Solidification and loss of hydrostaticity in liquid media used for pressure measurements

Abstract

We carried out a study of the pressure dependence of the solidification temperature in nine pressure transmitting media that are liquid at ambient temperature, under pressures up to 2.3 GPa. These fluids are: 1:1 isopentane/n-pentane, 4:6 light mineral oil/n-pentane, 1:1 isoamyl alcohol/n-pentane, 4:1 methanol/ethanol, 1:1 FC72/FC84 (Fluorinert), Daphne 7373, isopentane, and Dow Corning PMX silicone oils 200 and 60,000 cst. We relied on the sensitivity of the electrical resistivity of Ba(Fe1-xRux)2As2 single crystals to the freezing of the pressure media, and crosschecked with corresponding anomalies observed in the resistance of the manganin coil that served as the ambient temperature resistive manometer. In addition to establishing the Temperature-Pressure line separating the liquid (hydrostatic) and frozen (non-hydrostatic) phases, these data permit rough estimates of the freezing pressure of these media at ambient temperature. This pressure establishes the extreme limit for the medium to be considered hydrostatic. For higher applied pressures the medium has to be treated as non-hydrostatic.2

Probing Local Pressure Environment in Anvil Cells with Nitrogen-Vacancy (N-V−) Centers in Diamond

“…Besides, Daphne oil 7373 is known to solidify at around 20 kbar. 14,15,23,[45][46][47] This modest critical pressure provides a convenient platform for us to demonstrate the power of our method to study the solidification process.…”

“…11 This discrepancy may be attributed to the uniaxial stress components that arise from the solidification of the pressure media. [11][12][13][14][15] The demanding experimental conditions to reach a high pressure impose a great limitation on the design of the instrument, as well as the available methods for probing pressure distribution in-situ. The traditional way to determine pressure in pressure cells is by the optical spectrum of ruby (Cr doped Al 2 O 3 ).…”

High-pressure developments for resonant X-ray scattering experiments at I16

“…Both methods provide reasonably similar values of pressure up to 4 GPa, from where we observed an underestimation from ruby with respect to the gold gauge. This discrepancy between the two approaches might be the result of a combination of deviatoric stress arising from the solidification of the pressure medium (non-hydrostaticity) (Torikachvili et al, 2015) and the fact that the crystal of ruby and the piece of gold might not be exposed to the same stress due to the pressure gradient along the sample chamber (Mao, 1978). Cooling time of the cell mounted inside the cryostat from ambient to base temperature.…”

Influence of Pressure on the Magnetic Response of the Low-Dimensional Quantum Magnet Cu(H2O)2(C2H8N2)SO4

“…Although diamonds can be utilized, the anvils for this work were SiC with 800 µm diameter culets. A BeCu gasket, with a hole diameter of 290 µm confined the sample, Ruby (Al 2 O 3 ) fluorescence served as a manometer [15,16], and Daphne-7373 was employed as the pressure transmitting fluid [8][9][10][11][12]. The fluorescence spectra, 2, were acquired by a home-made, inexpensive minispectrometer [17].…”

“…The piston pressure cell, primarily constructed from BeCu, was custom-designed and constructed at the University of Florida [5] and used the superconducting transition temperature of Pb as a manometer [6,7] and Daphne-7373 oil as a pressure transmission medium [8][9][10][11][12]. The maximum pressure for this cell is approximately 1.4 GPa, because at higher pressures, the parts of the cell irreversibly deform.…”