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Reinvestigation of the zemannite structure and its dehydration behavior; a single-crystal X-ray and atomistic simulation study

Georgia Cametti, Sergey Churakov and Thomas Armbruster
Reinvestigation of the zemannite structure and its dehydration behavior; a single-crystal X-ray and atomistic simulation study
European Journal of Mineralogy (March 2017) 29 (1): 53-61

Abstract

Single-crystal X-ray data were collected in steps of 25 degrees C up to 200 degrees C on a natural sample of zemannite, Mg (sub 0.5) [ZnFe (super 3+) (TeO (sub 3) ) (sub 3) ].4.5H (sub 2) O. Ab initio simulations were performed to determine the hydrogen-bonding network to get better insight into the mechanism of the dehydration process.At room temperature, zemannite is hexagonal with cell parameters a = 9.4301(12) A, c = 7.6692(10) A, V = 590.63(13) A (super 3) The structure was refined in the non-centrosymmetric space group P6 (sub 3) , instead of P6 (sub 3) /m. Ab initio simulations suggested an ordered Fe/Zn distribution at the octahedral sites that resulted in agreement with P6 (sub 3) symmetry.The dehydration starts at 100 degrees C and proceeds with continuous loss of the non-Mg-bonded H (sub 2) O up to 125 degrees C. At 150 degrees C, the interstitial water is lost leading to 3H (sub 2) O pfu. The polyhedral framework does not undergo significant modifications. The unit-cell volume slightly decreases from 590.63(13) A (super 3) at room temperature to 577(2) A (super 3) at 200 degrees C.


ISSN: 0935-1221
EISSN: 1617-4011
Serial Title: European Journal of Mineralogy
Serial Volume: 29
Serial Issue: 1
Title: Reinvestigation of the zemannite structure and its dehydration behavior; a single-crystal X-ray and atomistic simulation study
Affiliation: University of Bern, Institute of Geological Sciences, Bern, Switzerland
Pages: 53-61
Published: 201703
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Germany
References: 17
Accession Number: 2017-025974
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 4 tables
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Schweizerbart'sche Verlagsbuchhandlung. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201716
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