P–V–Tequation of state of synthetic mirabilite (Na₂SO₄·10D₂O) determined by powder neutron diffraction

Abstract

Neutron powder diffraction data have been collected from Na2SO4·10D2O (the deuterated analogue of mirabilite), a highly hydrated sulfate salt that is thought to be a candidate rock‐forming mineral in some icy satellites of the outer solar system. These measurements, made using the OSIRIS instrument on the ISIS neutron spallation source, covered the range 0.1 < P < 545 MPa and 150 < T < 270 K. The refined unit‐cell volumes as a function of pressure and temperature are parameterized in the form of a Birch–Murnaghan third‐order equation of state, and the anisotropic linear incompressibilities are represented in terms of the elastic strain tensor. At 270 K, the bulk modulus K0,270 = 19.6 (1) GPa, its first pressure derivative ∂K/∂P = 5.8 (5) and its temperature dependence ∂K/∂T = −0.0175 (6) GPa K−1. The stiffest direction at 270 K, with a linear bulk modulus of ∼82 GPa, is coincident with the twofold axis of this monoclinic crystal. Of the remaining two principal directions, the most compressible (K≃ 44 GPa) is roughly aligned with the c axis, and the intermediate value (K≃ 59 GPa) is therefore approximately collinear with a*. With the aid of additional published data, a number of other important thermodynamic quantities have been derived, including the Grüneisen and Anderson–Grüneisen parameters, and the volume and enthalpy of melting along the high‐pressure melting curve. Additional data obtained during this work, concerning the elastic properties of deuterated ice IV, are also presented.

On the crystal structures and phase transitions of hydrates in the binary dimethyl sulfoxide–water system

“…Rasmussen & MacKenzie (1968) noted that salts appear to retard or prevent the trihydrate eutectic crystallization. Equally, the melting point of the trihydrate may exhibit a negative or parabolic pressure dependence such that a lower hydrate is able to become the liquidus phase at high pressure; this occurs in both MgSO 4 Á11H 2 O and Na 2 SO 4 Á-10H 2 O (Fortes et al, 2013(Fortes et al, , 2017. Cansell et al (1992) examined pure DMSO and a 32 mol% DMSO-water mixture (close to the dihydrate composition) up to 20 GPa in a diamond anvil cell using Raman spectroscopy.…”

The compression behavior of blödite at low and high temperature up to ∼10 GPa: Implications for the stability of hydrous sulfates on icy planetary bodies

“…A comparison of the compression behavior of blödite with other of Na-Mg sulfates allows further predictions regarding the stability of hydrous minerals in the interior of icy bodies. High pressure of mirabilite, the sodium sulphate decahydrate (Na 2 SO 4 ·10 H 2 O), was studied by Fortes et al (2013), who determined the bulk modulus by using powder neutron diffraction data at 270 K being equal to 19.6 (1) GPa, its first pressure derivative δK/δP = 5.8(5), and its temperature dependence δK/δT = -0.0175 (6) GPa K -1 . The high pressure behavior of epsomite (MgSO 4 ·7H 2 O) was studied by Fortes et al (2006), who determined a bulk modulus of 21.5(4) GPa and a K' = 5.5 along the isotherm of 290 K. Thermogravimetric analyses of mirabilite and epsomite (Prieto et al 2000) showed that mirabilite dehydrates in two steps at 310 and 333 K, whereas epsomite loses water in three steps at 319, 324 and 347 K.…”

“…Although many studies have focused on the stability of sulfates at high pressure and temperature (Comodi et al 2008(Comodi et al , 2012Fortes et al 2013;Hawthorne 1985;Stoilova and Wildner 2004;Vance 2007;Yamamoto et al 196;Gromnitskaya et al 2013), only few studies were devoted to layered double sulfates such as blödite, mostly of which dealing with crystallographic aspects at ambient pressures (Hawthorne 1985;Stoilova and Wilder, 2004).…”

Geophysical and geochemical controls on abiotic carbon cycling on Earth-like planets

“…Several equations of state are considered depending on the material: a third-order Birch-Murnaghan equation of state , a power law , and for high-pressure phases of ice, a temperature-dependent equation . A database of planetary materials and equation-of-state parameters is provided with the code and includes data from for α-(bcc)Fe, MgSiO 3 , (Mg,Fe)SiO 3 , high-pressure H 2 O, C (graphite), and SiC; Dubrovinsky et al (2000) for ϵ-Fe; W. W. for liquid Fe; Fei et al (1995) for FeS IV; for FeS VII; for MgO; for SiO 2 ; for Mg 2 SiO 4 ; for (Mg,Fe) 2 SiO 4 ; Duffy, Meade, et al (1995) for Mg(OH) 2 ; Tyburczy et al (1991) for serpentine; for antigorite; for lizardite; Fortes et al (2013) for Na 2 SO 4 •10H 2 O; for MgSO 4 •7H 2 O; for liquid H 2 O and its ices Ih, II, III, V, and VI; Frank et al (2013) for H 2 O ice VII; Fortes et al (2003) for NH 3 •2H 2 O I; for NH 3 •2H 2 O IIa; and for NH 3 •2H 2 O liquid. A typical grid comprises 10 4 zones.…”