Advancements in the field of high-pressure experiments have been crucial for researchers in various scientific disciplines. A recent paper published in the Journal of Applied Physics by a team of scientists from Lawrence Livermore National Laboratory, Argonne National Laboratory, and Deutsches Elektronen-Synchrotron highlighted the development of a new sample configuration that significantly improves the reliability of equation of state measurements in a pressure regime not previously achievable.
The team’s innovative approach allows for high-quality static equation-of-state measurements above 5 million atmospheres, reaching conditions comparable to Neptune’s interior. This breakthrough is made possible by the use of a toroidal diamond anvil cell, a technology developed by LLNL that has pushed the static pressure limit in condensed-matter sciences. However, the key to advancing these experiments further lies in the fabrication of more complex samples.
Static compression experiments that aim to achieve pressures higher than 300 GPa are extremely challenging. The compression environment is often not ideal, leading to potential inaccuracies in the equation of state data. It is crucial to address these challenges in order to obtain reliable results for a wide range of materials.
The new sample package developed by the team addresses these challenges by providing an improved compression environment. By microfabricating a sample package in a 10-step process, the researchers were able to embed the target material in a uniform capsule of soft metal, which serves as a pressure-transmitting medium. This ensures that the stress is evenly distributed around the sample material, leading to more reliable equation-of-state measurements.
The experiments were conducted using the LLNL-designed toroidal diamond anvil cell, which is capable of reaching pressures exceeding 300 GPa. The sample chamber, with a diameter of approximately 6 µm, is incredibly small, making it around 20 times smaller than the width of a human hair. In this compact chamber, the scientists were able to create a sample package that allowed for the accurate measurement of the equation of state.
The team conducted their experiments at Argonne National Laboratory and Deutsches Elektronen-Synchrotron, testing the methodology on molybdenum with a copper pressure-transmitting medium. While the initial focus was on molybdenum, the sample package can be applied to a wide range of materials, making it a versatile tool for high-pressure experiments in various scientific fields.
The development of this advanced sample configuration marks a significant step towards optimized static compression experiments in the multi-megabar pressure range. The data obtained from these experiments not only complements other high-pressure experiments conducted at LLNL but also opens up new possibilities for calibrating the equation of state in physics, chemistry, and planetary science materials.
As LLNL scientist Claire Zurkowski, the lead author of the paper, noted, this work is just the beginning of sample-package microfabrication in the toroidal diamond anvil cell. The team anticipates that this innovative approach will push static equation of state calibrations to new heights, providing valuable insights into the behavior of materials under extreme pressure conditions.
The development of advanced sample configurations for high-pressure experiments is essential for pushing the boundaries of scientific knowledge. By improving the reliability and accuracy of equation of state measurements, researchers can gain a deeper understanding of the behavior of materials under extreme conditions, leading to groundbreaking discoveries in various scientific disciplines.