Boron phosphide (BP) structure, equation of state, specific heat, phase transitions

2005 ◽  
pp. 1-4
Author(s):  
Keyword(s):  
Phase Transitions ◽  
Equation Of State ◽  
Specific Heat ◽  
Structure Equation ◽  
Boron Phosphide

A Rational Equation of State for Water and Water Vapor in the Critical Region

1964 ◽  
Vol 86 (3) ◽  
pp. 320-326 ◽  
Author(s):  
E. S. Nowak
Keyword(s):  
Water Vapor ◽  
Equation Of State ◽  
Thermodynamic Properties ◽  
Specific Heat ◽  
Critical Point ◽  
Critical Region ◽  
Constant Pressure ◽  
Parametric Equation ◽  
Enthalpy And Entropy ◽  
Specific Volumes

A parametric equation of state was derived for water and water vapor in the critical region from experimental P-V-T data. It is valid in that part of the critical region encompassed by pressures from 3000 to 4000 psia, specific volumes from 0.0400 to 0.1100 ft3/lb, and temperatures from 698 to 752 deg F. The equation of state satisfies all of the known conditions at the critical point. It also satisfies the conditions along certain of the boundaries which probably separate “supercritical liquid” from “supercritical vapor.” The equation of state, though quite simple in form, is probably superior to any equation heretofore derived for water and water vapor in the critical region. Specifically, the deviations between the measured and computed values of pressure in the large majority of the cases were within three parts in one thousand. This coincides approximately with the overall uncertainty in P-V-T measurements. In view of these factors, the author recommends that the equation be used to derive values for such thermodynamic properties as specific heat at constant pressure, enthalpy, and entropy in the critical region.

HIGH RESOLUTION CALORIMETRIC STUDIES AT PHASE TRANSITIONS OF ALKYLCYANOBIPHENYL LIQUID CRYSTALS CONFINED TO SUBMICRON SIZE CYLINDRICAL CAVITIES

1995 ◽  
Vol 09 (18n19) ◽  
pp. 2247-2283 ◽  
Author(s):  
DANIELE FINOTELLO ◽  
GERMANO S. IANNACCHIONE
Keyword(s):  
Phase Transitions ◽  
Liquid Crystals ◽  
High Resolution ◽  
Specific Heat ◽  
Pore Wall ◽  
Isotropic Phase ◽  
First Order ◽  
Smectic A ◽  
Nematic Director ◽  
Scalar Order Parameter

We review results of a high resolution systematic study of the specific heat for alkyl-cyanobiphenyl liquid crystals confined to the 0.2µm diameter cylindrical pores Anopore membranes. The nematic director alignment at the pore wall is varied from homeotropic to tangential by pore surface treatment. Several phenomena are uncovered by these studies which probed the weakly first order nematic to isotropic, the continuous smectic-A to nematic and the first order smectic-A to isotropic phase transitions. The specific heat is strongly dependent on the nematic director configuration, and confinement effects are remarkably distinct according to the order of the phase transition. The influence of elastic distortions and surface ordering and disordering effects are evident. Despite considerable departures from bulk behavior with regards to specific heat peaks size, rounding and width, and transition temperature shifts, a bulk-like critical behavior appears to be retained. The formation of smectic translational order within the pores is hindered for those liquid crystals that also possess a nematic phase. The average scalar order parameter temperature dependence is extracted from the specific heat results using a simplified Landau-de Gennes type of model, and is shown to be consistent with nuclear magnetic resonance results.

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.

Magnetic behavior of the metal organic framework [(CH3)2NH2]Co(HCOO)3

RSC Advances ◽  
2015 ◽  
Vol 5 (47) ◽  
pp. 37818-37822 ◽  
Author(s):  
K. Vinod ◽  
C. S. Deepak ◽  
Shilpam Sharma ◽  
D. Sornadurai ◽  
A. T. Satya ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Phase Transitions ◽  
Specific Heat ◽  
Single Crystals ◽  
Metal Organic Framework ◽  
Magnetic Behavior ◽  
Metal Organic ◽  
Organic Framework

In this study we examine the phase transitions in single crystals of [(CH3)2NH2]Co(HCOO)3, using magnetization and specific heat measurements as a function of temperature and magnetic field.

Analysis of the Specific Heat of Ru Doped LiKSO4 Close to Phase Transitions

2018 ◽  
Vol 56 (3) ◽  
pp. 462-465 ◽  
Author(s):  
H. Yurtseven ◽  
D. V. Tirpanci ◽  
H. Karacali
Keyword(s):  
Phase Transitions ◽  
Specific Heat
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