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Structure determination of the 2.5 hydrate MgSO (sub 4) phase by simulated annealing

Hongwei Ma, David L. Bish, Hsiu-Wen Wang and Steve J. Chipera
Structure determination of the 2.5 hydrate MgSO (sub 4) phase by simulated annealing
American Mineralogist (July 2009) 94 (7): 1071-1074

Abstract

The crystal structure of the 2.5 hydrate MgSO (sub 4) phase was determined by simulated annealing from laboratory X-ray powder diffraction data measured from 2-140 degrees 2theta using CuKalpha radiation. The 2.5 hydrate is monoclinic, space group C2/c, with unit-cell parameters a=18.8636(4) Aa, b=12.3391(2) Aa, c=8.9957(2) Aa, beta =94.568(2) degrees , V=2087.1(6) Aa (super 3) , and Z=16. The model was refined using fundamental-parameters Rietveld refinement, converging to R (sub wp) =8.89%, R (sub p) =6.61%, R (sub exp) =3.33%, R (sub Bragg) =3.95%, and chi (super 2) =2.67. The refined structure is consistent with a formula of 2.5 H (sub 2) O. Bond-valence calculations for the refined model show that the structure is chemically sensible. In the refined structure, [Mg(O,H (sub 2) O) (sub 6) ] octahedra and [SO (sub 4) ] tetrahedra build up 2-D double-sheet slabs by sharing vertex O atoms, which are held together by inter-slab H-bonds involving (SO (sub 4) ) (super 2-) groups and H (sub 2) O molecules coordinated with Mg (super 2+) cations to form the layer structure of the 2.5 hydrate phase.


ISSN: 0003-004X
EISSN: 1945-3027
Coden: AMMIAY
Serial Title: American Mineralogist
Serial Volume: 94
Serial Issue: 7
Title: Structure determination of the 2.5 hydrate MgSO (sub 4) phase by simulated annealing
Affiliation: Indiana University, Department of Geological Sciences, Bloomington, IN, United States
Pages: 1071-1074
Published: 200907
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 28
Accession Number: 2009-084986
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 1 table
Secondary Affiliation: Chesapeake Energy Corporation, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Abstract, copyright, Mineralogical Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 200946
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