Open AccessElasticity of MgO to 11 GPa with an independent absolute pressure scale: Implications for pressure calibration
Author(s) -
Li Baosheng,
Woody Kelly,
Kung Jennifer
Publication year - 2006
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2005jb004251
Subject(s) - diffraction , isothermal process , materials science , elasticity (physics) , equation of state , compression (physics) , calibration , shear (geology) , thermodynamics , analytical chemistry (journal) , mineralogy , optics , chemistry , physics , composite material , chromatography , quantum mechanics
P and S wave velocities and unit cell parameters (density) of MgO are measured simultaneously up to 11 GPa using combined ultrasonic interferometry and in situ X‐ray diffraction techniques. The elastic bulk and shear moduli as well as their pressure derivatives are obtained by fitting the measured velocity and density data to the third‐order finite strain equations, yielding K 0S = 163.5(11) GPa, K′ 0S = 4.20(10), G 0 = 129.8(6) GPa, and G′ 0 = 2.42(6), independent of pressure. These properties are subsequently used in a Birch‐Murnaghan equation of state to determine the sample pressures at the observed strains. Comparison of the 300K isothermal compression of MgO indicates that current pressure scales from recent studies are in better than 1.5% agreement. We find that pressures derived from secondary pressure standards (NaCl, ruby fluorescence) at 300K are lower than those from current MgO scales by 5–8% (∼6% on average) in the entire pressure range of the current experiment. If this is taken into account, discrepancy in previous static compression studies on MgO at 300K can be reconciled, and a better agreement with the present study can be achieved.