Study of shock-induced phase transitions in CaF2

  Benny Glam [1]  ,  Arnon Yosef-Hi [2]  ,  Alexander Gefen [1]  ,  Refael Hevroni [2]  
[1] Applied Physics Division, Soreq NRC
[2] Physics Division, NRC Negev

 Fluorite, CaF2 is a model ionic solid and prototypical type in condensed matter physics, undergoing phase transitions to highly coordinated AX2 structure. In this study, the shock-induced phase transitions in CaF2 were investigated by plate impact experiments, carried out with the gas gun at NRC Negev and the powder gun at Soreq NRC. Single-crystal samples in (111) and (100) orientations were shock loaded to pressures between 7 GPa to 45 GPa. The particle velocities were probed by VISAR and PDV. Measurements in samples with different thicknesses allow us to extract the shock velocity and the sound velocity in the compressed material. We observe evidence for a transition to a high-pressure phase, where the phase transition seems to be sensitive to pressure and strain-rate.