Abstract
The high pressure behaviour of cubic silica sodalite has been investigated by ab initio calculations based on density functional theory. The experimentally observed phase transition from the fully-expanded ideal sodalite framework (space group Im3̅m) to a collapsed framework with space group I4̅3m could be successfully reproduced to appear at 0.12 GPa. This transition is discontinuous. The mechanism of the transition can be understood in terms of a tilt of the framework and of deformations of the SiO4-tetrahedra. Discontinuities of the enthalpy, cell volume, Si-O bond lengths and angles at 1.15 and 3.01 Gpa point at further possible pressure-induced iso-symmetric phase transitions in the space group I4̅3m.
© 2001 Oldenbourg Wissenschaftsverlag GmbH
