The mechanism for the pressure-induced transformation of cristobalite to stishovite and post-stishovite phases has been obtained from constant pressure ab initio molecular dynamics simulations. The cristobalite to stishovite transformation is found to be a two step process where SiO4 tetrahedra first rotate followed by a lattice distortion to yield the six-coordinated stishovite structure. Further compression of stishovite yields the CaCl2 structure and is followed by another six-coordinated structure with symmetry P21/n (at 11 Mbars) which remains stable to a pressure of about 14 Mbars and then transforms into a nine-coordinated P21/m structure.
|Number of pages||5|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Jan 1 2001|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics