Thermodynamic properties of a S=1 spin-phonon system: specific heat of Fe2+in MgO

1971 ◽  
Vol 4 (16) ◽  
pp. 2583-2592 ◽  
Author(s):  
F B Fidler ◽  
J W Tucker
1964 ◽  
Vol 86 (3) ◽  
pp. 320-326 ◽  
Author(s):  
E. S. Nowak

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.


1998 ◽  
Vol 12 (02) ◽  
pp. 191-205 ◽  
Author(s):  
Vu Van Hung ◽  
Nguyen Thanh Hai

By the moment method established previously on the basis of the statistical mechanics, the thermodynamic properties of a strongly anharmonic face-centered and body-centered cubic crystal with point defect are considered. The thermal expansion coefficient, the specific heat Cv and Cp, the isothermal and adiabatic compressibility, etc. are calculated. Our calculated results of the thermal expansion coefficient, the specific heat Cv and Cp… of W, Nb, Au and Ag metals at various temperatures agrees well with the measured values. The anharmonic effects in extended X-ray absorption fine structure (EXAFS) in the single-shell model are considered. We have obtained a new formula for anharmonic contribution to the mean square relative displacement. The anharmonicity is proportional to the temperature and enters the phase change of EXAFS. Our calculated results of Debye–Waller factor and phase change in EXAFS of Cu at various temperatures agrees well with the measured values.


2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Omid Askari

Chemical composition and thermodynamics properties of different thermal plasmas are calculated in a wide range of temperatures (300–100,000 K) and pressures (10−6–100 atm). The calculation is performed in dissociation and ionization temperature ranges using statistical thermodynamic modeling. The thermodynamic properties considered in this study are enthalpy, entropy, Gibbs free energy, specific heat at constant pressure, specific heat ratio, speed of sound, mean molar mass, and degree of ionization. The calculations have been done for seven pure plasmas such as hydrogen, helium, carbon, nitrogen, oxygen, neon, and argon. In this study, the Debye–Huckel cutoff criterion in conjunction with the Griem’s self-consistent model is applied for terminating the electronic partition function series and to calculate the reduction of the ionization potential. The Rydberg and Ritz extrapolation laws have been used for energy levels which are not observed in tabulated data. Two different methods called complete chemical equilibrium and progressive methods are presented to find the composition of available species. The calculated pure plasma properties are then presented as functions of temperature and pressure, in terms of a new set of thermodynamically self-consistent correlations for efficient use in computational fluid dynamic (CFD) simulations. The results have been shown excellent agreement with literature. The results from pure plasmas as a reliable reference source in conjunction with an alternative method are then used to calculate the thermodynamic properties of any arbitrary plasma mixtures (mixed plasmas) having elemental atoms of H, He, C, N, O, Ne, and Ar in their chemical structure.


1993 ◽  
Vol 07 (01n03) ◽  
pp. 810-813
Author(s):  
N.H. KIM-NGAN ◽  
P.E. BROMMER ◽  
J.J.M. FRANSE

Specific heat and thermal expansion measurements have been performed on Nd1−xLUxMn2 in the temperature range between 1.5K and 300K. Below 10K, anomalies are observed which are ascribed to a spin reorientation of the Nd sublattice. These anomalies are only slightly affected by the substitution of Nd by Lu. Large effects, however, are observed on the magnetic properties of the Mn sublattice. The antiferromagnetic order disappears for x exceeding 0.30. The data are analysed in terms of Grüneisen parameters. In the paramagnetic compound LuMn2, a spin-fluctuation contribution to the thermodynamic properties is observed. In the Nd-containing compounds, distinct contributions from the crystal field acting on the Nd ions can be distinguished. The variation of the magnetic properties of the Mn sublattice with the concentration of Lu is discussed.


2002 ◽  
Vol 80 (1) ◽  
pp. 28-30 ◽  
Author(s):  
N. Wang ◽  
X. J. Han ◽  
B. Wei

2018 ◽  
Vol 941 ◽  
pp. 1378-1383 ◽  
Author(s):  
Yukihiro Kawamura ◽  
Chihiro Sekine ◽  
Kazuyuki Matsubayashi ◽  
Yoshiya Uwatoko ◽  
Takashi Nishioka

We present transport and thermodynamic properties of CeRu2Al10 controlled by pressure in a vicinity of a critical pressure PC ~ 4GPa, where antiferromagnetic ordering disappears. The resistivity under pressure was measured with DC four terminal method and the AC specific heat under pressure was measured by Joule heating type technique. The pressure was applied by cubic-anvil-apparatus and palm-cubic-anvil-apparatus. The results of AC specific heat indicate TN holds at high temperature up to 3.9 GPa but suddenly disappears above this pressure. We confirmed TN from thermodynamic properties. Although CeRu2Al10 is in a Kondo semiconducting ground state at 4 GPa, temperature dependences of electrical resistivity at 4.6 GPa and 5.9 GPa indicate metallic ground state in these pressures. CeRu2Al10 does not show superconductivity down to 0.7 K at 4.6 GPa and 5.9 GPa.


1996 ◽  
Vol 457 ◽  
Author(s):  
Yurii I. Aristov ◽  
Mikhail M. Tokarev ◽  
Gaetano Cacciola ◽  
Giovanni Restuccia ◽  
Gaetano DiMarco ◽  
...  

ABSTRACTHere we present physical and chemical properties of CaCl2/H2O and LiBr/H2O systems confined to nanopores of silica gels. Sorption isobars, isosters and isotherms were measured at temperature 293 – 423K and vapor partial pressure 8–133 mbar. Specific heat of the systems was found as a function of temperature (300 – 400K) and sorbed water content (0 – 53 wt.%). Solidification/melting diagrams were measured over 170 – 320K temperature range at salt concentrations 0–50 wt.%. The results obtained evidenced a significant change in the thermodynamic properties of CaCl2/H2O and LiBr/H2O systems due to confinement to the silica gel micropores.


1975 ◽  
Vol 28 (3) ◽  
pp. 315 ◽  
Author(s):  
HJM Hanley ◽  
RO Watts

Thermodynamic properties of methane in the dense gas and liquid states have been calculated by the method of molecular dynamics. The methane pair interactions were modelled using a spherically symmetric m-6-8 potential, and the most significant three-body and quantum effects were included. Agreement between calculated and experimental values for the energy and pressure is generally good except at low temperatures and high densities. The specific heat at constant volume is also briefly discussed.


2006 ◽  
Vol 508 ◽  
pp. 591-596 ◽  
Author(s):  
Mauro Palumbo ◽  
Daniele Baldissin ◽  
Livio Battezzati ◽  
O. Tassa ◽  
Rainer Wunderlich ◽  
...  

This contribution reports the results of calorimetric measurements of the enthalpy of fusion and liquid specific heat carried out in different laboratories as part of the ground campaign of the Thermolab project. Different equipments and calibration methods have been used and critically evaluated. Thermodynamic calculations using the Thermocalc software have been performed and a comparison has been carried out with the experimental results.


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