Shock-induced Bct-bcc Transition And Melting Of Tin Identified By Sound Velocity Measurements

摘要

A direct reverse-impact configuration together with the velocity interferometer system for any reflector was utilized to accurately measure longitudinal and bulk sound velocities of tin under shock compression. Shock-induced bct-bcc transition and melting of tin were identified based on the discontinuity of the longitudinal sound velocity against shock pressure, which were not previously revealed by Hugoniot and wave profile measurements. The transition pressures for bct to bcc phase and bcc to liquid phase were constrained to be ～34 ± 2 and ～39 ± 2 GPa, respectively. The shear modulus and yield strength at loaded shock stresses were extracted from the measured sound velocities. A tentative phase diagram of tin was constructed by available experimental data and thermodynamic calculations, which was consistent with results from diamond anvil cell experiments and inconsistent with those from shock temperature measurements and molecular dynamic simulations.