Baosheng Li ESS Building SUNY Stony Brook Stony Brook, NY 11794 Direct Pressure Measurements and Insights on Current Pressure Scales This research is supported by NSF Elasticity Grand Challenge Grant
Simultaneous P-V-T Eos and Sound Velocity (Vp,Vs) Measurements CCD/SSD Press Incident slits Sample NSLS X17B2 Ultrasonic Interferometer YAG and CCD Camera X-ray Imaging Experimental Techniques
Amp Details of SAM 85 cell assembly Pt NaCl C-heater TC TC Boron sample Cell assembly for ultrasonics at High P and T. Frequency Ultrasonic Interferometry P and S wave travel times (tp, ts) inside the sample are measured at the same time
SEM Image of Hot-pressed MgO Polycrystalline sample Bulk density: 3.57 g/cm3 (99.6% of theoretical density)
Finite Strain Data Analysis 1. Finite Strain Equations rVP2 = (1-2e)5/2(L1+L2e+ ...) (1) rVS2 = (1-2e)5/2(M1+M2e+ ...) (2) with e = [(1-(r/ro)2/3]/2 L1 = KS+(4/3)G; L2 = 5(KS+4G/3) - 3KS(KS’ + 4G’/3) M1 = G; M2 = 5G-3KSG’ 2.Solve for: KS0, Ks0’, G0, G0’,dKS/dT, dG/dT, d2K/dPdT, d2G/dPdT, d2K/dP2, d2G/dP2 by minimizing S(Vmea-Vcal) 2 3. Calculation of sample pressure P = - (1-2e)5/2(C1e+0.5C2e2+ ….) with C1 = 3L1–4M1; C2 = 3L2–4M2+7C1
Comparison of Elastic Properties from Selected Studies 1: This study, 2: Jackson & Niesler (1982); 3: Yoneda (1990); 4: Zha et al. (2000); 5: Sinogeikin and Bass (2000); 6: Chopelas (1992); 7: Karki et al. (1999); 8: Matsui (1999) ; 9: Anderson and Andreatch(1966); 10: Fei (1999); 11: Utsumi et al. (1998); 12: Speziale et al. (2001) ; 13 : Dewaele et al. (2000).
Exp. Points Using NaCl/Ruby P scale Comparison of V/V0 for MgO Collected Using Different P scales 20 GPa 10
Difference Between Calculated Pressures on MgO and Those from NaCl (obs)
RUS Brillouin Scattering P >50 GPa Expanding P T Range for P-V-VP-VS-T- e Measurement
Conclusions • Unit cell volume, P and S wave velocities of MgO have been measured up to ~11GPa and 1073K. • Combined analyses of the volume and velocity data yield direct determination of K, G, K/P, G/P, K/T, G/ T without relying on previous pressure scales (cross-derivatives and second order derivatives can be derived as well). The sample pressure can be directly calculated from the derived • The discrepancies between previous EoS results likely results from pressure range and pressure scales. • Comparison of the 300K isotherm of MgO suggests that MgO EoS from different studies are consistent within <1%. • Direct pressures and those from NaCl/Ruby differ by an average of ~6% at the current experimental pressure range at room T. The difference becomes smaller at temperatures above ~1100k, within the claimed uncertainties of NaCl pressure scales (e.g., Brown, 1993).