Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by Méducin, F. Articles by Marshall, W. G. Search for Related Content GeoRef GeoRef Citation

Study of cation order-disorder in MgAl₂O₄ spinel by in situ neutron diffraction up to 1600 K and 3.2 GPa

¹ Centre de Recherche sur la Matière Divisée (CRMD) Unité Mixte de Recherche 6619 du CNRS et de l’Université d’Orléans, 1bis, rue de la, Férollerie, 45071 Orléans Cedex 2, France
² Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EQ, U.K.
³ Laboratoire de Physique des Milieux Condensés, Université Pierre et Marie Curie, 75252 Paris, France
⁴ ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX, U.K.

Correspondence: ^* E-mail: meducin{at}cnrs-orleans.fr

The temperature-dependence of the cation distribution in synthetic spinel (MgAl₂O₄) was investigated using in situ time-of-flight neutron powder diffraction at ISIS, the pulsed-neutron source at the Rutherford Appleton Laboratory. Neutron diffraction patterns of stoichiometric MgAl₂O₄ were collected on heating from room temperature to 1600 K at pressures of 2.6 GPa. The cation distribution was determined directly from site occupancies obtained by Rietveld refinement. The equilibrium non-convergent ordering was analyzed using the O’Neill-Navrotsky (1983) thermodynamic model, which fits the observed behavior well over the temperature range of the measurements. Fitting the data between 790 and 1600 K yields = 31(6) kJ/mol and ß = –20(13) kJ/mol in the expression for the free energy of ordering. The high-pressure temperature-dependent behavior, as compared to equivalent ambient-pressure behavior, demonstrates that disordering occurs to a much greater extent in MgAl₂O₄ at high pressure and that pressure favors disordering toward the inverse structure.

This article has been cited by other articles:

				F. Nestola, T. B. Ballaran, T. Balic-Zunic, F. Princivalle, L. Secco, and A. Dal Negro Comparative compressibility and structural behavior of spinel MgAl2O4 at high pressures: The independency on the degree of cation order American Mineralogist, November 1, 2007; 92(11-12): 1838 - 1843. [Abstract] [Full Text] [PDF]

				M. A. Carpenter Elastic properties of minerals and the influence of phase transitions American Mineralogist, February 1, 2006; 91(2-3): 229 - 246. [Abstract] [Full Text] [PDF]

				S. A. T. Redfern Neutron Powder Diffraction Studies of Order-Disorder Phase Transitions and Kinetics Reviews in Mineralogy and Geochemistry, January 1, 2006; 63(1): 145 - 170. [Full Text] [PDF]

				J. B. Parise High Pressure Studies Reviews in Mineralogy and Geochemistry, January 1, 2006; 63(1): 205 - 231. [Full Text] [PDF]

				S. M. Antao, I. Hassan, W. A. Crichton, and J. B. Parise Effects of high pressure and high temperature on cation ordering in magnesioferrite, MgFe2O4, using in situ synchrotron X-ray powder diffraction up to 1430 K and 6 GPa American Mineralogist, October 1, 2005; 90(10): 1500 - 1505. [Abstract] [Full Text] [PDF]

				H. St.C. O'NEILL, M. JAMES, W. A. DOLLASE, and S. A. T. REDFERN Temperature dependence of the cation distribution in CuAl2O4 spinel European Journal of Mineralogy, August 1, 2005; 17(4): 581 - 586. [Abstract] [Full Text] [PDF]

				A. I. Turkin and V. A. Drebushchak Cation distribution in MgFe2O4 vs. pressure and temperature: Experiments in a "piston-cylinder" apparatus American Mineralogist, April 1, 2005; 90(4): 764 - 767. [Abstract] [Full Text] [PDF]