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Phase transitions and microstructures in natural kaliophilite

Daniela Cellai, Michael A. Carpenter and Peter J. Heaney
Phase transitions and microstructures in natural kaliophilite
European Journal of Mineralogy (December 1992) 4 (6): 1209-1220


Measurements of unit cell dimensions from room T to 895 degrees C indicate the existence in kaliophilite of a displacive transition at approx 725 degrees C between two hexagonal phases with the same unit cell. A symmetry change of P6 (sub 3) 22 right and left arrows P6 (sub 3) is tentatively suggested, with the concomitant development of merohedral twins. Spontaneous strain determinations suggest that the transition is close to being tricritical in character. Above approx 750 degrees C kaliophilite crystals undergo a first order epitaxial phase transition to a different hexagonal phase with a 8.9, c 8.4 Angstrom . The presence of twins and heterogeneously distributed linear defects seen by TEM are interpreted respectively as transformation twins and stacking defects incorporated during crystal growth. The thermal evolution of kaliophilite is sufficiently different from that of kalsilite to indicate that it has a different framework topology and is not a true stuffed tridymite structure.

ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 4
Serial Issue: 6
Title: Phase transitions and microstructures in natural kaliophilite
Affiliation: University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom
Pages: 1209-1220
Published: 199212
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 24
Accession Number: 1995-056240
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables
N40°49'00" - N40°49'00", E14°25'60" - E14°25'60"
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199520
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