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Elasticity of Single-Crystal MgO to 8 Gigapascals and 1600 Kelvin

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Science  19 Jun 1998:
Vol. 280, Issue 5371, pp. 1913-1916
DOI: 10.1126/science.280.5371.1913

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Abstract

The cross pressure (P) and temperature (T) dependence of the elastic moduli (Cij ) of single-crystal samples of periclase (MgO) from acoustic wave travel times was measured with ultrasonic interferometry: ∂2 C 11/∂PT= (−1.3 ± 0.4) × 10−3 per kelvin; ∂2 C 110/∂PT= (1.7 ± 0.7) × 10−3 per kelvin; and ∂2 C 44/∂PT= (−0.2 ± 0.3) × 10−3 per kelvin. The elastic anisotropy of MgO decreases with increasing pressure at ambient temperature, but then increases as temperature is increased at high pressure. An assumption of zero cross pressure and temperature derivatives for the elastic moduli underestimates the elastic anisotropy and overestimates the acoustic velocities of MgO at the extrapolated high-pressure and high-temperature conditions of Earth's mantle.

  • * Present address: ST541 EPR, Exxon Production Research Company, Post Office Box , Houston, TX 77252–2189, USA.

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