The Sm:YAG primary fluorescence pressure scale

Abstract

[1] Primary pressure determinations involve the measurement of pressure without recourse to secondary standard materials. These measurements are essential for ensuring the accuracy of pressures measured in gasketed high-pressure devices. In this study, the wavelength of optical fluorescence bands and the density of single crystal Sm-doped yttrium aluminum garnet Y 3 Al 5 O 12 (Sm:YAG) have been calibrated as a primary pressure scale up to 58 GPa. Absolute pressures were obtained by integrating the bulk modulus determined via Brillouin spectroscopy with respect to volumes measured simultaneously by X-ray diffraction. A third-order Birch-Murnaghan equation of state of Sm:YAG yields V 0 = 1735.15(26) Å 3 , K T0 = 185(1.5) GPa, and K`= 4.18(5). The accompanied pressure-induced shifts of the fluorescence lines Y1 and Y2 of Sm:YAG were calibrated to the primary pressure, thus creating a highly accurate fluorescence pressure scale. These shifts are described as P = (A/B) * {[1 + (Δλ/λ 0 )] B À 1} with A = 2089.91(23.04), B = À4.43(1.07) for Y1, and A = 2578.22(48.70), B = À15.38(1.62) for Y2 bands, where Δλ = λ À λ 0 , λ and λ 0 are wavelengths in nanometer at pressure and ambient conditions. The sensitivity in the pressure determination of the Sm:YAG fluorescence shift is 0.32 nm/GPa, which is identical to that of the ruby scale. Sm:YAG can be considered elastically isotropic up to 58 GPa, implying insensitivity of the determined pressure to the crystallographic orientation under nonhydrostatic or quasi-hydrostatic conditions. The Sm:YAG fluorescence shift is apparently also independent of crystallographic orientation, in contrast to that of ruby. Since the Y fluorescence band of Sm:YAG is insensitive to temperature changes, this material is highly suitable for the measurement of pressure at elevated temperatures.

Perovskite in Earth’s deep interior

“…2B), consistent with the seismologically determined dP/dT slope of the 660-km boundary (8). This value has been controversial (-0.4 to -3 MPa K -1 ), because precise determination of pressure at high temperature is usually dependent on the P-V-T equation of state of an internal standard, but the accuracy and consistency of the equation of state for various kinds of standards are matters of debate (9).…”

Dynamic compression of copper to over 450 GPa: A high-pressure standard

“…Central to these low-temperature high-pressure studies is the existence of a standard method of determining the stress state being studied. Attempts to develop accurate isothermal absolute-pressure standards using Brillouin scattering and x-ray diffraction have been limited to below 60 GPa [2], and therefore at higher pressures shock Hugoniot data are often used to constrain the low temperature isotherm due to the exact nature of the Rankine-Hugoniot relations, [e.g. 3,4].…”

Extending the single-crystal quartz pressure gauge up to hydrostatic pressure of 19 GPa

“…Pressure gauges based on laser-induced luminescence techniques, e.g. ruby, Sm:SrB 4 O 7 and Sm:YAG (YAG is yttrium aluminium garnet) (Mao et al, 1986;Datchi et al, 1997;Trots et al, 2013), are suitable for spectroscopic studies at room temperature and non-ambient temperatures and are convenient for recording of pressure on short time scales within seconds. On the other hand, internal diffraction standards, e.g.…”