scholarly journals Experimental equation of state of 11 lanthanide nitrides (NdN to LuN) and pressure induced phase transitions in NdN, SmN, EuN, and GdN

2020 ◽  
Vol 128 (13) ◽  
pp. 135902 ◽  
Author(s):  
Emma Ehrenreich-Petersen ◽  
Morten B. Nielsen ◽  
Martin Bremholm
Keyword(s):  
Phase Transitions ◽  
Equation Of State ◽  
Experimental Equation

scholarly journals Isothermal equation of state and high-pressure phase transitions of synthetic meridianiite (MgSO4·11D2O) determined by neutron powder diffraction and quasielastic neutron spectroscopy

2017 ◽  
Vol 73 (1) ◽  
pp. 33-46 ◽  
Author(s):  
A. Dominic Fortes ◽  
Felix Fernandez-Alonso ◽  
Matthew Tucker ◽  
Ian G. Wood
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Equation Of State ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Neutron Powder Diffraction ◽  
Bulk Liquid ◽  
Icy Satellites ◽  
Neutron Spallation Source ◽  
Quasielastic Neutron

We have collected neutron powder diffraction data from MgSO4·11D2O (the deuterated analogue of meridianiite), a highly hydrated sulfate salt that is thought to be a candidate rock-forming mineral in some icy satellites of the outer solar system. Our measurements, made using the PEARL/HiPr and OSIRIS instruments at the ISIS neutron spallation source, covered the range 0.1 < P < 800 MPa and 150 < T < 280 K. The refined unit-cell volumes as a function of P and T are parameterized in the form of a Murnaghan integrated linear equation of state having a zero-pressure volume V 0 = 706.23 (8) Å3, zero-pressure bulk modulus K 0 = 19.9 (4) GPa and its first pressure derivative, K′ = 9 (1). The structure's compressibility is highly anisotropic, as expected, with the three principal directions of the unit-strain tensor having compressibilities of 9.6 × 10−3, 3.4 × 10−2 and 3.4 × 10−3 GPa−1, the most compressible direction being perpendicular to the long axis of a discrete hexadecameric water cluster, (D2O)16. At high pressure we observed two different phase transitions. First, warming of MgSO4·11D2O at 545 MPa resulted in a change in the diffraction pattern at 275 K consistent with partial (peritectic) melting; quasielastic neutron spectra collected simultaneously evince the onset of the reorientational motion of D2O molecules with characteristic time-scales of 20–30 ps, longer than those found in bulk liquid water at the same temperature and commensurate with the lifetime of solvent-separated ion pairs in aqueous MgSO4. Second, at ∼ 0.9 GPa, 240 K, MgSO4·11D2O decomposed into high-pressure water ice phase VI and MgSO4·9D2O, a recently discovered phase that has hitherto only been formed at ambient pressure by quenching small droplets of MgSO4(aq) in liquid nitrogen. The fate of the high-pressure enneahydrate on further compression and warming is not clear from the neutron diffraction data, but its occurrence indicates that it may also be a rock-forming mineral in the deep mantles of large icy satellites.

High-pressure phase transitions and equation of state of the III-V compound InAs up to 27 GPa

1985 ◽  
Vol 31 (11) ◽  
pp. 7344-7348 ◽  
Author(s):  
Yogesh K. Vohra ◽  
Samuel T. Weir ◽  
Arthur L. Ruoff
Keyword(s):  
High Pressure ◽  
Phase Transitions ◽  
Equation Of State ◽  
High Pressure Phase ◽  
Pressure Phase
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