Equation of state measurements play a crucial role in understanding the behavior of materials under extreme conditions. Recent advancements have been made by an international team of scientists from Lawrence Livermore National Laboratory (LLNL), Argonne National Laboratory, and Deutsches Elektronen-Synchrotron to improve the reliability of these measurements in a pressure regime previously unattainable in the diamond anvil cell. This breakthrough opens up new possibilities for static compression experiments at unprecedented pressures.
The LLNL team’s development of the toroidal diamond anvil cell has been instrumental in pushing the static pressure limit in condensed matter sciences. However, to further advance the field, a new sample configuration was necessary. Static compression experiments to pressures exceeding 300 GPa are extremely challenging, often resulting in an imperfect compression environment. The introduction of a new sample package has addressed this issue, leading to enhanced equation of state data quality.
In the new sample package, scientists microfabricated a sample in a 10-step process within a tiny sample chamber of approximately 6 µm in diameter, comparable to 20 times smaller than a human hair’s width. The target material is embedded in a soft metal capsule, serving as a pressure-transmitting medium. This uniform capsule ensures the stress is evenly distributed around the sample material during compression, crucial for reliable equation-of-state measurements. The use of a soft metal capsule has proven effective, even at a micron scale.
The experiments were carried out at Argonne National Laboratory Sector 16 HPCAT and Deutsches Elektronen-Synchrotron PETRA-III. The team tested the methodology using molybdenum with a copper pressure-transmitting medium. However, the versatility of this sample package allows for broader applications across various materials and disciplines. LLNL scientist Claire Zurkowski, the first author of the paper, emphasized that this work is only the beginning of sample-package microfabrication in the toroidal diamond anvil cell.
The successful development of this new sample configuration marks a significant step towards optimized static compression experiments at multi-megabar conditions. This advancement provides complementary data to gas-gun and NIF experiments conducted at LLNL. The ability to reliably calibrate equations of state at pressures exceeding two times the current limits opens up new avenues for research in physics, chemistry, and planetary science materials.
The groundbreaking work by the international team of scientists from LLNL, Argonne National Laboratory, and Deutsches Elektronen-Synchrotron represents a major advancement in equation of state measurements. The innovative sample configuration developed for the toroidal diamond anvil cell has the potential to revolutionize static compression experiments at extreme pressures. This research paves the way for further exploration and understanding of materials under conditions previously unexplored.
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