Evaluations of pressure-transmitting media for cryogenic experiments with diamond anvil cell

TL;DR

This study evaluates fourteen pressure-transmitting media for cryogenic diamond anvil cell experiments at low temperatures and high pressures, identifying helium, argon, and nitrogen as the most suitable for maintaining hydrostatic conditions.

Contribution

It provides a systematic comparison of various media's hydrostaticity at cryogenic temperatures, highlighting the most effective options for high-pressure low-temperature experiments.

Findings

Helium, argon, and nitrogen show minimal nonhydrostatic effects at 77 K.

Most media develop nonhydrostatic effects below room temperature.

Helium, argon, and nitrogen are suitable for cryogenic high-pressure experiments.

Abstract

The fourteen kinds of pressure-transmitting media were evaluated by the ruby fluorescence method at room temperature, 77 K using the diamond anvil cell (DAC) up to 10 GPa in order to find appropriate media for use in low temperature physics. The investigated media are a 1:1 mixture by volume of Fluorinert FC-70 and FC-77, Daphne 7373 and 7474, NaCl, silicon oil (polydimethylsiloxane), Vaseline, 2-propanol, glycerin, a 1:1 mixture by volume of $n$-pentane and isopentane, a 4:1 mixture by volume of methanol and ethanol, petroleum ether, nitrogen, argon and helium. The nonhydrostaticity of the pressure is discussed from the viewpoint of the broadening effect of the ruby $R_1$ fluorescence line. The $R_1$ line basically broadens above the liquid-solid transition pressure at room temperature. However, the nonhydrostatic effects do constantly develop in all the media from the low-pressure region at low temperature. The relative strength of the nonhydrostatic effects in the media at the low temperature region is discussed. The broadening effect of the ruby $R_1$ line in the nitrogen, argon and helium media are significantly small at 77 K, suggesting that the media are more appropriate for cryogenic experiments under high pressure up to 10 GPa with the DAC. The availability of the three media was also confirmed at 4.2 K.