scholarly journals Surface Properties of Al–Fe–Si Liquid Alloy Using Thermodynamic Database

2020 ◽  
Vol 6 (2) ◽  
pp. 10-19
Author(s):  
U. Mehta ◽  
S. K. Yadav ◽  
I. Koirala ◽  
D. Adhikari
Keyword(s):  
Surface Tension ◽  
Ternary Alloy ◽  
Binary Systems ◽  
Excess Free Energy ◽  
Surface Concentration ◽  
Liquid Alloys ◽  
Free Energies ◽  
Temperature Dependent ◽  
Excess Surface ◽  
Good Agreement

Temperature-dependent interaction parameters for excess free energies of mixing of sub-binary systems of Al-Fe-Si ternary liquid alloys were optimised using the experiment data in the frame of Redlich-Kister (R-K) polynomials. These optimised parameters were then used to compute the partial excess free energy of sub-binary and ternary liquid alloys. The surface tension and surface concentration of sub-binary and the ternary liquid alloys were computed using Butler equation. The temperature dependent coefficients of R-K polynomials for excess surface tensions of the sub-binary systems were optimised which were then used to estimate the surface tension of ternary alloy using Chou, Kohler and Toop modelling equations at temperatures 1773, 1873, 1973 and 2073 K. The surface tension of the ternary alloy obtained using aforementioned models were found to be in good agreement from Fe and Al corners but some deviations were observed from Si corner.

scholarly journals Microscopic and Surface Properties of K-Na Liquid Alloys

2013 ◽  
Vol 4 ◽  
pp. 40-45
Author(s):  
I. Koirala ◽  
B. P. Singh ◽  
I. S. Jha
Keyword(s):  
Surface Properties ◽  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Energy Parameter ◽  
Surface Concentration ◽  
Liquid Alloys ◽  
Range Order Parameter ◽  
Temperature Dependent ◽  
Long Wavelength

The deviation from ideal mixture behavior and concentration dependent symmetry in the microscopic and surface properties of K-Na liquid alloy is investigated within a simple statistical model. The concentration dependent of microscopic functions(concentration fluctuation in the long wavelength limit, Warren-Cowley short range order parameter) and surface properties(surface concentration and surface tension) has got special attention to show a tendency of like atom pairing in the mixture. The theoretical analysis reveals that energy parameter is temperature dependent, K-Na alloys is of weakly interacting system and K-atoms segregates on the surface of K-Na liquid alloys at bulk concentration of Na.The Himalayan Physics Vol. 4, No. 4, 2013 Page: 40-45 Uploaded date: 12/23/2013 

scholarly journals Investigation on thermo-physical properties of liquid In-Tl alloy

BIBECHANA ◽  
2021 ◽  
Vol 18 (1) ◽  
pp. 149-158
Author(s):  
I B Bhandari ◽  
N Panthi ◽  
I Koirala
Keyword(s):  
Surface Tension ◽  
Complex Formation ◽  
Statistical Model ◽  
Physical Properties ◽  
Formation Model ◽  
Temperature Dependent ◽  
Thermo Physical Properties ◽  
Theoretical Results ◽  
Mixing Behaviour ◽  
Good Agreement

This research explores mixing behaviour of liquid In – Tl system through thermodynamic and the structural properties on the basis of Complex Formation Model. The properties like surface tension and viscosity have been analyzed through simple statistical model and Moelwyn – Hughes equation. The interaction parameters are found to be positive, concentration independent and temperature dependent. Theoretical results are in a good agreement with the corresponding literature data which support homo-coordinating tendency in the liquid In-Tl alloy. BIBECHANA 18 (2021) 149-158

scholarly journals Effects of surface coordination of atoms on the surface properties of Cd-X (X= Ga, Zn) liquid alloys

2018 ◽  
Vol 2 ◽  
pp. 90-95
Author(s):  
Ishwar Koirala
Keyword(s):  
Surface Tension ◽  
Statistical Mechanics ◽  
Surface Properties ◽  
Order Parameter ◽  
Surface Concentration ◽  
Concentration Fluctuations ◽  
Liquid Alloys ◽  
Model Surface ◽  
Mechanics Model ◽  
Effect Of Surface

We have investigated the effect of surface coordination of atoms on the surface properties of Cd-Ga and Cd-Zn liquid alloys by varying their surface coordination fractions using statistical mechanics model. Surface tension and surface concentration did not have significant effect on the calculation of both surface tension and surface concentration of two alloys. The computation of the concentration fluctuations at the surface revealed that it was sensitive to the surface coordination fractions of both segregating systems. In those alloys we found that the computation of the Warren-Cowley short rang order parameter was influenced by the surface coordination fractions.

EXCESS VOLUMES, VAPOR PRESSURES, AND RELATED THERMODYNAMIC PROPERTIES OF THE SYSTEM ACETONE–CHLOROFORM–BENZENE, AND ITS COMPONENT BINARY SYSTEMS

1966 ◽  
Vol 44 (10) ◽  
pp. 1183-1189 ◽  
Author(s):  
A. N. Campbell ◽  
E. M. Kartzmark ◽  
R. M. Chatterjee
Keyword(s):  
Binary Systems ◽  
Excess Entropy ◽  
Excess Free Energy ◽  
Heat Of Mixing ◽  
Vapor Pressures ◽  
Free Energies ◽  
Volume Changes ◽  
Heats Of Mixing ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing

The volume changes on mixing of the three binary mixtures, acetone–chloroform, benzene–chloroform, acetone–benzene, and the ternary mixture, acetone–chloroform–benzene, and their molar refractivities and viscosities, were determined.Determinations of total and partial vapor pressures were made. The systems acetone–chloroform and benzene–chloroform show negative deviations from Raoult's law. The system acetone–benzene shows positive deviations.The excess Gibbs free energies of mixing have been calculated for all systems. By combining these data with previously measured heats of mixing (1), the excess entropy has also been calculated. The curves representing zero excess volume, zero heat of mixing, zero excess free energy of mixing, and zero excess viscosity as functions of composition in the ternary system do not coincide. It, therefore, must be concluded that they result from compensating effects and do not represent ideality.

scholarly journals Chemical Ordering of Ag-Au Alloys in the Molten State

2018 ◽  
Vol 22 (2) ◽  
pp. 191-201 ◽  
Author(s):  
Ishwar Koirala
Keyword(s):  
Surface Tension ◽  
Wave Length ◽  
Energy Parameter ◽  
Surface Concentration ◽  
Heat Of Mixing ◽  
Temperature Dependent ◽  
Chemical Ordering ◽  
Energy Of Mixing ◽  
Free Energy Of Mixing ◽  
Structural Behaviors

Simple statistical model has been used to report the thermodynamic, structural, transport and surface properties of liquid Ag-Au alloys at 1350K. In thermodynamic properties we have studied the free energy of mixing, heat of mixing, entropy of mixing and the chemical activity of both components of the alloys. For the structural investigation, our study includes concentration fluctuation in long wave length limit and Warren-Cowley short range order parameter. Viscosity and diffusivity of the alloys have been studied to understand transport properties. The surface behavior has been analyzed by computing surface concentration and surface tension of the alloys. The structural behaviors of the alloys are found to be symmetric with respect to concentrations of the species. The computed results are in good agreement with experimental data. Positive deviation of viscosity isotherms from linear law is observed. Surface tension of the alloys is found to be smaller than ideal values throughout bulk concentration of silver. For all theoretical analysis, concentration independent energy parameter takes important role, which is found to be temperature dependent and finally analysis confirms that presented alloy is hetero-coordinated.Journal of Institute of Science and Technology Volume 22, Issue 2, January 2018, Page: 191-201

scholarly journals A simple theory of mixtures for the study of the temperature dependence of thermo-structural properties of Al-Ga liquid alloy

2020 ◽  
Vol 31 (3) ◽  
pp. 87-100
Author(s):  
Kritika Khanal ◽  
◽  
Shashit Kumart Yadav ◽  
Devendra Adhikari ◽  
◽  
...  
Keyword(s):  
Free Energy ◽  
Structural Properties ◽  
Excess Free Energy ◽  
Simple Theory ◽  
Temperature Dependent ◽  
Long Wavelength ◽  
Energy Of Mixing ◽  
Theory Of Mixtures ◽  
Free Energy Of Mixing ◽  
Good Agreement

A simple theory of mixtures for symmetric alloys was used to study the thermodynamic and structural properties of the Al-Ga alloy in the liquid state at 1023 K. The computed thermodynamic properties are in a very good agreement with the observed values and show that the alloy is weakly interacting. The computed structural properties show that the Al-Ga alloy is segregating in nature which is in agreement with the observed values. The excess free energy of mixing, activity of monomers and concentration fluctuation in the long wavelength limit was extrapolated to higher temperatures by optimising the temperature dependent parameters. As the temperature increases, the behaviour of the alloy shifts towards the ideality.

scholarly journals Transport and Surface Properties of Molten Cd-Zn Alloys

2015 ◽  
Vol 19 (1) ◽  
pp. 14-18 ◽  
Author(s):  
I Koirala ◽  
B.P. Singh ◽  
I.S. Jha
Keyword(s):  
Surface Tension ◽  
Statistical Theory ◽  
Surface Properties ◽  
Surface Concentration ◽  
Liquid Alloys ◽  
Negative Deviation ◽  
Mixing Parameters ◽  
Weak Phase ◽  
Thermo Physical Properties ◽  
Zn Alloys

Simple statistical theory has been used to report the thermo-physical properties of mixing in liquid Cd-Zn alloys. The energetic of mixing in liquid alloys has been analyzed through the study of surface properties (surface tension, surface concentration) and transport properties (diffusivity, viscosity). Negative deviation from Raoultian behaviour has been observed in the computed mixing parameters (viscosity, surface tension) of the alloys. The computed results support a weak phase-separation tendency in molten Cd-Zn system.Journal of Institute of Science and Technology, 2014, 19(1): 14-18

Partition Coefficients of Methylated DNA Bases Obtained from Free Energy Calculations with Molecular Electron Density Derived Atomic Charges.

2018 ◽  
Author(s):  
Alejandro Lara ◽  
Maximiliano Riquelme ◽  
Esteban Vöhringer-Martinez
Keyword(s):  
Electron Density ◽  
Partition Coefficients ◽  
Dna Bases ◽  
Atomic Charges ◽  
Free Energies ◽  
Solvation Model ◽  
Minimal Basis ◽  
Methylated Dna ◽  
Implicit Solvation Model ◽  
Good Agreement

<div> <div> <div> <p>Partition coefficients serve in various areas as pharmacology and environmental sciences to predict the hydrophobicity of different substances. Recently, they have been also used to address the accuracy of force fields for various organic compounds and specifically the methylated DNA bases. In this study atomic charges were derived by different partitioning methods (Hirshfeld and Minimal Basis Iterative Stockholder) directly from the electron density obtained by electronic structure calculations in vac- uum, with an implicit solvation model or with explicit solvation taking the dynamics of the solute and the solvent into account. To test the ability of these charges to describe electrostatic interactions in force fields for condensed phases the original atomic charges of the AMBER99 force field were replaced with the new atomic charges and combined with different solvent models to obtain the hydration and chloroform solvation free energies by molecular dynamics simulations. Chloroform-water partition coefficients derived from the obtained free energies were compared to experimental and previously reported values obtained with the GAFF or the AMBER-99 force field. The results show that good agreement with experimental data is obtained when the polarization of the electron density by the solvent has been taken into account deriving the atomic charges of polar DNA bases and when the energy needed to polarize the electron den- sity of the solute has been considered in the transfer free energy. These results were further confirmed by hydration free energies of polar and aromatic amino acid side chain analogues. Comparison of the two partitioning methods Hirsheld-I and Minimal Basis Iterative Stockholder (MBIS) revealed some deficiencies in the Hirshfeld-I method related to nonexistent isolated anionic nitrogen pro-atoms used in the method. Hydration free energies and partitioning coefficients obtained with atomic charges from the MBIS partitioning method accounting for polarization by the implicit solvation model are in good agreement with the experimental values. </p> </div> </div> </div>

scholarly journals Thermodynamics and Intermolecular Interactions of Nicotinamide in Neat and Binary Solutions: Experimental Measurements and COSMO-RS Concentration Dependent Reactions Investigations

2021 ◽  
Vol 22 (14) ◽  
pp. 7365
Author(s):  
Piotr Cysewski ◽  
Maciej Przybyłek ◽  
Anna Kowalska ◽  
Natalia Tymorek
Keyword(s):  
Intermolecular Interactions ◽  
Vibrational Energy ◽  
Perfect Match ◽  
Zero Point ◽  
Heat Capacity Change ◽  
Free Energies ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Capacity Change ◽  
Self Association

In this study, the temperature-dependent solubility of nicotinamide (niacin) was measured in six neat solvents and five aqueous-organic binary mixtures (methanol, 1,4-dioxane, acetonitrile, DMSO and DMF). It was discovered that the selected set of organic solvents offer all sorts of solvent effects, including co-solvent, synergistic, and anti-solvent features, enabling flexible tuning of niacin solubility. In addition, differential scanning calorimetry was used to characterize the fusion thermodynamics of nicotinamide. In particular, the heat capacity change upon melting was measured. The experimental data were interpreted by means of COSMO-RS-DARE (conductor-like screening model for realistic solvation–dimerization, aggregation, and reaction extension) for concentration dependent reactions. The solute–solute and solute–solvent intermolecular interactions were found to be significant in all of the studied systems, which was proven by the computed mutual affinity of the components at the saturated conditions. The values of the Gibbs free energies of pair formation were derived at an advanced level of theory (MP2), including corrections for electron correlation and zero point vibrational energy (ZPE). In all of the studied systems the self-association of nicotinamide was found to be a predominant intermolecular complex, irrespective of the temperature and composition of the binary system. The application of the COSMO-RS-DARE approach led to a perfect match between the computed and measured solubility data, by optimizing the parameter of intermolecular interactions.

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