Pressure-induced homothetic volume collapse in silicon clathrates
Pressure-induced homothetic volume collapse in silicon clathrates
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DOI：
10.1209/epl/i2004-10387-x
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发表时间：
2005-02
期刊：
影响因子：
1.8
通讯作者：
A. Miguel;A. Merlen;P. Toulemonde;T. Kume;S. Floch;A. Aouizerat;S. Pascarelli;G. Aquilanti;O. Mathon;T. Bihan;J. Itié;S. Yamanaka
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文献类型：
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作者：
A. Miguel;A. Merlen;P. Toulemonde;T. Kume;S. Floch;A. Aouizerat;S. Pascarelli;G. Aquilanti;O. Mathon;T. Bihan;J. Itié;S. Yamanaka
结合x射线衍射和x射线吸收光谱研究了掺钡硅包合物Ba8Si46的高压性能。在11.5-14 GPa时，压力诱导的等结构相变与重要的体积崩塌有关。这种转变的特征是含有Ba原子的硅笼的均匀收缩。这种转变发生在5gpa时电子结构的变化之前，这与拉曼光谱观测结果很好地吻合(T. Kume et al., Phys。启。， 90(2003) 155503)，它也具有等构造性质。笼状结构通过相变得以保留，从而获得了原子间距离低至2.13 A的四面体硅。在研究的最高压力为49gpa时，该结构变为不可逆的非晶态。讨论了均匀等构造跃迁的物理成因。
The high-pressure properties of the Ba-doped silicon clathrate Ba8Si46 have been investigated combining X-ray diffraction and X-ray absorption spectroscopy. A pressure-induced isostructural phase transition associated with an important volume collapse takes place at 11.5–14 GPa. This transformation is characterized by the homothetic contraction of the silicon cages containing the Ba atoms. This transition is preceded by a change in the electronic structure at 5 GPa in good agreement with Raman spectroscopy observations (T. Kume et al., Phys. Rev. Lett., 90 (2003) 155503) that it is also of isostructural nature. The cage structure is preserved through the phase transitions allowing to obtain tetrahedral silicon with record interatomic distances as low as 2.13 A. At the highest studied pressure of 49 GPa, the structure becomes irreversibly amorphous. The physical origin of the homothetic isostructural transitions is discussed.