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.
Klug, D., Rousseau, R., Uehara, K., Bernasconi, M., Le Page, Y., Tse, J. (2001). Ab initio molecular dynamics study of the pressure-induced phase transformations in cristobalite. PHYSICAL REVIEW. B, CONDENSED MATTER, 63(10), 1041061-1041065 [10.1103/PhysRevB.63.104106].
Ab initio molecular dynamics study of the pressure-induced phase transformations in cristobalite
BERNASCONI, MARCO;
2001
Abstract
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.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.