scholarly journals Thermodynamic properties of propane and methane hydrates doped with sodium hydroxide

2021 ◽  
Vol 2057 (1) ◽  
pp. 012075
Author(s):  
K V Gets ◽  
R K Zhdanov ◽  
Yu Yu Bozhko ◽  
V R Belosludov
Keyword(s):  
Free Energy ◽  
Thermal Expansion ◽  
Thermodynamic Properties ◽  
Sodium Hydroxide ◽  
Cell Volume ◽  
Thermal Expansion Coefficient ◽  
Density Of States ◽  
Lattice Dynamics ◽  
Helmholtz Free Energy ◽  
Wide Range

Abstract Pure and sodium hydroxide doped with single-component hydrates of methane and propane are studied using molecular and lattice dynamics methods. Vibration density of states and the dependence of Helmholtz free energy on temperature and cell volume are calculated. Dynamic stability of empty and filled by gas sI and sII structures doped with 1 or 2 NaOH molecule is shown in the wide range of temperature values. Comparison of free energy values allows calculating the thermal expansion coefficient and demonstrating the possibility of self-preservation effect in NaOH-doped methane and propane hydrates with ~1.8 and ~1.4 mol% of sodium hydroxide, respectively.

Ab initio study of thermodynamic properties of bulk zinc-blende CdS: Comparing the LDA and GGA

2018 ◽  
Vol 32 (20) ◽  
pp. 1850207 ◽  
Author(s):  
Fatemeh Badieian Baghsiyahi ◽  
Arsalan Akhtar ◽  
Mahboubeh Yeganeh
Keyword(s):  
Free Energy ◽  
Thermal Expansion ◽  
Thermodynamic Properties ◽  
Bulk Modulus ◽  
Internal Energy ◽  
Density Functional ◽  
Helmholtz Free Energy ◽  
Constant Volume ◽  
Grüneisen Parameter ◽  
Zinc Blende

In the present study, we have investigated the phonon and thermodynamic properties of bulk zinc-blende CdS by first-principle calculations within the density functional theory (DFT) and the density functional perturbation theory (DFPT) method using the quasi harmonic approximation (QHA). We calculated the phonon dispersion at several high symmetry directions, density of phonon state, temperature dependence feature of Helmholtz free energy (F), internal energy, bulk modulus, constant-volume specific heat, entropy, coefficient of the volume thermal expansion and Grüneisen parameter estimated with the local density approximation (LDA) and generalized gradient approximation (GGA) for the exchange-correlation potential and compared them with each other. For internal energy, Helmholtz free energy, constant volume heat capacity and phonon entropy the LDA and GGA results are very similar. But, the LDA gives lattice constants that are smaller than GGA while phonon frequencies, bulk modulus and cohesive energies are larger. On the other hand, the results obtained through the GGA approximation for the coefficient of the volume thermal expansion and Grüneisen parameter are larger than those obtained from LDA.

Investigation of the Thermodynamic Properties of Anharmonic Crystals with Defects and Influence of Anharmonicity in Exafs by the Moment Method

1998 ◽  
Vol 12 (02) ◽  
pp. 191-205 ◽  
Author(s):  
Vu Van Hung ◽  
Nguyen Thanh Hai
Keyword(s):  
Thermal Expansion ◽  
Thermodynamic Properties ◽  
Phase Change ◽  
Specific Heat ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Moment Method ◽  
Adiabatic Compressibility ◽  
Relative Displacement ◽  
The Moment

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.

Ion-Electron Interaction Contribution to the Helmholtz Free Energy for Fully Ionized Hydrogen Plasma

2012 ◽  
Vol 229-231 ◽  
pp. 991-994
Author(s):  
Xing Rong Zheng ◽  
Chun Ling Tian ◽  
Na Wu ◽  
Bo Wu ◽  
Xiao Bing Wang
Keyword(s):  
Free Energy ◽  
Low Temperature ◽  
Thermodynamic Properties ◽  
High Pressures ◽  
Helmholtz Free Energy ◽  
Hydrogen Plasma ◽  
Padé Approximant ◽  
Electron Interaction ◽  
Pade Approximant ◽  
Interaction Contribution

The Padé approximation is a very important description of thermodynamic properties of fully ionized hydrogen at high pressures and temperatures. By comparing of several reported Padé approximants via calculation of the ion-electron interaction contribution to the Helmholtz free energy of the fully ionized hydrogen plasma, we find that Padé approximant proposed by Stolzman gives an unphysical odd local minimal appears at low temperature( ), and gradually fade away with the increase of temperature, implying a prominent limit of low temperature. While Chabrier et al. developed a more reasonable Padé approximant for the contribution of ion-electron interaction on the Helmholtz free energy. Analyses on isotherm curves indicate that the thermodynamic properties of the ion-electron interaction contribution to the Helmholtz free energy described by the revised Padé approximant is very stable at all temperatures and pressures without any unphysical effects at low temperatures.

The Chemistry Model of Ion-Ion Interaction Energy of Full Ionized Hydrogen Plasma

2014 ◽  
Vol 989-994 ◽  
pp. 779-782
Author(s):  
Li Shuai Guo ◽  
Xing Rong Zheng ◽  
Zhi Rong Wu
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
High Temperatures ◽  
Helmholtz Free Energy ◽  
Hydrogen Plasma ◽  
Fortran Program ◽  
Quantum Statistical Theory ◽  
Quantum Statistical ◽  
Sensitive Parameters ◽  
Interaction Contribution

The ion-ion interaction contribution to the Helmholtz free energy is one of thermodynamic properties which discribing full ionized hydrogen plasma. Based quantum statistical theory and its simulation results to construct the free energy model of statistical mechanics, it is great significant to understand the properties of full ionized hydrogen plasma under high temperatures and pressures. Using Fortran program, we calculated the isotherms with some sensitive parameters, making comparison between our results and the formers. We find that former formula proposed by Chabrier appears variation at ultra-high temperatures ( > Κ ), implying a prominent limit of low temperature, while we developed a more reasonable formula of the ion-ion interaction contribution to the Helmholtz free energy. Analyses on isotherm curves indicate that the thermodynamic properties of the ion-ion interaction contribution to the Helmholtz free energy described by our approximant is very stable at all temperatures and pressures without any unphysical effects at low temperatures.

Thermodynamic properties and lattice dynamics investigation of LuB2C: experiment and ab initio calculations

2019 ◽  
Vol 21 (44) ◽  
pp. 24684-24694 ◽  
Author(s):  
I. R. Shein ◽  
V. V. Novikov ◽  
S. V. Kuznetsov ◽  
K. V. Ponkratov ◽  
A. V. Matovnikov ◽  
...  
Keyword(s):  
Thermodynamic Properties ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Density Of States ◽  
Lattice Dynamics ◽  
Phonon Dispersion ◽  
Phonon Density ◽  
Phonon Density Of States

The phonon dispersion and phonon density of states of LuB2C (Pbam) show the absence of negative phonon frequencies, i.e. this system is dynamically stable.

Theoretical study of thermodynamic properties for SmAlO3 under the effects of pressure and temperature

2018 ◽  
Vol 32 (23) ◽  
pp. 1850247 ◽  
Author(s):  
Ghulam Mustafa ◽  
Ahmad Afaq ◽  
Najm Ul Aarifeen ◽  
Muhammad Asif ◽  
Jamil Ahmad ◽  
...  
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Bulk Modulus ◽  
Internal Energy ◽  
Debye Temperature ◽  
Density Functional ◽  
Helmholtz Free Energy ◽  
Coefficient Of Thermal Expansion ◽  
Temperature Limit ◽  
Debye Model

In the present paper, we have investigated SmAlO3 for their thermodynamic properties under effect of pressure and temperature by employing density functional theory (DFT) and quasi-harmonic Debye model. The various thermodynamic properties like Bulk Modulus, entropy, internal energy, Helmholtz free energy, Debye temperature, coefficient of thermal expansion, Grüneisen parameter and heat capacities of the ternary alloy are calculated. We found that Bulk Modulus, Debye temperature and Helmholtz free energy have decreasing trend with rise of temperature while their values have increasing behavior with rise of pressure. The internal energy of the system almost remains same with variation in pressure but temperature effectively increasing it. Our results are in good agreement with available data at low-temperature limit.

Measurement Principle of Glass Thermal Expansion Coefficient and Technology Application of DIL402PC Dilatometer

2014 ◽  
Vol 983 ◽  
pp. 251-256
Author(s):  
Yan Hua Sun ◽  
Dong Qing Zhang ◽  
Fei Wu ◽  
Kai Sun
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
It Use ◽  
Standard Samples ◽  
Technology Application ◽  
Wide Range ◽  
System Check ◽  
Coefficient Of Linear Expansion ◽  
Accuracy And Repeatability

The paper introduces the measuring principle of glass thermal expansion coefficient. It expresses the features and advantages of the linear variable differential transformer measuring principle by comparing the thermal expansion coefficient measurement methods analysis. Meanwhile, the paper introduces DIL402PC dilatometer measuring devices and measurement procedures. It use standard samples to execute thermal expansion instrument system check from the accuracy and repeatability. The result shows thermal expansion coefficient of linear expansion instrument bias of DIL402PC dilatometer is within the error range of the theoretical value. The process proves it has a wide range of applications.

scholarly journals Investigation of some basic thermodynamic properties of Na-K alloy

BIBECHANA ◽  
2021 ◽  
Vol 18 (2) ◽  
pp. 1-8
Author(s):  
Rajesh C Malan ◽  
Aditya M Vora
Keyword(s):  
Free Energy ◽  
Thermodynamic Properties ◽  
Local Field ◽  
Alkali Metals ◽  
Helmholtz Free Energy ◽  
Correlation Effect ◽  
The Other ◽  
Pseudopotential Theory ◽  
Local Field Correction ◽  
Energy Components

Investigation of thermodynamic of liquid binary alloys using pseudopotential theory is reported. The potential suggested by Fiolhais et al. with its individual parameters is used for the entire calculation. A transferability of the potential from the solid to liquid medium is achieved for the presently reported binary alloy. The internal energy components, Helmholtz free energy, entropy, and total energy at various proportions of the participating alkali metals are included in the study. The comparison with the other data has been shown in the present article. Exchange and correlation effect is also tested with the help of various local field correction functions. BIBECHANA 18 (2) (2021) 1-8

scholarly journals First-principles investigation of mechanical and thermodynamic properties of nickel silicides at finite temperature -=SUP=-*-=/SUP=-

2018 ◽  
Vol 60 (5) ◽  
pp. 964
Author(s):  
Zhiqin Wen ◽  
Yuhong Zhao ◽  
Hua Hou ◽  
Liwen Chen
Keyword(s):  
Heat Capacity ◽  
Thermal Expansion ◽  
High Temperature ◽  
Thermodynamic Properties ◽  
Thermal Expansion Coefficient ◽  
Debye Temperature ◽  
Expansion Coefficient ◽  
Finite Temperature ◽  
Volumetric Thermal Expansion Coefficient ◽  
Nickel Silicides

AbstractFirst-principles calculations are performed to investigate lattice parameters, elastic constants and 3D directional Young’s modulus E of nickel silicides (i.e., β-Ni_3Si, δ-Ni_2Si, θ-Ni_2Si, ε-NiSi, and θ-Ni_2Si), and thermodynamic properties, such as the Debye temperature, heat capacity, volumetric thermal expansion coefficient, at finite temperature are also explored in combination with the quasi-harmonic Debye model. The calculated results are in a good agreement with available experimental and theoretical values. The five compounds demonstrate elastic anisotropy. The dependence on the direction of stiffness is the greatest for δ-Ni_2Si and θ-Ni_2Si, when the stress is applied, while that for β-Ni_3Si is minimal. The bulk modulus B reduces with increasing temperature, implying that the resistance to volume deformation will weaken with temperature, and the capacity gradually descend for the compound sequence of β-Ni_3Si > δ-Ni_2Si > θ-Ni_2Si > ε-NiSi > θ-Ni_2Si. The temperature dependence of the Debye temperature ΘD is related to the change of lattice parameters, and ΘD gradually decreases for the compound sequence of ε-NiSi > β-Ni_3Si > δ-Ni_2Si > θ-Ni_2Si > θ-Ni_2Si. The volumetric thermal expansion coefficient αV, isochoric heat capacity and isobaric heat capacity C _ p of nickel silicides are proportional to T ^3 at low temperature, subsequently, αV and C _ p show modest linear change at high temperature, whereas C _v obeys the Dulong-Petit limit. In addition, β-Ni_3Si has the largest capability to store or release heat at high temperature. From the perspective of solid state physics, the thermodynamic properties at finite temperature can be used to guide further experimental works and design of novel nickel–silicon alloys.

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