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Design of new material by control of the orbital phase transition

通过控制轨道相变设计新材料

基本信息

批准号：
11220207
负责人：
AKIMITSU Jun
金额：
$ 35.84万
依托单位：
Aoyama Gakuin University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

In order to reveal the various properties influenced by p and f electrons, this project has designed new functional materials by performing the research of systems including p and f electrons with "design of new material by controlling orbital phase transition" taken as purpose. In particular, the discovery of superconductivity in MgB_2 and elucidation of its fundamental properties was important results. It was cleared that the 2 dimensional sheet formed by B atoms in this material much contribute to the occurrence of superconductivity. Because of the charge transfer between ヲミ and ヲメ orbital at superconducting state, the charge density changed before and after superconducting transition from MEM/Rietveld analysis. Moreover, we concentrated our interest to the relationship between the superconductivity and the network formed by B atoms. From this point of view, we successfully discovered the superconductor Re_3B and Re_7B_3 in Re-B system and W_7Re_<13>B of which crystal structure was … More stabilized by B atoms and elucidated the fundamental properties of these new materials. It has not been possible to grow large single crystal and elucidate the physical properties using single crystal, however, the project has performed the pioneering role in the design of new material. Because the strong covalent bonding nature of B atoms that mediated by sp orbital control the physical properties in MgB_2, this material is extremely unique.On the other hand, we discovered the ferromagnetism in CaB_2C_2 with no magnetic elements. But we have not excluded the possibility that Fe impurities may play an important role and the influence by strong sample dependence. However, it was considered that the local distortion of crystal structure was related to magnetism in this material by the fine crystal structure analysis. More inspection is needed for supporting this result.For f electron systems, we have revealed the physical properties and the orbital ordering in CeB_6 and related materials. In particular, we have observed that magnetic moment in CeB_6 existed among Ce site. Less

为了揭示p、f电子对各种性能的影响，本课题以“通过控制轨道相变设计新材料”为目的，通过对包含p、f电子的体系进行研究，设计出新的功能材料。特别是MgB_2超导性的发现及其基本性质的阐明是重要的结果。结果表明，该材料中B原子形成的二维片层对超导电性的发生有重要贡献。从MEM/Rietveld分析可知，由于超导态下的电荷转移，超导转变前后的电荷密度发生了变化。此外，我们还对超导电性与B原子网络结构的关系进行了研究。从这一观点出发，我们成功地发现了Re-B系中的超导体Re_3B和Re_7B_3，<13>以及晶体结构为 ...更多信息由B原子稳定，并阐明了这些新材料的基本性质。虽然无法生长大单晶并使用单晶阐明物理性质，但该项目在新材料设计方面发挥了开创性作用。由于B原子以sp轨道为媒介的强共价键性质控制了MgB_2的物理性质，因此这种材料是非常独特的。但我们没有排除铁杂质可能起重要作用的可能性，以及强样品依赖性的影响。然而，通过精细晶体结构分析，认为晶体结构的局部畸变与该材料的磁性有关。对于f电子体系，我们揭示了CeB_6及其相关材料的物理性质和轨道有序性。特别地，我们观察到CeB_6的磁矩存在于Ce位之间。少