新型多铁性氧化物材料的设计合成及其机理研究

项目名称： 新型多铁性氧化物材料的设计合成及其机理研究

项目编号： No.91222107

项目类型： 重大研究计划

立项/批准年度： 2013

项目学科： 无机化学

项目作者： 孙俊良

作者单位： 北京大学

项目金额： 70万元

中文摘要： 多铁性材料通常指同时具有电极化有序和磁有序的材料， 这类材料在"磁读电写"和"多态存储"上有着很强的潜在应用。寻找能够在室温附近使用的多铁性化合物以及多铁性的形成机理一直是各国科学工作者不懈努力的目标。本课题中利用近年来发展起来一种新的合成方法-拓扑反应法来调控各种化合物的磁性和极化特性，从而提高磁有序温度和介电常数, 以期获得室温附近可使用的多铁性化合物。我们将通过各种表征手段（X射线衍射，中子衍射，电镜等）对其原子结构和电子结构，磁畴和电畴进行研究。由于特殊的合成方法，本课题中获得的新化合物结构相对可控，其磁电性质变化也更有迹可寻，这为研究多铁性的形成机理提供了很好的实验数据。在此基础上，本课题将通过理论计算深入理解多铁性化合物的结构和性质的关系，试图建立简单的多铁性质模型，从而指导新型材料的合成与改良。

中文关键词： 铁电；铁磁；非共度结构；氧化物；结构确定

英文摘要： Multiferroic materials, showing two or more ordering parameters such as ferroelectric, ferromagnetic, and ferroelastic ordering, have been extensively studied for potential applications in “magnetic reading and electric writing” and "multi-state information storage". It is the goal for many researchers to find the multiferroics which can be used at room temperature and the mechanism of the multiferroic behaviors. In this project, a newly developing synthesis method, the topotactic reaction method, will be used to adjust the magnetic and electrical properties of various compounds, which may improve the magnetic ordering temperature and dielectric constants of the compounds. Therefore, more multiferroic compounds, which can be potentially used at room temperature, are expected to be synthesized. X-ray, electron, and neutron diffraction methods will be used to analyze the crystal and electric structure of these compounds, the magnetic and electric domains of the corresponding materials. Owing to the specific synthesis method, the structure of the obtained new compounds is more controllable, and the changing of magnetic and electric properties of these compounds may be easy to be tracked and studied. Thus, more useful experimental data can be obtained for the understanding of the mechanism of the multiferroic behav

英文关键词： ferroelectricity；ferromagnetism；incommensurate structure；oxides；structure determination