Hugoniot temperatures and melting of tantalum under shock compression determined by optical pyrometry

LiF single crystal was used as transparent window (anvil) to tamp the shock-induced free surface expansion of Ta specimen, and the Ta/LiF interface temperature was measured under shock compression using optical pyrometry technique. The shock temperatures and/or melting temperatures of Ta up to similar to 400 GPa were extracted from the observed interface temperatures based on the Tan-Ahrens' model for one-dimensional heat conduction across metal/window ideal interface in which initial melting and subsequent solidification were considered under shock loading. The obtained data within the experimental uncertainties are consistent with the results from high-pressure sound velocity measurements. The temperature of the partial melting on Ta Hugoniot is estimated to be similar to 9700 K at 300 GPa, supported by available results from theoretical calculations. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3204941]