Ho掺杂对BiFeO_3介电、铁磁性及磁电耦合效应的影响

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

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.

Abstract： Multiferroic Bil-x Hox FeOa （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, HP4294A preci- sion impedance analyzer and VersaLab, respectively. The magnetodielectric coefficients were calculated, which reveals the magnetoelectric coupling effect of Bil-x HoxFeO3. The results show that BFO ceramics have a rhombohedrally distorted perovs- kite 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 100 Hz. When the doping level x≥0.15, a transformation from rhombohedral system to orthorhombic system has been detected in Bil-x HoxFeO3. The magnetodielectric coefficient of BFOand BFO- 10% is -10.17% and-14.65% respectively when f= 10 kHz and H= 2 500 Oe. The hysteresis loops of samples have a gradually sat- urated tendency with increasing of Ho content; the Mr increased from 0. 002 4 emu/g for BFO to 0. 116 7 emu/g for BFO- 20% with an applied maximum magnetic field of 30 kOe.