Structure and Hydrogen Bonding in CaSiD 1+ x : Issues About Covalent Bonding
Structure and Hydrogen Bonding in CaSiD 1+ x : Issues About Covalent Bonding
复制标题
CaSiD 1 x 中的结构和氢键：关于共价键的问题
DOI：
10.1103/physrevb.74.224101
复制
发表时间：
2006
影响因子：
3.7
通讯作者：
T. Yildirim
中科院分区：
文献类型：
--
作者：
Hui Wu;Wei Zhou;T. Udovic;J. Rush;T. Yildirim
本文报道了我们的高分辨中子粉末衍射和中子振动能谱研究，结合第一性原理计算，揭示了这种新型氢化物中的氚结构和成键。结构和光谱结果都表明，对于$xg0$，D原子开始占据{\mathm{Ca}}{3}\mathm{Si}$间隙位置。相应的键长$1.82\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$，{Si}\Text{\EnsureMath{-}}\Mathm{D}$被确定为完全大于理论预测的$0.24\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$。因此，我们的中子测量结果与这些计算所表明的强共价态的{Mathrm{Si}\Text{\susureath{-}}\mathm{H}$成键是不一致的，这一结果可能会对一些正在进行的由Si合金化破坏稳定的金属-氢系统的研究产生影响。
We report here our high-resolution neutron powder diffraction and neutron vibrational spectroscopy study of ${\mathrm{CaSiD}}_{1+x}$ along with first-principles calculations, which reveal the deuterium structural arrangements and bonding in this novel alloy hydride. Both the structural and spectroscopic results show that, for $xg0$, D atoms start occupying a ${\mathrm{Ca}}_{3}\mathrm{Si}$ interstitial site. The corresponding $\mathrm{Si}\text{\ensuremath{-}}\mathrm{D}$ bond length is determined to be $1.82\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$, fully $0.24\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$ larger than predicted by theory. Thus, our neutron measurements are at odds with the strongly covalent $\mathrm{Si}\text{\ensuremath{-}}\mathrm{H}$ bonding in ${\mathrm{CaSiH}}_{1+x}$ that such calculations suggest, a result which may have implications for a number of ongoing studies of metal-hydrogen systems destabilized by Si alloying.