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Title: Compressional and Shear-Wave Velocities of the Polycrystalline CaGeO3 Perovskite to 10 GPa

Abstract

Compressional and shear-wave velocities and unit-cell volumes of orthorhombic CaGeO{sub 3} perovskite have been measured up to 10GPa at ambient temperature using ultrasonic interferometry in conjunction with synchrotron x radiation. Fitting all velocity and unit-cell volume data to finite-strain equations yields the zero-pressure adiabatic bulk and shear moduli and their pressure derivatives K{sub S0}=194.6 (11)GPa, G{sub 0}=109.5 (5)GPa , KS0'=6.4 (2), G0'=1.7 (1), with an rms misfit of 0.009kms{sup -1} . From the data in the current study, we have observed no discontinuities or elasticity softening for either the bulk or shear moduli up to the peak pressure of 10GPa .

Authors:
;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930496
Report Number(s):
BNL-80431-2008-JA
Journal ID: ISSN 1098-0121; TRN: US0901401
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review B: Condensed Matter and Materials Physics; Journal Volume: 75; Journal Issue: 2
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; AMBIENT TEMPERATURE; ELASTICITY; INTERFEROMETRY; PEROVSKITE; POLYCRYSTALS; PRESSURE RANGE GIGA PA; SHEAR; SYNCHROTRON RADIATION; ULTRASONIC WAVES; VELOCITY; X RADIATION; national synchrotron light source

Citation Formats

Liu,W., and Li, B.. Compressional and Shear-Wave Velocities of the Polycrystalline CaGeO3 Perovskite to 10 GPa. United States: N. p., 2007. Web. doi:10.1103/PhysRevB.75.024107.
Liu,W., & Li, B.. Compressional and Shear-Wave Velocities of the Polycrystalline CaGeO3 Perovskite to 10 GPa. United States. doi:10.1103/PhysRevB.75.024107.
Liu,W., and Li, B.. Mon . "Compressional and Shear-Wave Velocities of the Polycrystalline CaGeO3 Perovskite to 10 GPa". United States. doi:10.1103/PhysRevB.75.024107.
@article{osti_930496,
title = {Compressional and Shear-Wave Velocities of the Polycrystalline CaGeO3 Perovskite to 10 GPa},
author = {Liu,W. and Li, B.},
abstractNote = {Compressional and shear-wave velocities and unit-cell volumes of orthorhombic CaGeO{sub 3} perovskite have been measured up to 10GPa at ambient temperature using ultrasonic interferometry in conjunction with synchrotron x radiation. Fitting all velocity and unit-cell volume data to finite-strain equations yields the zero-pressure adiabatic bulk and shear moduli and their pressure derivatives K{sub S0}=194.6 (11)GPa, G{sub 0}=109.5 (5)GPa , KS0'=6.4 (2), G0'=1.7 (1), with an rms misfit of 0.009kms{sup -1} . From the data in the current study, we have observed no discontinuities or elasticity softening for either the bulk or shear moduli up to the peak pressure of 10GPa .},
doi = {10.1103/PhysRevB.75.024107},
journal = {Physical Review B: Condensed Matter and Materials Physics},
number = 2,
volume = 75,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • Compressional and shear-wave velocities and unit-cell volumes of orthorhombic CaGeO{sub 3} perovskite have been measured up to 10 GPa at ambient temperature using ultrasonic interferometry in conjunction with synchrotron x radiation. Fitting all velocity and unit-cell volume data to finite-strain equations yields the zero-pressure adiabatic bulk and shear moduli and their pressure derivatives K{sub S0}=194.6 (11) GPa, G{sub 0}=109.5 (5) GPa, K{sub S0}{sup '}=6.4 (2), G{sub 0}{sup '}=1.7 (1), with an rms misfit of 0.009 km s{sup -1}. From the data in the current study, we have observed no discontinuities or elasticity softening for either the bulk or shear modulimore » up to the peak pressure of 10 GPa.« less
  • Results are presented for compressional and shear velocities and attenuations in fully brine-saturated tight gas cores with porosities from 3 to 11.9 percent and clay contents from 1 to 38 percent. The influence of porosity, clay content, frequency, and stress on velocities and attenuations were examined using the amplitude spectra of P- and S-waves in the frequency domain. Attenuations of samples were obtained using the spectral ratio method. For a few selected samples the attenuations were also measured using the length correlation method and these results were compared with the spectral ratio results. In tight gas sandstones, the attenuations obtainedmore » were 2 to 5 times greater than the attenuation obtained for Berea sandstone. In general, the presence of clay softens the rock grain contacts causing smaller values of compressional (V{sub P}) and shear (V{sub S}) velocities as the clay content increases. However, the V{sub P}/V{sub S} ratio was found to increase with clay content. Compressional- and shear-wave amplitude spectra exhibited a shift in peak frequency toward lower frequencies for samples with higher clay content when compared to clean samples. Velocities and attenuations were found to be frequency dependent, but the positive slope of both compressional and shear attenuations indicate that scattering starts to dominate at the lower frequency end of the ultrasonic measurements. Both V{sub P} and V{sub S} increased while both compressional and shear attenuations decreased when stress was increased.« less
  • No abstract prepared.
  • Ultrasonic interferometric measurements on polycrystalline Fe{sub 2}SiO{sub 4} spinel were conducted simultaneously with synchrotron X-ray diffraction and X-ray imaging up to 6.5 GPa, 1073 K. The compressional and shear wave velocity data and the volume data were fitted to the third-order finite strain equations to derive the bulk and shear modulus and their pressure and temperature derivatives. The fitting results are as follows: K{sub s0}=204.5(7) GPa,=73.6(3) GPa, K's=4.3(3), G'=1.2(1), ({delta} K{sub s/{delta}} T){sub p}=-0.027(2) GPa/K, and {delta} (G/{delta} T){sub p}=-0.017(1) GPa/K. Comparison of our current results with previous data on (Mg,Fe){sub 2}SiO{sub 4} spinel with different compositions suggests that themore » bulk modulus (Ks) increases slightly with increasing iron content, while the shear modulus (G), in contrast, shows a dramatic decrease. However, the pressure and temperature derivatives of Ks and G remain nearly constant from Mg{sub 2}SiO{sub 4} to Fe{sub 2}SiO{sub 4} spinel with average values of 4.2-4.4, 1.2-1.3,-0.024 GPa/K, and-0.016 GPa/K for K's, G', ({delta} K{sub s/{delta}} T){sub p}, and ({delta} G/{delta} T){sub p}, respectively. The proposed version of equations to describe the effects of iron on the elastic moduli of ringwoodite are: Ks=184.7+18.0 X{sub Fe}, and G=118.7-41.5 X{sub Fe}.« less
  • Compressional and shear velocities measured during cross well seismic surveys are found to decrease during operation of a hot dry rock geothermal system. The relative P and S wave velocity decrease is very close to values predicted by O'Connell and Budiansky (1974), who modeled velocities in rocks containing fluid-saturated and dry cracks. Because our data fit their model quite well, we attribute the velocity decrease to an increased density of the fluid-filled fractures in the reservoir. Fracture density parameters of O'Connell and Budiansky range as high as 0.365 near the main heat transfer areas of the geothermal reservior. The dynamicmore » shear and Young's modulus are significantly lower near the principal reservoir. The dynamic shear and Young's modulus are significantly lower near the principal heat transfer surfaces, but the bulk modulus is largely unaffected. These observations suggest that the velocity differences are caused by fully saturated fractures. We demonstrate that the fractures inferred by this survey may have lengths as large as 70 cm. These fractures may have been caused by shear failure, microcracking associated with thermal drawdown, or thermal stress cracking.« less