Yildirim Can, Micoulaut Matthieu, Boolchand Punit, Kantor Innokenty, Mathon Olivier, Gaspard Jean-Pierre, Irifune Tetsuo, Raty Jean-Yves
SPIN-Université de Liège, Institut de Physique B5, 4000 Sart-Tilman, Belgium.
Laboratoire de Physique Théorique de la Matière Condensée, Paris Sorbonne Universités, UPMC, 4, place Jussieu 75252 Paris Cedex 05, France.
Sci Rep. 2016 Jun 7;6:27317. doi: 10.1038/srep27317.
Pressure induced structural modifications in vitreous GexSe100-x (where 10 ≤ x ≤ 25) are investigated using X-ray absorption spectroscopy (XAS) along with supplementary X-ray diffraction (XRD) experiments and ab initio molecular dynamics (AIMD) simulations. Universal changes in distances and angle distributions are observed when scaled to reduced densities. All compositions are observed to remain amorphous under pressure values up to 42 GPa. The Ge-Se interatomic distances extracted from XAS data show a two-step response to the applied pressure; a gradual decrease followed by an increase at around 15-20 GPa, depending on the composition. This increase is attributed to the metallization event that can be traced with the red shift in Ge K edge energy which is also identified by the principal peak position of the structure factor. The densification mechanisms are studied in details by means of AIMD simulations and compared to the experimental results. The evolution of bond angle distributions, interatomic distances and coordination numbers are examined and lead to similar pressure-induced structural changes for any composition.
利用X射线吸收光谱（XAS）以及补充的X射线衍射（XRD）实验和从头算分子动力学（AIMD）模拟，研究了压力诱导的玻璃态GexSe100-x（其中10 ≤ x ≤ 25）的结构变化。当按降低的密度进行标度时，观察到距离和角度分布的普遍变化。在高达42 GPa的压力值下，所有成分均保持非晶态。从XAS数据中提取的Ge-Se原子间距离显示出对施加压力的两步响应；先是逐渐减小，然后在15 - 20 GPa左右增加，这取决于成分。这种增加归因于金属化事件，该事件可通过Ge K边能量的红移来追踪，这也由结构因子的主峰位置确定。通过AIMD模拟详细研究了致密化机制，并与实验结果进行了比较。研究了键角分布、原子间距离和配位数的演变，结果表明任何成分都会导致类似的压力诱导结构变化。
