权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Observation and Simulation of atomic motion in the Eath internal materials

地球内部材料中原子运动的观测与模拟

基本信息

批准号：
09640570
负责人：
YOSHIASA Akira
金额：
$ 2.24万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09640570/
关键词：
the Eath internal materials diffraction method EXAFS spectroscopy thermal motion ionic conduction effective pair potential phase transition molecular dynamic simulation 回析法有効二体間ポランシャル非調和熱振動解析下部マントルの導電機構ペロブスカイト型固溶体 EXAFS 固体イ

项目摘要

The usefulness of Extended X-ray absorption fine structure (EXAFS) spectroscopy arid diffraction method in studying vibration dynamics has been discussed by this study. Our studies have explored the possibility that EXAFS and diffraction experiments provide an effective interatomic potential and an effective adiabatic one-particle potential with temperaturew-independent shape, respectively, from each Debye-Waller factor. EXAFS method has been utilized as a reliability test for the interatomic potentials in molecular dynamics simulation. Reliable representation of interatomic potential is important for better understanding the thermal properties of the Earth intrenal materials.Precise crystal structure and thermal properties in many materials in the Earth's mantle such as majorite garnet, magnesia wustite, MgSiO3 perovskite, Mg2SiO4 spinel and stishovite heve been revealed by the EXAFS and diffraction method. In the potential parameter fitting, we have directly carried out the numerical integration of the EXAFS function and evaluated the anharmonic effective pair potential. The phonon energies have been estimated using the potential parameter by calculating the dynamical matrix. The Gruneisen parameter is also calculated from the obtained parameter values. The vibrational motion of pair of atoms depend on the lattice type and chemical bonding. Vibrational properties in materials is influenced not only by pressure but also by coordination number The effective pair potential is affected largely by the change in coordination number at a phase transition point.. High pressure phase with higher coordination number has broader effective pair potential than low pressure phase with lower coordination number. Ionic conduction mechanism in menerals has been discussed based on the effective pair potential and distribution of cation-anion distances. The strongly correlated displacement can be attributed to covalent bonds which interact locally.

本研究讨论了扩展 X 射线吸收精细结构 (EXAFS) 光谱和衍射方法在研究振动动力学中的有用性。我们的研究探索了 EXAFS 和衍射实验分别根据每个德拜-沃勒因子提供具有与温度无关的形状的有效原子间势和有效绝热单粒子势的可能性。 EXAFS方法已被用作分子动力学模拟中原子间势的可靠性测试。原子间势的可靠表示对于更好地了解地球内部材料的热性质具有重要意义。通过EXAFS和衍射方法揭示了地幔中许多材料的精确晶体结构和热性质，例如重石榴石、镁方铁矿、MgSiO3钙钛矿、Mg2SiO4尖晶石和石英石。在势参数拟合中，我们直接对EXAFS函数进行数值积分，评估非简谐有效电对势。通过计算动力学矩阵，使用势参数估计了声子能量。 Gruneisen 参数也是根据获得的参数值计算的。原子对的振动运动取决于晶格类型和化学键。材料的振动特性不仅受压力的影响，还受配位数的影响。有效对位势很大程度上受相变点配位数变化的影响。配位数较高的高压相比配位数较低的低压相具有更宽的有效对位势。基于有效对电势和阴阳离子距离分布，讨论了矿物中的离子传导机制。强相关的位移可归因于局部相互作用的共价键。