Effect of pressure on the thermal expansion of MgO up to 8.2 GPa |
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Authors: | J Zhang |
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Institution: | (1) Center for High-Pressure Research (an NSF Science and Technology Center) and Department of Geosciences State University of New York at Stony Brook Stony Brook, NY 11794, USA E-mail: zhang@sbmp04.ess.sunysb.edu Fax: (516)-632-8140 Tel.: (516)-632-6152, US |
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Abstract: | Isobaric volume measurements for MgO were carried out at 2.6, 5.4, and 8.2 GPa in the temperature range 300–1073 K using
a DIA-type, large-volume apparatus in conjunction with synchrotron X-ray powder diffraction. Linear fit of the thermal expansion
data over the experimental pressure range yields the pressure derivative, (∂α/∂P)
T
, of −1.04(8) × 10−6 GPa−1 K−1 and the mean zero-pressure thermal expansion α0,
T
= 4.09(6) × 10−5 K−1. The α0,
T
value is in good agreement with results of Suzuki (1975) and Utsumi et al. (1998) over the same temperature range, whereas
(∂α/∂P)
T
is determined for the first time on MgO by direct measurements. The cross-derivative (∂α2/∂P∂T) cannot be resolved because of large uncertainties associated with the temperature derivative of α at all pressures. The
temperature derivative of the bulk modulus, (∂K
T/∂T)
P
, of −0.025(3) GPa K−1, obtained from the measured (∂α/∂P)
T
value, is in accord with previous findings.
Received: 2 April 1999 / Revised, accepted: 22 June 1999 |
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Keywords: | MgO X-ray diffraction Thermal expansion Equation of state |
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