Partial phase diagram for cerium showing the relevant phase boundaries, the shock Hugoniot (red line), and the solid-solid critical point denoted by CP. 16 The solid arrows indicate the region of the phase diagram examined by the preheated experiments (path 1) and the shock-release experiments (path 2). Experimental values for the transition stress are plotted versus the calculated temperature for preheated experiments (yellow-filled circles) and the shock-release experiments (red-filled triangles). An example wave profile for preheated experiments is shown consisting of a ramp-shock where the peak compressed state is denoted by a B on the shock Hugoniot.
Experimental configurations for preheated (top) and front-surface impact experiments (bottom).
Example of PDV data for probes 1 and 2 (shot 56-08-55) shown as a three-dimensional plot of particle velocity (km/s) vs. time (μs) vs. intensity (shown as a colormap in decibels). Note that the PDV data were not corrected for effects of the LiF optical window. 25 Probe 1 monitored the free-surface of the aluminum baseplate and probe 2 monitored the cerium-LiF interface.
Plot of particle velocity (km/s) versus time (μs) obtained using VISAR for pre-heated transmission experiments (top) and shock-release experiments (bottom). The profiles in the top figure were arbitrarily shifted in time for clarity with the initial sample temperature increasing from right-to-left. The dashed curves were calculated using the multiphase EOS.
Volume compression data ( ) plotted versus longitudinal stress (or pressure) for this work along with reported values obtained from the literature. 16,27,32,33 The solid line represents an empirical fit to the data given by the equation . The solid red triangle indicates shot 56-08-57 where shock-jump was not observed and the solid circle (black) indicates the critical point determined from the empirical fit. The vertical dashed lines indicate the pressure range where the shock jump disappears bounding the critical point.
Atomic volume versus pressure comparing the experimental diamond anvil cell data 16 with the model predictions shown as solid curves. For each higher temperature plotted, the curves have been shifted by 0.2 GPa for clarity.
Relevant experimental parameters and measured/calculated quantities for preheated experiments. Values shown in parentheses were obtained from the multiphase EOS.
Relevant experimental parameters and measured/calculated quantities for front-surface impact experiments. Calculated values were obtained from the multiphase EOS.
Parameters for the equations of state for the individual phases of cerium. Mixing potential parameters are also shown.
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