Review: high pressure generation techniques beyond the limit of conventional diamond anvils

ABSTRACT

Current anvil designs and problems associated with various efforts to generate static high pressures beyond the limit of conventional diamond anvil cells (DACs) (∼400 GPa) are reviewed. Pressures of up to 1 TPa have been reported by one research group using the double-stage DAC (ds-DAC) technique, but no other research group has successfully reproduced this high pressure result. Some research groups have used toroidal anvils, achieving pressures of >400 GPa. We have conducted numerous ds-DAC experiments and investigated the problems associated with such experiments. They include problems associated with various pressure scales in the multi-megabar region, difficulties in obtaining reliable X-ray diffraction patterns from micron-sized samples, and physical property measurements of tiny materials that may be harder than diamond. Each of these problems is discussed, following the summary of various experiments.

KEYWORDS:

• Multi-megabar
• ds-DAC
• t-DAC

Acknowledgement

We are also grateful to K. Aoki and H. Kagi for helpful discussions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by JSPS KAKENHI (Grant Nos. 16K05530, 15K13594, 17H02985, 25220712, and 15H05829). The synchrotron radiation experiments were performed at the BL10XU, SPring-8, with approval from the Japan Society for the Promotion of Science Synchrotron Radiation Research Institute (JASRI) (Proposal Nos. 2016B1540, 2017A1743, 2017B1563, 2018A1724, and 2018B1380), and we appreciate great helps of the beamline scientists.