Development of electrical, magnetic, and optical novel properties by the emergence of spin and electric polarization fields

本研究基于物理、化学和材料加工的出现，致力于开发具有铁电性、铁磁性和发光性能的新型氧化物材料。(1)根据理论和实验结果，对位移型铁电材料的铁电性来源进行了详细的考察。我们可以成功地提出一种超越量子临界极限的量子顺电材料的新模型。(2)基于寻找具有四面体结构的新型铁电材料的项目，合成并详细研究了铁电材料Bi2SiO5。这种材料使我们相信，即使是SiO4四面体也可以变形为具有电极化。详细的结构分析表明，该材料属于铁电材料范畴。(3)可以得到只由O、Al、Fe等普遍存在的元素组成的新的多铁体。

This research has intended to develop novel oxide materials with ferroelectricity, ferromagnetism, and luminescent properties based on the emergence of the physics, chemistry, and materials processing. (1)Detailed inspections based on the theory and experimental results on the origin of the ferroelectricity in displacive-type ferroeloectrics. We could succeed in proposing a new model for quantum paraelectrics beyond the critical parameters for quantum critical limit.(2)Based on the project searching for new ferroelectric with tetrahedral structural copmpoiments, ferroelectric Bi2SiO5 was synthesized and investigated in detail. This material convinced us that even SiO4 tetrahedron can be deformed to have electric polarization. Detailed structural analysis revealed that this material belongs to a kind of ferrielectric category.(3)New multiferroiics composed of only ubiquitous elements such as O, Al, Fe could be obtained.