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High temperature studies of sodalites

Fazal, Tabasum (2011)
M.Res. thesis, University of Birmingham.

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Abstract

Aluminosilicate sodalites Na\(_8\)(Al\(_6\)Si\(_6\)O\(_2\)\(_4\))Br\(_2\), Na\(_8\)(Al\(_6\)Si\(_6\)O\(_2\)\(_4\)Cl\(_2\), and Na\(_8\)(Al\(_6\)Si\(_6\)O\(_2\)\(_4\))I\(_2\), were synthesised and subsequently loaded with various amounts of silver by aqueous ion exchange to produce Na\(_8\)-Ag\(_x\)(Al\(_6\)Si\(_6\)O\(_2\)\(_4\))Br\(2\) with x = 0, 2, 4, 6, 8, Naz\(_8\)-Al\(_6\)Si\(_6\)O\(_2\)\(_4\))I\(_2\). Characterisation by X-ray powder diffraction and Rietveld refinements showed that for the chloride and bromide systems the substitution of silver for sodium causes a contraction of the unit cell and M-X bonds in the MX4 tetrahedral units in the sodalite cages, with an expansion of the distance of the metal from the framework oxygen atoms. This can be attributed to the increased covalent bonding in an Ag-X bond vs. a Na-X bond. High temperature X-ray powder diffraction studies were then carried out on these systems and it was found that they all displayed positive thermal expansion from room temperature up to 822ºC. The coefficients of thermal expansion for the bromide system showed a clear trend of decreasing with silver doping, but no clear trends for the chloride system or in the thermal expansion of the M-X or M-O distances in either system were found.

Type of Work:M.Res. thesis.
Supervisor(s):Hriljac, Joseph A.
School/Faculty:Colleges (2008 onwards) > College of Engineering & Physical Sciences
Department:School of Chemistry
Subjects:QD Chemistry
Institution:University of Birmingham
ID Code:1488
This unpublished thesis/dissertation is copyright of the author and/or third parties. The intellectual property rights of the author or third parties in respect of this work are as defined by The Copyright Designs and Patents Act 1988 or as modified by any successor legislation. Any use made of information contained in this thesis/dissertation must be in accordance with that legislation and must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the permission of the copyright holder.
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