Yamanaka Takamitsu
Department of Earth and Space Science, Graduate School of Science, Osaka University, Machikaneyama, Toyonaka, Osaka 560-0043, Japan.
J Synchrotron Radiat. 2005 Sep;12(Pt 5):566-76. doi: 10.1107/S0909049505022016. Epub 2005 Aug 16.
The bright source and highly collimated beam of synchrotron radiation offers many advantages for single-crystal structure analysis under non-ambient conditions. The structure changes induced by the lattice-electron interaction under high pressure have been investigated using a diamond anvil pressure cell. The pressure dependence of electron density distributions around atoms is elucidated by a single-crystal diffraction study using deformation electron density analysis and the maximum entropy method. In order to understand the bonding electrons under pressure, diffraction intensity measurements of FeTiO3 ilmenite and gamma-SiO2 stishovite single crystals at high pressures were made using synchrotron radiation. Both diffraction studies describe the electron density distribution including bonding electrons and provide the effective charge of the cations. In both cases the valence electrons are more localized around the cations with increasing pressure. This is consistent with molecular orbital calculations, proving that the bonding electron density becomes smaller with pressure. The thermal displacement parameters of both samples are reduced with increasing pressure.
同步辐射的明亮光源和高度准直的光束为非环境条件下的单晶结构分析提供了许多优势。利用金刚石对顶砧压力室研究了高压下晶格 - 电子相互作用引起的结构变化。通过使用变形电子密度分析和最大熵方法的单晶衍射研究，阐明了原子周围电子密度分布的压力依赖性。为了理解高压下的成键电子，利用同步辐射对钛酸亚铁钛铁矿和γ - 二氧化硅斯石英单晶在高压下进行了衍射强度测量。这两项衍射研究都描述了包括成键电子在内的电子密度分布，并提供了阳离子的有效电荷。在这两种情况下，随着压力增加，价电子在阳离子周围的局域性更强。这与分子轨道计算结果一致，证明成键电子密度随压力减小。两个样品的热位移参数都随着压力增加而减小。
