Reassessment of a bond correction method for in situ ultrasonic interferometry on elastic wave velocity measurement under high pressure and high temperature

A new bond correction method for simultaneous elastic wave velocity measurement of in situ synchrotron X-ray technique and ultrasonic interferometry combined with a Kawai type multi-anvil apparatus is developed to measure elastic wave velocity precisely. The new method was validated using data from the literature and new elastic constant data of gold obtained under high pressure and high-temperature conditions. Elastic wave velocities corrected using the new method show lower values than those obtained without bond correction and using the conventional method, which show good agreement with datasets by in situ Brillouin scattering measurement and ab initio calculation. When the sample length is 1 mm under ambient conditions, the corrected <i>V</i>_P and <i>V</i>_S became 3.7% and 1.6% lower, respectively, than values obtained without bond correction under 12 GPa and 900 K. Results show that correcting the bond effect is extremely important, especially when the sample length is less than 1 mm.