title: Collapsing cristobalitelike structures in silica analogues at high pressure.
abstract: The cristobalitelike forms of the ternary silica analogues BPO4 and BAsO4 were investigated at high pressure by x-ray diffraction and theoretical methods. The behavior of these compounds represents an extreme case in which the tilt angle of the constituent tetrahedra increases in a spectacular way at high pressure resulting in a major change in topology from a cristobalitelike framework towards a "collapsed cristobalite" structure. These compounds provide the first examples of the collapse of a framework structure to a close-packed form in a continuous manner without an intervening phase transition.
authors.affiliation: Laboratoire de Physico-Chimie de la Matière Condensée, UMR CNRS 5617, Université Montpellier II, cc 003, Place E. Bataillon, 34095 Montpellier Cedex 5, France.
authors.forename: J
authors.initials: J
authors.lastname: Haines
authors.forename: C
authors.initials: C
authors.lastname: Chateau
authors.forename: J M
authors.initials: JM
authors.lastname: Léger
authors.forename: C
authors.initials: C
authors.lastname: Bogicevic
authors.forename: S
authors.initials: S
authors.lastname: Hull
authors.forename: D D
authors.initials: DD
authors.lastname: Klug
authors.forename: J S
authors.initials: JS
authors.lastname: Tse