Accurate structure analyses of fullerene compounds by the Maximum Entropy Method

利用最大熵法准确分析富勒烯化合物的结构

• 批准号: 08405003
• 负责人: SAKATA Makoto
• 金额: $ 27.58万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08405003/
• 关键词: endohedral metallo-fullerene; Sc@CィイD282ィエD2; ScィイD22ィエD2@CィイD284ィエD2; Maximum Entropy Method; charge density; alkalidope fullerene; fullerene; accurate structure; Sc@C82; La@C82; マキシマムエントロピー法; 粉末回折; Y@C_<82>; Sc_2@C_<84>; マキシマムエントロビ-法; Y@C

There are three aims of this study. They are 1) to establish the accurate structure analytical method for fullerene compounds, 2) to find out the accurate structure of endohedral metallo-fullerene compounds at electron level and 3) to have better understanding of the relationships between superconductivity of alkalidope fullerene compounds and their structural characteristic. First of all, it was found out that the combination of Rietveld refinements and the Maximum Entropy Method (RietveldMEM) was a very powerful method to determine accurate charge density distribution of fullerene compounds. For example, it can allow flexibility of structural varieties sometimes occurred in fullerene compounds ; such as hemispherical distribution of a single atom. By using RietveldMEM, accurate electron density distributions were obtained for Sc@CィイD282ィエD2, ScィイD22ィエD2@CィイD284ィエD2, ScィイD23ィエD2@CィイD282ィエD2 and some others. The most surprising result was that encapsulated three Sc atoms formed triangular cluster in ScィイD23ィエD2@CィイD282ィエD2. For alkalidope fullerene, it was found out that there was clear relationship between charge transfer and transition temperature to superconductors, Tc, that is as charge transfer to fullerene cage increased, Tc increased.

这项研究有三个目的。 1）建立富勒烯化合物的精确结构分析方法；2）在电子水平上找出内嵌金属富勒烯化合物的精确结构；3）更好地理解碱金属富勒烯化合物的超导性与其结构特征之间的关系。首先，人们发现，Rietveld 改进和最大熵方法 (RietveldMEM) 的结合是一种非常强大的方法，可以确定富勒烯化合物的精确电荷密度分布。例如，它可以允许富勒烯化合物中有时出现的结构变化的灵活性；例如单个原子的半球形分布。通过使用RietveldMEM，获得了Sc@CィイD282ィエD2、ScィイD22ィエD2@CィイD284ィエD2、ScィイD23ィエD2@CィイD282ィエD2等的精确电子密度分布。最令人惊讶的结果是，SciiD23ィエD2@CィイD282ィエD2中封装了三个Sc原子，形成了三角形簇。对于碱掺杂富勒烯，发现电荷转移和向超导体的转变温度Tc之间存在明显的关系，即随着向富勒烯笼的电荷转移增加，Tc增加。

项目成果

M.Sakata他: "Charge Density of Hexagonal Boron Nitride Using Synchrotron Radiation Powder Data by Maximum Entropy." J.Phys.Chem Solids. Vol.58,. 177-183 (1997)

M. Sakata 等人：“通过最大熵计算六方氮化硼的电荷密度”。J.Phys.Chem Solids，第 58 卷（1997 年）。

M. Kanada他: "High Pressure Neutron and X-Ray Studies on the Mott Transition of BaCoS_2"J. Phys. Chemistry Sol.. 60・8-9. 1181-1183 (1999)

M. Kanada 等：“BaCoS_2 莫特跃迁的高压中子和 X 射线研究”J. Phys. Chemistry Sol. 60・8-9 (1999)。

M.Takata他: "Direct Observation of Pr-CuO_2 Hybridization in PrBa_2Cu_3O_<7-8> by the MEM Charge Density Study." Physica C,. 263,. 340-343 (1996)

M. Takata 等人：“通过 MEM 电荷密度研究直接观察 PrBa_2Cu_3O_<7-8> 中的 Pr-CuO_2 杂交”，263，340-343。

M. Takata他: "Direct Observation of Orbita 1Orderin Manganites by MEM Charge-Density Study"J. Phys. Soc. Jpn.. 68・7. 2190-2193 (1999)

M. Takata 等：“通过 MEM 电荷密度研究直接观察 Orbita 1Orderin Manganites”J. Phys. Jpn.. 2190-2193 (1999)

M.Takata 他: "Structure of Endohedral DimetallofullereneSc2@C84" Phys.Rev.Lett.78. 3330-3333 (1997)

M. Takata 等人：“内嵌二金属富勒烯Sc2@C84 的结构”Phys.Rev.Lett.78 (1997)。