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The thermoelastic properties Of MgSO4 center dot 7D(2)O (epsomite) from powder neutron diffraction and ab initio calculation

Fortes, Andrew D., Wood, Ian Geoffrey, Alfredsson, Maria, Vocadlo, Lidunka, Knight, Kevin S. (2006) The thermoelastic properties Of MgSO4 center dot 7D(2)O (epsomite) from powder neutron diffraction and ab initio calculation. European Journal of Mineralogy, 18 (4). pp. 449-462. ISSN 0935-1221. (doi:10.1127/0935-1221/2006/0018-0449) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided. (Contact us about this Publication)
Official URL
http://dx.doi.org/10.1127/0935-1221/2006/0018-0449

Abstract

time-of-flight powder neutron diffraction has been used to measure the molar volume of MgSO4.7D(2)O (i) from 1.8 - 300 K at ambient pressure, (ii) from 50 - 290 K at 1.4, 3.0, and 4.5 kbar, (iii) from 0 - 5.5 kbar at 290 K, and (iv) from 0 - 4.5 kbar at 50 K. The data have allowed us to determine the temperature dependence of the incompressibility, (partial derivative K/partial derivative T)(p), (thermodynamically equivalent to the pressure dependence of the thermal expansion, (partial derivative alpha/partial derivative P)(T)) of epsomite throughout its stability field. We observed that the a-axis exhibits negative thermal expansion, alpha(a), from 30 - 250 K at room pressure, turning positive above 250 K and being zero below 30 K. However, each of the crystallographic axes exhibits a sharp change in (partial derivative alpha/partial derivative T) at similar to 125 K, and this appears to correspond to significant changes in the axial incompressibilities with the a- and c-axes softening, and the b-axis stiffening considerably below similar to 125 K. Our thermoelastic results are in agreement with ab initio calculations at zero Kelvin; however the calculations offer no obvious insight into the mechanism responsible for the change in behaviour at low temperature.

Item Type: Article
DOI/Identification number: 10.1127/0935-1221/2006/0018-0449
Additional information: ISI Document Delivery No.: 068TZ Times Cited: 3 Cited Reference Count: 63 Fortes, Andrew D. Wood, Ian G. Alfredsson, Maria Vocadlo, Lidunka Knight, Kevin S.
Uncontrolled keywords: epsomite neutron diffraction high-pressure incompressibility thermal expansion
Subjects: Q Science
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Maria Alfredsson
Date Deposited: 01 Sep 2008 14:09 UTC
Last Modified: 28 May 2019 13:40 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/4777 (The current URI for this page, for reference purposes)
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