Elasticity of MgO to 11 GPa with an independent absolute pressure scale: Implications for pressure calibration

Abstract

[1] 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 0 0S = 4.20(10), G 0 = 129.8(6) GPa, and G 0 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.Citation: Li, B., K. Woody, and J. Kung (2006), Elasticity of MgO to 11 GPa with an independent absolute pressure scale: Implications for pressure calibration,

First Principles Thermodynamics of Minerals at HP–HT Conditions: MgO as a Prototypical Material

“…Lower mantle thermodynamics and rheology are thus largely controlled by periclase and its Fe-bearing analogue (ferropericlase) [16,[107][108][109][110]. (14) and (15) Calculated results of this work are compared to selected experimental data obtained by hydrostatic or quasi-hydrostatic compression in the diamond-anvil cell [90][91][92][93] and ultrasonic measurements [94][95][96][97]. The results of semi-empirical assessments [98,100], other ab initio LDA [59], GGA [61] and empirically-corrected GGA [101] calculations and MD simulations [60,84] are also shown for comparison.…”

“…Figure 7 and Table 4 show the results obtained for the P-V-T equation of state of periclase, as compared to different kinds of experimental data (i.e., static compression in the diamond-anvil cell, ultrasonic measurements, etc.) [89][90][91][92][93][94][95][96][97], semi-empirical modelling of experimental data [98][99][100] and other DFT [59,61,101] and MD [60,84] calculations. The EOS of MgO has been calculated according to Equation (15) in a range of conditions compatible with those realized in the Earth's lower mantle (i.e., P = 0-160 GPa, V/V 0 = 0.65-1.00, T = 0-3000 K).…”

Thermodynamic estimation the compressibility of ferropericlase under high pressure

“…44,45 Meanwhile, FeO has been investigated by Fischer et al 7 and Richet et al 46 In the present study, the experimental results on MgO reported by Li et al 43 and FeO reported by Fischer et al 7 were selected as reference data to calculate the compressibility of (Mg 1−x Fe x )O ferropericlase. In the case of MgO, B 1 = 164(11) GPa, 43 dB 1 /dP = 4.2 43 and V 1 = 11.248 cm 3 /mol. 43 The corresponding values of the elastic parameters for FeO are B 2 = 150 GPa, 7 dB 1 /dP = 3.6 7 and V 2 = 12.256 cm 3 /mol.…”

“…In the case of MgO, B 1 = 164(11) GPa, 43 dB 1 /dP = 4.2 43 and V 1 = 11.248 cm 3 /mol. 43 The corresponding values of the elastic parameters for FeO are B 2 = 150 GPa, 7 dB 1 /dP = 3.6 7 and V 2 = 12.256 cm 3 /mol. 7 The resultant bulk moduli of ferropericlase at the corresponding molar fraction x obtained by substituting the aforementioned elastic data into Eqs.…”

“…Given that MgO is a material of key importance in solid-state physics and Earth sciences, the P-V -T equations of the states of MgO have been extensively studied through experimental investigations 6,10,43 and theoretical calculations. 44,45 Meanwhile, FeO has been investigated by Fischer et al 7 and Richet et al 46 In the present study, the experimental results on MgO reported by Li et al 43 and FeO reported by Fischer et al 7 were selected as reference data to calculate the compressibility of (Mg 1−x Fe x )O ferropericlase. In the case of MgO, B 1 = 164(11) GPa, 43 dB 1 /dP = 4.2 43 and V 1 = 11.248 cm 3 /mol.…”