Sound speed measurements in zirconium using the front surface impact technique

We have performed a series of experiments impacting zirconium samples of varying purity level directly onto lithium fluoride (LiF) windows to determine both the Hugoniot and sound speed as a function of stress up to 70 GPa. This front surface impact (FSI) geometry is useful for determining sound speed in shock-compression experiments because wave interactions are mostly eliminated and multiple sample thicknesses are not needed in each experiment. The experimental results show two kinks in the sound speed which correlate well with the location of the alpha --> omega and omega --> beta transitions, respectively. A rarefaction shock also forms in the release wave in experiments conducted at 31 GPa giving further evidence that this phase transition is being observed.