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Thermoelastic properties of magnesiowustite, (Mg1-xFex)O: determination of the Anderson-Gruneisen parameter by time-of-flight neutron powder diffraction at simultaneous high pressures and temperatures.
Journal of Applied Crystallography
The ability to perform neutron diffraction studies at simultaneous high pressures and high temperatures is a relatively recent development. The suitability of this technique for determining P-V-T equations of state has been investigated by measuring the lattice parameters of Mg1-xFexO ( x = 0.2, 0.3, 0.4), in the range P < 10.3 GPa and 300 < T < 986 K, by time-of-flight neutron powder diffraction. Pressures were determined using metallic Fe as a marker and temperatures were measured by neutron absorption resonance radiography. Within the resolution of the experiment, no evidence was found for any change in the temperature derivative of the isothermal incompressibility, partial derivative K-T/partial derivative T, with composition. By assuming that the equation-of-state parameters either varied linearly or were invariant with composition, the 60 measured state points were fitted simultaneously to a P-V-T-x equation of state, leading to values of partial derivative K-T/partial derivative T = -0.024 (9) GPa K-1 and of the isothermal Anderson-Gruneisen parameter delta(T) = 4.0 (16) at 300 K. Two designs of simultaneous high-P/T cell were employed during this study. It appears that, by virtue of its extended pressure range, a design using toroidal gaskets is more suitable for equation-of-state studies than is the system described by Le Godec, Dove, Francis, Kohn, Marshall, Pawley, Price, Redfern, Rhodes, Ross, Schofield, Schooneveld, Syfosse, Tucker & Welch [Mineral. Mag. (2001), 65, 737-748]. (c) 2008 International Union of Crystallography Printed in Singapore - all rights reserved.
|Title:||Thermoelastic properties of magnesiowustite, (Mg1-xFex)O: determination of the Anderson-Gruneisen parameter by time-of-flight neutron powder diffraction at simultaneous high pressures and temperatures|
|Open access status:||An open access version is available from UCL Discovery|
|Additional information:||Copyright © International Union of Crystallography Author(s) of this paper may load this reprint on their own web site or institutional repository provided that the cover page is retained. Republication of this article or its storage in electronic databases other than as specified above is not permitted without prior permission in writing from the IUCr.|
|Keywords:||X-RAY-DIFFRACTION, POST-PEROVSKITE PHASE, V-T EQUATION, GIGAHERTZ ULTRASONIC INTERFEROMETRY, LOWER MANTLE COMPOSITION, SINGLE-CRYSTAL MGO, PROBABILISTIC TOMOGRAPHY, THERMODYNAMIC EQUATION, THERMAL-PROPERTIES, ELASTIC PROPERTIES|
|UCL classification:||UCL > School of BEAMS
UCL > School of BEAMS > Faculty of Maths and Physical Sciences
UCL > VP Research
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