What did the scientists discover?
Pressure processing is a fast and efficient method for materials discovery and property manifestation. Upon application of pressure, soft graphite transforms to superhard diamond, while insulting sulfur turns a superconductor. Unfortunately, unlike diamond that remains stable at ambient conditions, most high-pressure phases can not be preserved upon release of pressure. The desire to harvest metastable materials and exploit their properties for real-world application is the motivation behind a recent paper from the research group of University of Florida professor Charles Cao, appearing in the journal Science this month. In collaboration with CHEXS scientists, the team combined nanocrystal-based designer solids with controlled pressure processing and recovered high-pressure metastable phases to ambient conditions. Beyond the technological breakthrough, the team also identified the mechanisms that allowed them to retain stability of high-pressure phases, including the interplay between nanocrystals and surface-coating molecules, and the role of the 3D inter-connected nanocrystal architecture.
Why is this important? What are the broader impacts of this work?
This new solid-solid transition pathway provides a design principle for controlled fabrication of a new generation of advanced materials. Unlike historical “trial-and-error” materials discovery, pressure-enabled discovery involves design, fabrication, and assembly of nanocrystals with desired chemical compositions and surface molecular decoration. Pressure-engineering of designer solids creates a metastable materials with structure and properties made-to-order, formed under pressure and harvested at ambient conditions, enabling real-world use of new materials for scientific innovation and technological development.
Why did this research need CHESS?
This groundbreaking work was supported by a collaboration between the PI an collaborators and CHEXS scientist Zhongwu Wang, spanning many years, across the former CHESS “B-line” beamline and the new CHEXS HPBio facilities. This work was enabled by custom diamond anvil cells with large opening angles for simultaneous SAXS / WAXS measurements, and by in-situ spectroscopy techniques deployed at CHESS to complement the information gleaned from x-ray scattering, enabling multi-modal measurements during high-pressure materials processing.
How was the work funded?
This research conducted jointly by a group of scientists at U. Florida and Cornell U. was supported by the National Science Foundation (NSF) under awards of DMR-1829070, DMR1710509, DMR1309798, DMR-1332208.
Making the most of metastability
Wendy L. Mao and Yu Lin
Science 377, 6608, 814-815 (2022); https://doi.org/10.1126/science.add5433
Nanocrystals with metastable high-pressure phases under ambient conditions
T Xiao, Y Nagaoka, X Wang, T Jiang, D LaMontagne, Q Zhang, C Cao, X Diao, J Qiu, Y Lu, Z Wang and Y. Charles Cao
Science 377, 6608, 870-874 (2022); https://doi.org/10.1126/science.abq7684