Shock-induced melting of [100] lithium fluoride: Sound speed and Hugoniot measurements to 230 GPa
Although [100] lithium flouride (LiF) is the most widely used optical window material in dynamic compression experiments, its high stress (>100 GPa) shock compression response, including melting, is not well understood. To address this need, we measured wave profiles in plate impact experiments to determine the Hugoniot states and longitudinal sound speeds in [100] LiF crystals shock compressed to 231 GPa. The measured peak states are fitted well by a linear shock velocity-particle velocity relation, providing an accurate determination of the LiF Hugoniot curve to significantly higher stresses than previous experiments. The longitudinal sound speeds show a near linear increase with density compression to 182 GPa. Between 182 GPa and 195 GPa, the sound speed and the longitudinal modulus decrease abruptly, due to shock-induced melting. The increasing sound speeds and moduli at higher stresses suggest that shock compressed LiF is fully liquid at 195 GPa and above, allowing determination of the Gruneisen parameter for liquid LiF. Here, the melt stress determined here differs from that predicted by current multiphase equations of state for LiF. Our results provide important insight into the high stress solid and liquid states of shock compressed LiF and point to the need for an improved multiphase equation of state at high pressures and high temperatures.
- Research Organization:
- Washington State University, Pullman, WA (United States). Inst. for Shock Physics
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA), Office of Defense Programs (DP)
- Grant/Contract Number:
- NA0003957
- OSTI ID:
- 1924540
- Journal Information:
- Physical Review. B, Vol. 107, Issue 1; ISSN 2469-9950
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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