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The high-pressure behaviour of the "moganite" polymorph of SiO (sub 2)

Jean-Michel Leger, Julian Haines and Christian Chateau
The high-pressure behaviour of the "moganite" polymorph of SiO (sub 2)
European Journal of Mineralogy (April 2001) 13 (2): 351-359

Abstract

The high-pressure behaviour of the "moganite" polymorph of SiO (sub 2) has been investigated by angle-dispersive, X-ray powder diffraction in a diamond anvil cell at room temperature. The bulk modulus was calculated from the P-V data: B (sub 0) = 32.2(3) GPa with B' (sub 0) fixed to 5.2 as for quartz. The molar volume of moganite becomes lower than the volume of quartz above 5 GPa. Pressure-induced amorphisation occurred progressively; it was complete above 25 GPa. Upon decompression, amorphisation was partially reversible if the maximum pressure reached was below 25-30 GPa and irreversible when the pressure reached was above 45 GPa. The pressure-induced amorphisation of the quartz and moganite polymorphs of silica and phosphorus oxynitride PON, a silica analogue, is related to the distortion of the tetrahedra and, in the case of silica, to the presence of a much denser phase, in which the cation has a higher coordination number.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 13
Serial Issue: 2
Title: The high-pressure behaviour of the "moganite" polymorph of SiO (sub 2)
Affiliation: Centre National de la Recherche Scientifique, Laboratoire de Physico-Chimie des Materiaux, Meudon, France
Pages: 351-359
Published: 200104
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 36
Accession Number: 2001-049317
Categories: General geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute.
Update Code: 200115
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