Sound velocities and single-crystal elasticity of orthoenstatite to 1073 K at ambient pressure

Jennifer M. Jackson, Stanislav V. Sinogeikin, Jay D Bass

Research output: Contribution to journalArticle

Abstract

Single-crystal Brillouin spectroscopy measurements have been carried out to 1073 K and ambient pressure to determine the elastic modulus tensor of a natural orthopyroxene, nearly pure Mg end-member (Mg 0.994 Fe 0.002 Al 0.004 ) 2 (Si 0.996 Al 0.004 ) 2 O 6 orthoenstatite. Three single-crystal specimens with orthogonal crystallographic orientations were prepared for Brillouin measurements to determine all the single-crystal elastic moduli (C ij ). The single-crystal elastic moduli were calculated using the measured velocities of sound and our independent measurement of the volume thermal expansion. These are, to our knowledge, the highest temperatures at which the complete single-crystal elastic modulus tensor of orthoenstatite has been measured. The elastic moduli at ambient conditions obtained in this study are in excellent agreement with previous measurements on Mg 2 Si 2 O 6 orthoenstatite (OEN). The elastic anisotropy of OEN is approximately the same at all measured temperatures. The velocities in different directions change at different rates, with C 33 showing the largest temperature dependence (decreasing with temperature almost twice as fast as C 11 or C 22 ). The variation of elastic moduli with temperature is linear up to approximately 673 K, above which some of the moduli decrease with a quadratic dependence on temperature. The non-linear behavior is in accord with recent elastic mode softening observations in orthoenstatite at higher temperatures and could add support to account for a thermally induced solid-state mechanism for the low velocity zone in Earth's upper mantle.

Original languageEnglish (US)
Pages (from-to)1-12
Number of pages12
JournalPhysics of the Earth and Planetary Interiors
Volume161
Issue number1-2
DOIs
StatePublished - Apr 16 2007

Fingerprint

sound velocity
enstatite
elastic modulus
acoustic velocity
elasticity
modulus of elasticity
elastic properties
crystal
single crystals
temperature
tensors
elastic anisotropy
low velocity zone
thermal expansion
softening
orthopyroxene
low speed
upper mantle
Earth mantle
anisotropy

Keywords

  • Brillouin spectroscopy
  • Elasticity
  • Enstatite
  • High-temperature
  • Sound velocities

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Geophysics
  • Physics and Astronomy (miscellaneous)
  • Space and Planetary Science

Cite this

Sound velocities and single-crystal elasticity of orthoenstatite to 1073 K at ambient pressure. / Jackson, Jennifer M.; Sinogeikin, Stanislav V.; Bass, Jay D.

In: Physics of the Earth and Planetary Interiors, Vol. 161, No. 1-2, 16.04.2007, p. 1-12.

Research output: Contribution to journalArticle

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