Sound speed measurements at high pressure and temperature in the Paris-Edinburgh cell*

Accurate values of elastic properties of materials such as the bulk, shear, and Young's moduli are important for designing structures, tools, or other machinery. Additionally, if parts are likely to be subjected to elevated temperatures and/or stress, determining the elastic properties at relevant conditions is required to optimize design. To measure the elastic properties of materials, we conduct in situ ultrasound time-of-flight, X-ray radiography, and mass density measurements as a function of temperature and pressure in a Paris-Edinburgh-style (PE) large volume hydraulic pressure cell at the Advanced Photon Source. Ultrasound time-of-flight is obtained via the pulse-echo method, while X-ray diffraction is used to measure density and pressure, and sample dimensions are determined by X-ray radiography. The PE cell can achieve conditions of up to 7 GPa and 1000 °C. The SonicPy software package is used to analyze the data collected and extract the elastic constants of interest. Recent experimental results on cerium metal will be presented to demonstrate the technique, along with details about efforts to model the pressure cell using the finite element calculation method to assess the pressure environment surrounding the sample.