Acta Crystallographica Section B

Structural Science

Volume 55, Part 5 (October 1999)

research papers

Acta Cryst. (1999). B55, 677-682 [ doi:10.1107/S010876819900347X ]

Crystal structure of moganite-type phosphorus oxynitride: relationship to other twinned-quartz-based structures

J. Haines, C. Chateau, J. M. Léger, A. Le Sauze, N. Diot, R. Marchand and S. Hull

Abstract: The structure of moganite-type phosphorus oxynitride quenched from high-pressure high-temperature conditions has been refined using neutron powder diffraction data. This moganite-type structure, space group I2/a, Z = 12, is slightly less distorted with respect to the Imab aristotype than is moganite (a monoclinic form of silica). A close topological relationship has been identified between the moganite-type and orthorhombic BeH₂ structures indicating that SiO₂, PON and BeH₂ all adopt structures belonging to the twinned-quartz-based group. This group represents another possible structure type for systems composed of corner-sharing AX₄ tetrahedra. Structures of this group are obvious candidates for intermediate phases between the cristobalite and quartz types.

Keywords: Phosphorus oxynitride; Moganite; Twinned-quartz-based structures.