Collapsing cristobalitelike structures in silica analogues at high pressure.
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.
Haines
J
J
Laboratoire de Physico-Chimie de la Matière Condensée, UMR CNRS 5617, Université Montpellier II, cc 003, Place E. Bataillon, 34095 Montpellier Cedex 5, France.
Chateau
C
C
Léger
J M
JM
Bogicevic
C
C
Hull
S
S
Klug
D D
DD
Tse
J S
JS