双层钙钛矿氧化物BaLaM2O6-δ非常规轨道杂化诱导晶格畸变及其磁、电性质研究

项目名称： 双层钙钛矿氧化物BaLaM2O6-δ非常规轨道杂化诱导晶格畸变及其磁、电性质研究

项目编号： No.21661025

项目类型： 地区科学基金项目

立项/批准年度： 2017

项目学科： 数理科学和化学

项目作者： 白一甲

作者单位： 内蒙古工业大学

项目金额： 20万元

中文摘要： BaLaMn2O6-δ双层钙钛矿氧化物的A位阳离子具有层状有序结构。研究发现，通过引入二级姜-泰勒离子可诱发晶体结构的中心对称性缺失，从而使其表现出优异的磁、电性质。最近的理论研究表明，A位层状有序双钙的对称中心破缺可能与阴、阳离子间的价层电子轨道发生非常规的杂化行为有关。目前，国内外关于该体系的轨道非常规杂化的相关研究报道较少，因此在充分认识轨道非常规的杂化作用机制的基础上，开展针对该体系电子极化程度的精细调控十分必要。本项目一方面通过考察内禀离子分布因素和外源化学掺杂因素对目标体系结构非心对称性的影响程度，进而明确轨道非常规杂化、晶体中心对称性缺失、材料性质三者之间的构效关系；另一方面借助理论计算，构筑轨道非常规杂化的电子能带结构模型，建立合理阐述目标体系构效关系的微观物理图像。本项目的研究结论可为轻稀土陶瓷材料在分子尺度内的磁、电、光催化性能的精细调控提供有价值的实验和理论参考。

中文关键词： 双层钙钛矿氧化物；A位离子有序；非常规轨道杂化；磁-电耦合；铁电极化

英文摘要： The A-site cation layer ordering structure is confirmed in double-perovskite oxides (DPOs) BaLaMn2O6-δ. Research found that the noncentrosymmetric crystal structure could be stable via substituting second-order Jahn-Teller (SOJT) ions and rent this compound a supiror performance in magnetism and electron polarization. Recent theoretic studies have been reported that the absence of the symmetry center is probablely ascribed to the improper orbital hybridization (IOH) between the valence shell electrons from cation and anion. So far, based on the A-site ordering DPOs system, few studies related with IOH behavior in home and abroad are reported. Consequently, studies on finely tuning the degree of electron polarization by fully understanding the mechanism of IOH interaction are highly required. This project is performed in two parts. On one hand, investigating the impact extent of structural noncentrosymmetry by appling the intrinsic factor (cation arrangement) and the extrinsic factor (SOJT ion doping) and then clearifing the structure-activity mechanism above IOH, noncentrosymmetry and material properties; On the other hand, using theoretic calculation，constructing the model of electronic band structure for IOH and dipicting a reasonable microscopic physical image for interpreting the structure-activity relationship. The research conclutions is highly expected to provide an essential guidance for designing novel light rare-earth elements based functional ceramic material and for finely tuning the magnetic, electronic and photocatalytic properties in molecular scale.

英文关键词： double perovskite oxides;A-site cation ordering;improper orbital hybridization;magneto-electric coupling;ferroelectric polarization