Dynamics and equation of state of hydrogen clathrate hydrate as a function of cage occupation
Dynamics and equation of state of hydrogen clathrate hydrate as a function of cage occupation
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DOI：
10.1016/j.commatsci.2005.03.022
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发表时间：
2006-05
影响因子：
3.3
通讯作者：
T. Inerbaev;V. Belosludov;R. Belosludov;M. Sluiter;Y. Kawazoe
中科院分区：
文献类型：
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作者：
T. Inerbaev;V. Belosludov;R. Belosludov;M. Sluiter;Y. Kawazoe
最近发现的氢笼形水合物具有在适度压力下有效储存分子氢的潜力，引起了重大的科学兴趣。对于可以储存的氢的量至关重要的是占据水合物笼形物主体结构中的笼的氢分子的数量。笼舍占有率的实验数据存在争议，最初实验的可重复性受到质疑。因此，在本报告中，我们研究的动态和热力学性质的氢笼形水合物作为笼占用的功能，使用晶格动力学计算，以确定在不同的外部条件下最有利的占用。晶格动力学研究表明，所有的氢水合物与多物种每个笼是动态稳定的，声子谱强烈依赖于笼占有率。因此，所有的热力学函数随笼占有率显著变化。结果表明，量子零点振动是热力学性质的根本重要性。状态方程已被估计为温度和笼占有率的函数。
The recent discovery of hydrogen clathrate hydrate with potential for efficient storage of molecular hydrogen at modest pressure has initiated significant scientific interest. Of critical importance for the amount of hydrogen that can be stored is the number of hydrogen molecules that occupy the cages in the hydrate clathrate host structure. The experimental data of cage occupancy is controversial, and the reproducibility of the initial experiment has been questioned. Therefore, in the present report we study the dynamic and thermodynamic properties of hydrogen clathrate hydrate as a function of cage occupancy using lattice dynamics calculations in order to determine the most favored occupancy at different external conditions. Lattice dynamics investigations show that all hydrogen hydrates with multiple species per cage are dynamically stable and phonon spectra strongly depend on the cage occupancy. As a result all thermodynamic functions vary significantly with cage occupancy. It is shown that quantum zero-point vibrations are of fundamental importance for the thermodynamic properties. The equation of state has been estimated as a function of temperature and cage occupancy.