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The coupling between magnetic and cation ordering; a macroscopic approach

Richard J. Harrison and Andrew Putnis
The coupling between magnetic and cation ordering; a macroscopic approach
European Journal of Mineralogy (December 1997) 9 (6): 1115-1130

Abstract

A macroscopic model of magnetic and cation ordering is derived and applied to magnetite, magnesioferrite and the magnetite-spinel solid solution (Fe (sub 3) O (sub 4) ) (sub x) (MgAl (sub 2) O (sub 4) ) (sub 1-) (sub x) . For pure Fe (sub 3) O (sub 4) and MgFe (sub 2) O (sub 4) , the change in free energy due to the process of non-convergent cation ordering, relative to the disordered state, is given by a Landau potential equation. The coupling constant for MgFe (sub 2) O (sub 4) is determined as lambda = 9690 J/mole. In cases where the rates of cation are magnetic ordering are similar, coupling leads to enhanced degrees of order at low T, significantly affecting the magnitude and shape of the specific heat capacity anomaly associated with magnetic ordering, and the C (sub p) anomaly in Fe (sub 3) O (sub 4) is shown to be reproduced when coupling to the non-convergent cation ordering process is taken into account. Possible implications in the magnetite-spinel series are discussed.


ISSN: 0935-1221
Serial Title: European Journal of Mineralogy
Serial Volume: 9
Serial Issue: 6
Title: The coupling between magnetic and cation ordering; a macroscopic approach
Affiliation: University of Cambridge, Department of Earth Sciences, Cambridge, United Kingdom
Pages: 1115-1130
Published: 199712
Text Language: English
Publisher: Schweizerbart'sche Verlagsbuchhandlung (Naegele u. Obermiller), Stuttgart, Federal Republic of Germany
References: 41
Accession Number: 1999-013164
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Secondary Affiliation: Universitaet Muenster, DEU, Federal Republic of Germany
Country of Publication: Germany
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United KingdomTwickenhamUKUnited Kingdom
Update Code: 199905
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