Chapter 3 - Simultaneous equation of state, pressure calibration and sound velocity measurements to lower mantle pressures using multi-anvil apparatus

Abstract

This chapter presents a state-of-art technique for the study of elastic properties of polycrystalline and single crystal materials using simultaneous ultrasonic and X-radiation techniques at high pressures and temperatures in Kawai type multi-anvil high pressure apparatus. Multiple techniques for measuring acoustic travel times using ultrasonic interferometry, sample unit-cell volume using X-ray diffraction, and specimen length using X-radiography are adapted simultaneously to a double-stage, large-volume high pressure apparatus, allowing measurements of acoustic velocities under high pressure and temperature. Combined analysis of the ultrasonic velocities and density data enables to determine elastic properties and their pressure derivatives independent of pressure up to lower mantle conditions. In addition, sample pressure can be directly calculated using the measured velocity and density data and finite-strain equations of state and compared with those obtained from a pressure standard adjacent to the sample, providing a means to calibrate the pressure scales currently in use.