Physics of the Earth and Planetary Interiors 143–144 (2004) 559–574 Modern techniques in measuring elasticity of Earth materials at high pressure and high temperature using ultrasonic interferometry in conjunction with synchrotron X-radiation in multi-anvil apparatus Baosheng Li a,∗ , Jennifer Kung a , Robert C. Liebermann a,b a Mineral Physics Institute, Stony Brook University, Stony Brook, NY 11794-2100, USA b Department of Geosciences, Stony Brook University, Stony Brook, NY 11794-2100, USA Received 13 February 2003; received in revised form 4 July 2003; accepted 25 September 2003 Abstract In the past 6 years, state-of-the-art techniques have been developed for the studies of elastic properties of polycrystalline and single-crystal materials using simultaneous ultrasonic and X-ray diffraction techniques at high pressures and tempera- tures in multi-anvil apparatus. The capability of these techniques is illustrated using recent data for mantle phases such as forsterite, wadsleyite, CaSiO 3 perovskite, and (MgFe)O ferripericlase. Adaptation of the X-radiography technique enables direct measurements of sample length at high pressures and temperatures, enabling studies of unquenchable phases, liquids, and multi-phase aggregates. The use of dual-mode transducers produces P and S wave data at the same pressure and temper- ature conditions in a single acoustic experiment, thereby eliminating the uncertainties caused by the need for interpolating travel-time data to calculate the elastic wave velocities, and bulk and shear moduli at high pressure and temperature. Imple- mentation of the transfer function method for travel-time measurements opens new opportunities for studying time-dependent processes using ultrasonic measurements, such as phase transformations and plastic deformation. © 2004 Elsevier B.V. All rights reserved. Keywords: Elasticity; Ultrasonic interferometry; Equation-of-state; X-radiography; Multi-anvil apparatus 1. Introduction Elastic properties of Earth materials at high pres- sure and high temperature are crucial for understand- ing the composition, structure and dynamics of the Earth. Seismological investigations provide the pri- mary source of information about the properties and processes of the Earth’s interior in the form of density ∗ Corresponding author. Tel.: +1-631-632-9642; fax: +1-631-632-8410. E-mail address: baosheng.li@sunysb.edu (B. Li). and velocity profiles as a function of depth. Seismic tomography on a global scale reveals lateral variations of compressional (P) and shear (S) wave velocities and densities at various depths of the Earth’s interior, reflecting differences of chemical composition, min- eralogy, and/or temperature. Successful interpretation of these seismic models in terms of these variables requires experimental and theoretical information on the elasticity of deep Earth materials under elevated conditions of pressure and temperature. Ultrasonic techniques (e.g., McSkimin, 1950) have been used extensively in the last four decades to 0031-9201/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.pepi.2003.09.020