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Title: Structures of Three Dehydration Products of Bischofite from in situ Synchrotron Powder Diffraction Data(MgCL2*nH2O;n=1,2,4)

Abstract

High-quality in situ synchrotron powder diffraction data have been used to investigate the decomposition products of bischofite in the temperature range 298 {<=} T {<=} 873 K. At least eight phases could be identified: MgCl{sub 2}{center_dot}nH{sub 2}O (n = 1, 2, 4 and 6), MgOHCl{center_dot}nH{sub 2}O (0 {<=} n {<=} 1.0), MgCl{sub 2} and MgO. The crystal structures of three magnesium chloride hydrates MgCl{sub 2}{center_dot}nH{sub 2}O (n = 1, 2, 4) were determined ab initio, replacing published Rietveld refinements from low-quality powder diffraction data based on similarity criteria. MgCl{sub 2}{center_dot}4H{sub 2}O was found to be disordered and has been correctly determined for the first time. The crystal structures of bishcofite and MgCl{sub 2}4H{sub 2}O consist of discrete Mg(H{sub 2}O){sub 6} and MgCl{sub 2}(H{sub 2}O){sub 4} octahedra, respectively. The crystal structure of MgCl{sub 2}{center_dot}2H{sub 2}O is formed by single chains of edge-sharing MgCl{sub 2}(H{sub 2}O){sub 4} octahedra, while in the case of MgCl{sub 2}H{sub 2}O double chains of edge-sharing MgCl(H{sub 2}O){sub 5} octahedra are found. The phases in the system MgCl{sub 2}-H{sub 2}O are intermediates in the technologically important process of MgO and subsequently Mg production. The same phases were recently found to be of key importance in the understanding ofmore » cracks in certain magnesia concrete floors.« less

Authors:
; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930341
Report Number(s):
BNL-81054-2008-JA
Journal ID: ISSN 0108-7681; ASBSDK; TRN: US0901368
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Acta Crystallographica Section B: Structural Science; Journal Volume: 63
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 43 PARTICLE ACCELERATORS; CONCRETES; CRYSTAL STRUCTURE; DEHYDRATION; DIFFRACTION; FLOORS; HYDRATES; MAGNESIUM CHLORIDES; MINERALS; POWDERS; SYNCHROTRON RADIATION; national synchrotron light source

Citation Formats

Sugimoto,K., Dinnebeir, R., and Hanson, J.. Structures of Three Dehydration Products of Bischofite from in situ Synchrotron Powder Diffraction Data(MgCL2*nH2O;n=1,2,4). United States: N. p., 2007. Web. doi:10.1107/S0108768107002558.
Sugimoto,K., Dinnebeir, R., & Hanson, J.. Structures of Three Dehydration Products of Bischofite from in situ Synchrotron Powder Diffraction Data(MgCL2*nH2O;n=1,2,4). United States. doi:10.1107/S0108768107002558.
Sugimoto,K., Dinnebeir, R., and Hanson, J.. Mon . "Structures of Three Dehydration Products of Bischofite from in situ Synchrotron Powder Diffraction Data(MgCL2*nH2O;n=1,2,4)". United States. doi:10.1107/S0108768107002558.
@article{osti_930341,
title = {Structures of Three Dehydration Products of Bischofite from in situ Synchrotron Powder Diffraction Data(MgCL2*nH2O;n=1,2,4)},
author = {Sugimoto,K. and Dinnebeir, R. and Hanson, J.},
abstractNote = {High-quality in situ synchrotron powder diffraction data have been used to investigate the decomposition products of bischofite in the temperature range 298 {<=} T {<=} 873 K. At least eight phases could be identified: MgCl{sub 2}{center_dot}nH{sub 2}O (n = 1, 2, 4 and 6), MgOHCl{center_dot}nH{sub 2}O (0 {<=} n {<=} 1.0), MgCl{sub 2} and MgO. The crystal structures of three magnesium chloride hydrates MgCl{sub 2}{center_dot}nH{sub 2}O (n = 1, 2, 4) were determined ab initio, replacing published Rietveld refinements from low-quality powder diffraction data based on similarity criteria. MgCl{sub 2}{center_dot}4H{sub 2}O was found to be disordered and has been correctly determined for the first time. The crystal structures of bishcofite and MgCl{sub 2}4H{sub 2}O consist of discrete Mg(H{sub 2}O){sub 6} and MgCl{sub 2}(H{sub 2}O){sub 4} octahedra, respectively. The crystal structure of MgCl{sub 2}{center_dot}2H{sub 2}O is formed by single chains of edge-sharing MgCl{sub 2}(H{sub 2}O){sub 4} octahedra, while in the case of MgCl{sub 2}H{sub 2}O double chains of edge-sharing MgCl(H{sub 2}O){sub 5} octahedra are found. The phases in the system MgCl{sub 2}-H{sub 2}O are intermediates in the technologically important process of MgO and subsequently Mg production. The same phases were recently found to be of key importance in the understanding of cracks in certain magnesia concrete floors.},
doi = {10.1107/S0108768107002558},
journal = {Acta Crystallographica Section B: Structural Science},
number = ,
volume = 63,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}