Mn离子掺杂对0.7BiFeO₃-0.3BaTiO₃铁电陶瓷电性能影响

The Influence of Mn Ion Doping on the Electrical Properties of 0.7BiFeO₃-0.3BaTiO₃ Ferroelectric Ceramics

摘要: 0.7BiFeO₃-0.3BaTiO₃固溶体作为热门的反铁磁性和铁电性共存的多铁性功能材料，在固态制冷、电子通信等领域有着广阔的应用前景。但该材料固有的高漏导和低电阻率严重影响其实际应用。在众多离子掺杂调控缺陷化学行为改善电学性能的策略中，Mn元素具有多价态特性(Mn²⁺/Mn³⁺/Mn⁴⁺)展现出独特的优势，其掺杂可通过多重机制改善材料的电学性能。本工作我们采用固相反应法在0.7BFO-0.3BTO体系中引入MnO₂，研究了Mn离子引入对BFO-BTO固溶体相结构、介电、铁电的影响，并讨论了可能的机制。结果显示，0.7BiFeO₃-0.3BaTiO₃陶瓷结构为菱方相–赝立方相两相共存，随着MnO₂掺杂，XRD衍射峰向左偏移，发生晶格畸变。值得注意的是，BFO-BTO + xwt%MnO₂样品测试结果证明掺杂MnO₂能降低0.7BFO-0.3BTO陶瓷高温介电损耗，这是由于锰离子的掺杂有利于抑制氧空位的生成。另外，0.7BiFeO₃-0.3BaTiO₃ + 0.5wt%MnO₂陶瓷在120 kV/cm电场下的饱和极化强度达到51.04 μC/cm²，通过Mn离子掺杂导致0.7BiFeO₃-0.3BaTiO₃局部晶格畸变，诱导更强的饱和极化(P_s)，从而提高剩余极化强度(P_r)。最后，通过综合分析Mn离子引入对BFO-BTO + xwt%MnO₂陶瓷的各项电学性能影响，BFO-BTO + xwt%MnO₂陶瓷的高温极化强度增益情况为高温下氧空位对极化的屏蔽作用、畴壁的运动阻力降低和晶相结构变化三种机制协同作用的结果。

Abstract: The 0.7BiFeO₃-0.3BaTiO₃ solid solution, as a popular multiferromagnetic functional material with coexistence of antiferromagnetism and ferroelectricity, has broad application prospects in solid-state refrigeration, electronic communication and other fields. However, the inherent high leakage conductivity and low resistivity of this material seriously affect its practical application. Among numerous strategies for regulating the chemical behavior of defects through ion doping to improve electrical properties, the Mn element exhibits unique advantages due to its multivalent state characteristics (Mn²⁺/Mn³⁺/Mn⁴⁺), and its doping can enhance the electrical properties of materials through multiple mechanisms. In this work, we introduced MnO₂ into the 0.7BFO-0.3BTO system by solid-state reaction method. We studied the effects of Mn ion introduction on the bulk structure, dielectric and ferroelectricity of the BFO-BTO solid solution, and discussed the possible mechanisms. The results show that the ceramic structure of 0.7BiFeO₃-0.3BaTiO₃ is a coexistence of rhombohedral phase and pseudo-cubic phase. With the doping of MnO₂, the XRD diffraction peaks shift to the left, resulting in lattice distortion. It is worth noting that the test results of BFO-BTO + xwt%MnO₂ samples prove that doping MnO₂ can reduce the high-temperature dielectric loss of 0.7BFO-0.3BTO ceramics. This is because the doping of manganese ions is conducive to inhibiting the formation of oxygen vacancies. In addition, the saturation polarization intensity of 0.7BiFeO₃-0.3BaTiO₃ + 0.5wt%MnO₂ ceramics under a 120 kV/cm electric field reaches 51.04 μC/cm². The local lattice distortion of 0.7BiFeO₃-0.3BaTiO₃ is caused by Mn ion doping, inducing a stronger saturation polarization (P_s). Thereby improving the residual polarization intensity (P_r). Finally, through the comprehensive analysis of the influence of Mn ion introduction on various electrical properties of BFO-BTO + xwt%MnO₂ ceramics, the high-temperature polarization intensity gain of BFO-BTO + xwt%MnO₂ ceramics is the result of the synergistic effect of three mechanisms: the shielding effect of oxygen vacancies on polarization at high temperatures, the reduction of domain wall movement resistance, and the change of crystal phase structure.