Wei Jie, Wu Chunfang, Liu Yalong, Guo Yaxin, Yang Tiantian, Wang Dawei, Xu Zhuo, Haumont Raphael
Electronic Materials Research Laboratory, Key Laboratory of Ministry of Education & International Center for Dielectric Research, Xi'an Jiaotong University , Xi'an 710049, P. R. China.
Laboratoire de Physico-Chimie de l'Etat Solide, ICMMO, CNRS-UMR 8182, Bâtiment 410 -Université Paris-Sud XI , 15 rue Georges Clémenceau 91405 Orsay Cedex, France.
Inorg Chem. 2017 Aug 7;56(15):8964-8974. doi: 10.1021/acs.inorgchem.7b00914. Epub 2017 Jul 12.
Rare-earth ions (RE = La, Nd, and Er) substituted BiFeO (BFO) ceramics were synthesized by a conventional solid-state sintering procedure. X-ray diffraction patterns and Raman spectra confirm a rhombohedral R3c symmetry in all samples with significant distortion in FeO octahedron, as well as the occurrence of remarkable spin-phonon coupling and notable change in magnetic transition temperature induced by RE dopants. The enhanced magnetization was observed in all RE-doped BFO ceramics, unveiling that the spatial spin structure of BFO should be perturbed by RE dopants. Diffuse reflectance spectra show a conspicuous evolution of interband electronic transitions in RE-doped BFO ceramics. Especially, the two crystal-field d-d band transitions (A→T and A→T) exhibit a linear red-shift behavior with the reduction in the cell volume, which is well-linked with a linear tendency of increased magnetization. On the basis of these investigations, a possible mechanism was proposed in this paper to demonstrate the correlation between the structural distortion, interband electronic transitions, and magnetic properties in RE-doped BFO ceramics.
通过传统的固态烧结工艺合成了稀土离子（RE = La、Nd和Er）取代的BiFeO（BFO）陶瓷。X射线衍射图谱和拉曼光谱证实，所有样品均具有菱面体R3c对称性，FeO八面体存在明显畸变，同时出现了显著的自旋-声子耦合以及由稀土掺杂剂引起的磁转变温度的显著变化。在所有稀土掺杂的BFO陶瓷中均观察到了增强的磁化强度，这表明BFO的空间自旋结构应受到稀土掺杂剂的扰动。漫反射光谱显示了稀土掺杂BFO陶瓷中带间电子跃迁的显著演变。特别是，两个晶体场d-d带跃迁（A→T和A→T）随着晶胞体积的减小呈现出线性红移行为，这与磁化强度增加的线性趋势密切相关。基于这些研究，本文提出了一种可能的机制，以证明稀土掺杂BFO陶瓷中结构畸变、带间电子跃迁和磁性能之间的相关性。
