摘要:
利用传统的固相反应法制备了BiFe_（1-x）Mn_xO_3（x=0-0.20）陶瓷样品,研究了不同Mn~（4＋）掺杂量对BiFeO_3陶瓷密度、物相结构、显微形貌、介电性能和铁电性能的影响.实验结果表明：所制备的BiFe_（1-x）Mn_xO_3陶瓷样品的钙钛矿主相均已形成,具有良好的晶体结构,且在掺杂量x=0.05附近开始出现结构相变.随着Mn~（4＋）添加量的增加,体系的相结构有从菱方钙钛矿向斜方转变的趋势,且样品电容率大幅度增大,而介电损耗也略有增加;在测试频率为10~4Hz条件下,BiFe_（0.85）Mn_（0.15）O_3（ε_r=1065）的ε_r是纯BiFeO_3（ε_r=50.6）的22倍;掺杂后样品的铁电极化性能均有不同程度的提高,可能是由于Mn~（4＋）稳定性优于Fe~（3＋）,高价位Mn~（4＋）进行B位替代改性BiFeO_3陶瓷,能减少Bia＋挥发,抑制Fe~（3＋）价态波动,从而降低氧空位浓度,减小样品的电导和漏电流.
Abstract:
Multiferroic BiFe_（1-x）Mn_xO_3（x = 0,0.05,0.10,0.15,0.20）（represented as BF_（1-x）M_xO） ceramics are prepared by the conventional solid state reaction technique.The effects of Mn~（4＋） doping on density,phase structure,morphology,dielectric and ferroelectric properties are investigated.The X-ray diffraction patterns of the samples indicate that the typical perovskite phase structure of BiFeO_3 is formed,and a phase transition starts near x=0.05,i.e.,the phase structure is distorted from rhombohedral to orthorhombic by Mn~（4＋） doping.The dielectric susceptibility of the sample is significantly increased and the dielectric loss is slightly increased with the increase of Mn~（4＋） content.The dielectric constantε_r of the BiFe_（0.15）Mn_（0.15）O_3 ceramic at 10 kHz is as high as 1065,22 times larger than that for pure BiFeO_3 It is suggested by hysteresis loop measurements that the ferroelectric property of the BF_（1-x）M_xO ceramics is improved and the remanent polarization is increased by Mn~（4＋） doping.This is probably because Mn~（4＋） is more stable than Fe~（3＋）, and the B-site doping with higher valent Mn~（4＋） could reduce the volatilization of Bi~（3＋） and suppress the valence fluctuation of Fe~（3＋）, thereby reducing the concentration of oxygen vacancies and the leakage current in the ceramic.
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