Nonhydrostatic compression of elastically anisotropic polycrystals. I. Hydrostatic limits of 4:1 methanol-ethanol and paraffin oil

Abstract

The compression of a foil of Cu 3 Au in 4:1 methanol-ethanol and paraffin oil pressure-transmitting media has been studied by energy-dispersive x-ray diffraction in a diamond-anvil cell. Line shifts and line profiles are used to analyze elastic and plastic strains. The increasing viscosity of 4:1 methanol-ethanol causes departures from hydrostatic conditions starting around 7 GPa even while the medium is in a liquid state. The glass transitions in the range 5-7 GPa for paraffin oil and 12-13 GPa for 4:1 methanol-ethanol cause a volume incompressibility and discontinuity followed by isotropic compression behavior. The hydrostatic limit of a liquid with respect to a polycrystalline sample may lie at pressures considerably below the pressure of solidification. For nonideal powders, even small departures from nonhydrostatic conditions of the pressure transmitting medium, often termed quasihydrostatic, can have a strong influence on the compression behavior.

Raman spectroscopy of open‐ended Single Wall Carbon Nanotubes under pressure: effect of the pressure transmitting medium

“…The freezing pressure of paraffin oil is around 5 GPa but it is possible to have shear strain for much lower pressures [34]. We observe a change of slope in TM shift under pressure in paraffin oil around 3 GPa.…”

“…The maximum pressure for good hydrostaticity using paraffin oil is around 4-5 GPa [34]. For argon and 4 :1 methanol ethanol this maximum pressure is around 10 GPa [35].…”

Synthesis of a predicted layered LiB via cold compression

“…The (002) peak diminished upon decompression and could not be detected at 2.1 GPa in the loading with the H 2 pressure medium. The reflection could not be associated with any of the known phases in the oil/Ar/H 2 pressure media 39,53,54 or the Fe/Re gasket. The derived LiB 1D y phases are clearly not responsible for the peak either, as the distortions cause an upshift of the dominant (100) peak and appearance of minor peaks at considerably larger angles (Fig.…”

High pressure X-ray diffraction study of all Fe–Sn intermetallic compounds and one Fe–Sn solid solution

“…19. Otto et al [55] and Sandberg and Sundqvist [56] reported that the glass transitions in 4:1 methanol-ethanol and silicone oil (1cSt) occur at 12-13 and 1.4 GPa, respectively. The hydrostatic limit of the 4:1 methanol-ethanol mixture lies considerably below the pressure of solidification [55].…”

“…Otto et al [55] and Sandberg and Sundqvist [56] reported that the glass transitions in 4:1 methanol-ethanol and silicone oil (1cSt) occur at 12-13 and 1.4 GPa, respectively. The hydrostatic limit of the 4:1 methanol-ethanol mixture lies considerably below the pressure of solidification [55]. Some part of the deviation from a simple equation of state may also be attributed to the pressure gradient in the sample chamber, so that the pressure at the sample and the measured pressure at the ruby position may differ above the liquid-glass transition.…”