HR: 16:30h
AN: MR34A-03 INVITED     [Abstracts]
TI: Elastic properties of dense oxide minerals and other applications of GHz-ultrasonic interferometry
AU: * Jacobsen, S D
EM: s.jacobsen@gl.ciw.edu
AF: Carnegie Institution of Washington, Geophysical Laboratory, Washington, DC 20015
AU: Reichmann, H J
MR34A-03 AF: Geoforschungszentrum, Telegrafenberg PB4, Potsdam, 14473 Germany
AU: Kantor, A
MR34A-03 AF: Bayerisches Geoinstitut, University of Bayreuth, Bayreuth, 95440 Germany
AU: Spetzler, H
MR34A-03 AF: CIRES, University of Colorado, Boulder, CO 80309
AU: Spetzler, H
MR34A-03 AF: Dept Geological Sci., University of Colorado, Boulder, CO 80309
AU: Smyth, J R
MR34A-03 AF: Dept Geological Sci., University of Colorado, Boulder, CO 80309
AU: Holl, C M
MR34A-03 AF: Dept Geological Sci., University of Colorado, Boulder, CO 80309
AU: Mao, H
MR34A-03 AF: Carnegie Institution of Washington, Geophysical Laboratory, Washington, DC 20015
AU: Hemley, R J
MR34A-03 AF: Carnegie Institution of Washington, Geophysical Laboratory, Washington, DC 20015
AB: An improved high-frequency ultrasonic interferometer has been developed for high-pressure and high-temperature elasticity measurements in the diamond anvil cell. The instrument measures single-crystal compressional and shear-wave travel times, which are converted to sound velocities and elastic moduli for direct application to problems in geophysics and materials. The complete elastic tensor (Cij) of several iron-rich oxide minerals has been measured under hydrostatic compression to ~10 GPa. Pressure-induced mode softening of the C44 elastic constant is observed in magnetite (Fe₃O₄), wustite (Fe_xO) and in iron-rich magnesiowustite (Mg,Fe)O, indicating that strong magnetoelastic coupling is common among these iron-rich oxides well ahead of known structural phase transitions. Purely-polarized elastic strain waves with near-optical wavelengths in minerals at 1-3 GHz have been used to study samples as thin as 20-30 microns with round-trip travel times less than 10 nanoseconds using traditional interferometry. The acoustic properties of thin-film bonds with travel times <3 ns have been studied using interference amplitude ratio techniques, demonstrating that GHz-ultrasonic interferometry may also be applied to study micro-samples and thin films <5 microns thick. GHz-ultrasonic interferometry in shear-wave mode is also being used to monitor liquid-glass phase transitions in common fluid pressure media and as a probe to map the elastic properties of single-crystal chemical vapor deposition (CVD) diamond across the CVD-seed interface.
DE: 3900 MINERAL PHYSICS
SC: Mineral and Rock Physics [MR]
MN: Fall Meeting 2005