Skip to Main Content
Skip Nav Destination

High-temperature phase transitions in Steinbach tridymite

Richard F. de Dombal and Michael A. Carpenter
High-temperature phase transitions in Steinbach tridymite
European Journal of Mineralogy (August 1993) 5 (4): 607-622


Tridymite from the Steinbach meteorite has been studied by high- resolution XRD, DSC and hard-mode IR spectroscopy. Phase transitions at 350 and 465 degrees C have been analysed in detail; the 465 degrees C transition is second-order in character and the coefficients in a Landau potential are: G = 1.2(T-738)Q (super 2) + 443Q (super 4) J/mol. This phase change appears to be driven by a volume decrease and the excess free energy is relatively small. The 350 degrees C transition also appears to be continuous and could be close to second-order in character; the excess free energy is again small. Two mechanisms are presented to account for the thermal behaviour; a dynamic model involving the 'flipping' of apical oxygen atoms and a purely displacive model involving shifts in atomic positions and the appearance of an intermediate phase. The first is consistent with the XRD results but does not accord with the IR measurements, while the second satisfies the IR data but not the XRD observations.

ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 5
Serial Issue: 4
Title: High-temperature phase transitions in Steinbach tridymite
Affiliation: University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom
Pages: 607-622
Published: 199308
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 67
Accession Number: 1993-023682
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 1993
Close Modal

or Create an Account

Close Modal
Close Modal