Ultrasonic lab is operated under Center for High Pressure Research (CHiPR), a National Science Foundation scientific center. We carry out research on the elastic properties of the mantle minerals using ultrasonic interferometric measurements and /or X-ray diffractions. We have developed techniques to perform measurements to 17 GPa and 1500K. These techniques are now been applied to study the major mantle phases, including Olivine, Wadsleyite, Ringwoodite, Pyroxenes, Garnets and Perovskite.
The lab facilities include High Pressure Apparatus and ultrasonic interferometer. The experimental techniques have been developed for both MA-8 type apparatus and DIA-type apparati. Some completed Scientific Projects are listed in Publications. For a broader interest, see also Related References.
Room Temperature Measurements
Polycrystalline specimens of the olivine and beta polymorphs of Mg2SiO4 suitable for acoustic wave velocity measurement were successfully hot-pressed in their stability fields and recovered at room conditions. Compressional (P) and shear (S) wave velocities for these specimens are measured in a 1000-ton Uniaxial Split Cylinder Apparatus (USCA-1000) by in-situ ultrasonic interferometry. We have measured P and S wave velocities to 12.5 GPa for olivine-Mg2SiO4 beta-Mg2SiO4 (Abstract). These new results have tripled the pressure range of previous ultrasonic measurements on olivine and beta-Mg2SiO4 and thus can be used to compare directly to seismic velocities at the transition zone pressures. These data also allow us to test the validity of the finite strain extrapolations of low-pressure data and compare the ultrasonic data with spectroscopic data on single crystals studied in diamond anvil cell.
Measurements at Transition Zone P and T
We have developed techniques to perform ultrasonic interferometry measurements at the same double-stage, 1000-ton Uniaxial Split Cylinder Apparatus (USCA-1000) on millimeter-sized polycrystalline and single-crystal specimens to P ~10 GPa at 1300 oC. In these techniques, 40 MHz LiNbO3 piezoelectric transducers are also used.
Experiments on polycrystalline alumina (Lucalox Al2O3 from General Electric) to 10 GPa at room temperature and 10 GPa 1300 oC have demonstrated that the recovered specimens are re-usable, and the velocity are reversible.
Simultaneous X-ray and Ultrasonic Measurements
We have also successfully performed high pressure acoustic experiments at room temperature and to 600 oC using similar techniques but with in-situ X-ray diffraction for pressure and sample volume determination at NSLS X17B in Brookhaven National Lab.
Sound Velocity of Minerals
Earthquake /Waves
Mantle Minerals
CELL ASSEMBLY
Acoustic Signal of reflections from Cube, Buffer rod and Sample