Theory and Modeling Division, Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping S-581 83, Sweden.
J Phys Condens Matter. 2010 Nov 3;22(43):435501. doi: 10.1088/0953-8984/22/43/435501. Epub 2010 Oct 7.
The binary CoSn compound has a unique ground state large-void crystal structure, whose stability under pressure has recently been examined. Whereas theoretical results predicted a series of phase transformations, the room temperature experiments did not observe any structural change. We suggest that the large void of a CoSn-type structure could contain natural impurities such as hydrogen, which can influence the thermodynamic stability of a CoSn system and explain the unusual disagreement between the theoretical and experimental results. Based on first-principles calculations we reveal that the contamination of CoSn by hydrogen only results in a subtle change of structural parameters and the equation of state of CoSn, but drastically increases the stability of the CoSn-type phase in comparison with the high-pressure phases predicted earlier. We argue that the hardly detectable natural impurities of light elements in porous compounds like CoSn are able to change the phase equilibria.
二元 CoSn 化合物具有独特的基态大空隙晶体结构，其在压力下的稳定性最近已被检验。虽然理论结果预测了一系列的相变，但室温实验并未观察到任何结构变化。我们认为，CoSn 型结构的大空隙可能包含天然杂质，如氢，这会影响 CoSn 系统的热力学稳定性，并解释理论和实验结果之间的异常分歧。基于第一性原理计算，我们揭示了 CoSn 被氢污染只会导致结构参数和 CoSn 状态方程的细微变化，但与之前预测的高压相相比，CoSn 型相的稳定性大大增加。我们认为，像 CoSn 这样多孔化合物中难以检测到的轻元素的天然杂质能够改变相平衡。
