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GEOREF RECORD

Aluminate sodalite, Ca (sub 8) [Al (sub 12) O (sub 24) ](CrO (sub 4) ) (sub 2) with tetragonal and orthorhombic superstructures

Ishmael Hassan
Aluminate sodalite, Ca (sub 8) [Al (sub 12) O (sub 24) ](CrO (sub 4) ) (sub 2) with tetragonal and orthorhombic superstructures
European Journal of Mineralogy (June 1996) 8 (3): 477-486

Abstract

TEM has p rovided evidence for ordering of [Ca (sub 4CrO) (sub 4) ] (super 6+) clusters in this aluminate sodalite. at high T (probably > or = 610 K), the [Ca (sub 4CrO) (sub 4) ] (super 6+) clusters in the cubic aluminate sodalite are disordered together with the framework O atoms. As T is lowered (probably between 453 and 610 K), the [Ca (sub 4CrO) (sub 4) ] (super 6+) clusters are ordered and are accompanied by positional modulations of the framework O atoms on the O1 and O2 positions. As T is lowered, different ordering of the clusters produces tetragonal (probably between 432 and 453 K) and orthorhombic phases (probably up to 432 K). Remnants of transitions from an unmodulated cubic structure, to a modulated pseudo-cubic structure, to an orthorhombic superstructure were directly observed in a crystal fragment. The cell parameters for the tetragonal and orthorhombic superstructures, with cubic cell parameter of 9.222 Aa, are (a + b) X (-a + b) X c, and 3a X 2b X c, respectively.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 8
Serial Issue: 3
Title: Aluminate sodalite, Ca (sub 8) [Al (sub 12) O (sub 24) ](CrO (sub 4) ) (sub 2) with tetragonal and orthorhombic superstructures
Author(s): Hassan, Ishmael
Affiliation: University of Kuwait, Department of Geology, Safat, Kuwait
Pages: 477-486
Published: 199606
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 17
Accession Number: 1996-047197
Categories: Mineralogy of silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: 1 table
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199616
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