeO3的3倍,且介电损耗相对减小.在f=10kHz,外加磁场为25 00Oe时,BiFeO3,BFO-10%的磁介电系数(MD)分别是-10.17%,-14.65%.在30kOe的磁场作用下,样品的磁滞回线随着掺杂量的增大而逐渐趋向饱和,其剩余磁化强度(Mr)从0.002 4emu/g(BFO)增加到0.116 7emu/g(BFO-20%),说明Ho掺杂显著增强了BFO的铁磁性.

Effect of Ho Doping on the Dielectric,Ferromagnetic and Magnetoelectric Coupling Properties of Multiferroic BiFeO3Ceramics

Multiferroic Bi1-xHoxFeO3(x=0,0.05,0.1,0.15,0.2)ceramics were prepared by solid state reaction.The crystalline structure,dielectric constants and hysteresis loops of all samples were characterized by using XRD,HP4294Aprecision impedance analyzer and VersaLab,respectively.The magnetodielectric coefficients were calculated,which reveals the magnetoelectric coupling effect of Bi1-xHoxFeO3.The results show that BFO ceramics have a rhombohedrally distorted perovskite structure when the doping level is less 0.15.BFO-10%has lower dielectric loss and three times larger dielectric constants than BFO at an applied electric field of 100Hz.When the doping level x≥0.15,a transformation from rhombohedral system to orthorhombic system has been detected in Bi1-x HoxFeO3.The magnetodielectric coefficient of BFOand BFO-10% is-10.17%and-14.65%respectively when f=10kHz and H=2 500Oe.The hysteresis loops of samples have a gradually saturated tendency with increasing of Ho content;the Mrincreased from 0.002 4emu/g for BFO to 0.116 7emu/g for BFO-20% with an applied maximum magnetic field of 30kOe.