San Miguel, A;
High-pressure phase transformations, pressure-induced amorphization, and polyamorphic transition of the clathrate Rb6.15 Si46.
Physical Review B - Condensed Matter and Materials Physics
The type-I clathrate Rb6.15 Si46 with partly empty cage sites has been studied up to 36 GPa using Raman spectroscopy, synchrotron x-ray diffraction in diamond-anvil cells, and ab initio total-energy and lattice-dynamics calculations. A first phase transition is observed at 13±1□GPa and a "volume collapse" transition within the clathrate structure is then observed at 24±1□GPa. Pressure-induced amorphization into a high-density amorphous (HDA) state occurs above P=33±1□GPa. The HDA form transforms into a low-density amorphous polymorph during decompression. During the compression study using angle dispersive synchrotron x-ray diffraction techniques we measured bulk modulus parameters for rocksalt-structured TaO, included adventitiously in the clathrate sample [K0 =293 (3) □GPa and K0′ =5.4 (3)]. © 2009 The American Physical Society.
|Title:||High-pressure phase transformations, pressure-induced amorphization, and polyamorphic transition of the clathrate Rb6.15 Si46|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Maths and Physical Sciences
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