Static compression experiments over 4 Mbar are rare yet critical for developing accurate fundamental physics and chemistry models relevant to a range of topics, including modeling planetary interiors. Within this project we developed a toroidal diamond anvil geometry, crafted into single crystal diamonds with focused ion beam, with 9 µm culet proved capable of achieving pressures in excess of 5 megabars. The toroidal surface prevents gasket outflow and provides a means to stabilize the central culet. We reached a maximum pressure of ~ 6.15 Mbar using Re as in situ pressure marker, a pressure regime typically accessed only by double-stage diamond anvils and dynamic compression platforms. Moreover, utilizing these anvils for studying various transition metals the designs has proven to be a reliable platform, enabling routine static high-pressure studies in the 3 to 5 megabar pressure regime.
This work supports Lawrence Livermore National Laboratory's stockpile stewardship mission focus area and high-energy-density science core competencies by maintaining Laboratory capabilities at the leading edge of static high-pressure science and providing validated tools for measurement of programmatically important materials. A capability of achieving pressures >5 Mbars while incorporating the exquisite fidelity of Diamond Anvil Cell (DAC) studies is a profound advance for program applications. DAC studies very accurately determine the structure and the thermodynamic state variable of temperature. Extending DAC diffraction to more than double the current conventional DAC pressure range will provide high-fidelity equations of state at highly accurate pressure‒temperature conditions to complement measurements from other platforms (laser, gas gun, and pulsed power).
O'Bannon, E., et al. 2018. "Contributed Review: Culet Diameter and the Achievable Pressure of a Diamond Anvil Cell: Implications for the Upper Pressure Limit of a Diamond Anvil Cell." Review of Scientific Instruments 89, 111501. LLNL-JRNL-752817.
——— . 2018. "Powder Diffraction of Simple Metals at Pressures Greater than 5.0 Mbars." Presentation at iUCR annual meeting, Honolulu, HI. LLNL-PRES-756017.
——— . 2018. "Neptune's Core Pressure in the Palm of Your Hand." PLS Postdoc Symposium. LLNL-POST-752868.
——— . 2019. "Equation of State of Ta to 4.2 Mbars." Presentation at Condensed Matter Section WIP. LLNL-PRES-795465.
——— . 2019, "Ultra High Pressure Studies of FCC and BCC Metals." Poster at AIRAPT, Rio de Janeiro, Brazil. LLNL-POST-784659.
Jenei, Z., et al. 2017 "Stability of the Rhombohedral Phase in Vanadium and Ambient Temperature Compression Curve." 6th Joint Workshop on High Pressure, Planetary and Plasma Physics, Gottingen, Germany. LLNL-PRES-739486.
——— . 2018. "Single Crystal Toroidal Diamond Anvils for High Pressure Experiments Beyond 5 Megabars." Nature Communications 9, 3563. LLNL-JRNL-746958.
——— . 2018. "Toroidal Diamond Anvils for Static Compression Experiments Beyond 5 megabars." Presentation at 7th Joint Workshop on High Pressure, Planetary and Plasma Physics, Berlin, Germany. LLNL-PRES-759735.
——— . 2019. "Single Crystal Toroidal Diamond Anvils for Extreme Conditions Experiments Beyond 5 Megabars." Poster at Board of Governors meeting at LLNL, February 2019. LLNL-POST-768062.
——— . 2019. "Toroidal Diamond Anvils for Static Compression Experiments Beyond 5 Megabars." Presentation at APS March Meeting, Boston, MA. LLNL-PRES-7692422.
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