scholarly journals Thermodynamic modeling of the Hf-N system

2018 ◽  
Vol 54 (1) ◽  
pp. 111-118 ◽  
Author(s):  
M. Pang ◽  
Y. Peng ◽  
P. Zhou ◽  
Y. Du
Keyword(s):  
Thermodynamic Modeling ◽  
Composition Range ◽  
Thermodynamic Description ◽  
Electronic Devices ◽  
Cutting Tools ◽  
Phase Diagram Data ◽  
Thermodynamic Quantities ◽  
Materials Development ◽  
Property Data ◽  
Fcc Phase

Hf-N based alloys have been widely used and studied in the fields of electronic devices and cutting tools industry. A thermodynamic description of this system is essential for further materials development. By means of CALPHAD method, a thermodynamic modeling of the Hf-N system was carried out based on the available phase diagram data as well as thermodynamic property data. The Fcc phase is modeled as (Hf, Va)1(N, Va)1 to cover the composition range since the solubility of nitrogen in Fcc phase is reported up to about 52 at.%. A set of self-consistent thermodynamic parameters for the Hf-N system has been obtained. The computed phase diagrams and thermodynamic quantities using the present parameters agree well with the experimental data.

scholarly journals Thermodynamic modeling of the Al-K system

2009 ◽  
Vol 45 (1) ◽  
pp. 89-93 ◽  
Author(s):  
Y. Du ◽  
X. Yuan ◽  
W. Sun ◽  
B. Hu
Keyword(s):  
Phase Diagram ◽  
Gas Phase ◽  
Thermodynamic Modeling ◽  
Phase Diagram Data ◽  
Ideal Gas ◽  
Monotectic Reaction ◽  
Present Calculation ◽  
Experimental Phase ◽  
Experimental Phase Diagram ◽  
Ideal Gas Model

A thermodynamic modeling for the Al-K system is conducted. The thermodynamic parameters for liquid, (Al), and (K) are evaluated by using the experimental phase diagram data from the literature. The gas phase is described with an ideal gas model. The calculated Al-K phase diagram agrees well with the experimental data. In particular, the observed monotectic reaction is well described by the present calculation.

scholarly journals Thermodynamic description of the C-Ge and C-Mg systems

2010 ◽  
Vol 46 (1) ◽  
pp. 97-103 ◽  
Author(s):  
B. Hu ◽  
Y. Du ◽  
H. Xu ◽  
W. Sun ◽  
W.W. Zhang ◽  
...  
Keyword(s):  
Thermodynamic Parameters ◽  
Enthalpy Of Formation ◽  
Thermodynamic Modeling ◽  
First Principles ◽  
Thermodynamic Description ◽  
Calphad Method ◽  
Thermodynamic Calculations ◽  
First Principles Calculation ◽  
System A ◽  
The Enthalpy Of Formation

The thermodynamic modeling for the C-Ge and C-Mg systems is performed by the CALPHAD method. The enthalpy of formation for Mg2C3, the experimental value of which is not available in the literature, is obtained via first-principles calculation to refine the thermodynamic modeling of the C-Mg system. A comparison of the thermodynamic calculations with the available literature data shows that the presently obtained two sets of thermodynamic parameters for the C-Ge and C-Mg systems can well describe the these two systems.

Static dielectric pretransitional effects in thermotropic liquid crystals

2008 ◽  
Vol 16 (4) ◽  
Author(s):  
J. Jadżyn ◽  
G. Czechowski
Keyword(s):  
Liquid Crystalline ◽  
Helmholtz Free Energy ◽  
Electronic Devices ◽  
Thermodynamic Quantities ◽  
Static Permittivity ◽  
Temperature Behaviour ◽  
Isotropic Liquid ◽  
First Order ◽  
Thermotropic Liquid Crystals ◽  
First Order Transition

AbstractThe paper presents a review of recent results on static dielectric behaviour in vicinity of weakly first order transition from isotropic liquid to a liquid crystalline nematic phase of compounds used in opto-electronic devices. Temperature behaviour of static permittivity and its derivative are interpreted in terms of a basic thermodynamic quantities increment (internal energy, entropy and Helmholtz free energy) induced by a probing electric field.

scholarly journals Thermodynamic description of metastable fcc/liquid phase equilibria and solidification kinetics in Al-Cu alloys

2022 ◽  
Vol 380 (2217) ◽  
Author(s):  
Yindong Fang ◽  
Peter K. Galenko ◽  
Dongmei Liu ◽  
Klaus Hack ◽  
Markus Rettenmayr ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Phase Equilibria ◽  
High Speed ◽  
Thermodynamic Description ◽  
General Nature ◽  
Miscibility Gap ◽  
Velocity Versus ◽  
Sharp Interface Model ◽  
Cu Alloys ◽  
Fcc Phase

The thermodynamic description of the fcc phase in the Al-Cu system has been revised, allowing for the prediction of metastable fcc/liquid phase equilibria to undercoolings of Δ T  = 421 K below the eutectic temperature. Hypoeutectic Al-Cu alloys that are prone to pronounced microsegregation were solidified containerlessly in electromagnetic levitation. Solidus and liquidus concentrations were experimentally determined from highly undercooled samples employing energy-dispersive X-ray analysis. Solid concentrations at a rapidly propagating solid/liquid interface were additionally calculated using a sharp interface model that considers all undercoolings and is based on solvability theory. Modelling results (front velocity versus undercooling) were also corroborated by in situ observation with a high-speed camera. A newly established thermodynamic description of the fcc phase in Al-Cu is compatible with existing CALPHAD-type databases. Inconsistencies of previous descriptions such as a miscibility gap between Al-fcc and Cu-fcc on the Al-rich side, an unrealistic curvature of the solidus line in the same composition range or an azeotropic point near the melting point of Cu, are amended in the new description. The procedure to establish the description of phase equilibria at high undercoolings can be transferred to other alloy systems and is of a general nature. This article is part of the theme issue 'Transport phenomena in complex systems (part 2)'.

scholarly journals THERMODYNAMIC MODELING OF OXIDE MELTS OF CaO - Al2O3 - SiO2 SYSTEMS

2019 ◽  
Vol 63 (1) ◽  
pp. 45-50
Author(s):  
Svetlana E. Pratskova ◽  
Vladimir A. Burmistrov ◽  
Anna A. Starikova
Keyword(s):  
Phase Diagrams ◽  
Thermodynamic Modeling ◽  
Binary Systems ◽  
Thermodynamic Description ◽  
Ternary Systems ◽  
Oxide Melt ◽  
State Diagrams ◽  
Gibbs Energies ◽  
Metallurgical Slags ◽  
Oxide Melts

Oxide melts of the CaO – Al2O3 – SiO2 system are the basis of metallurgical slags. Therefore, the thermodynamic properties of this system have been repeatedly studied experimentally, and attempts have been made to describe them theoretically. Thermodynamic modeling of the state diagrams of the CaO – Al2O3, CaO – SiO2, Al2O3 – SiO2 binary systems, as well as the CaO – Al2O3 – SiO2 ternary system was performed. In the course of the work, expressions for the thermodynamic description of the activities of the components of the oxide melt of this system are derived. For the calculation, a generalized theory of regular ionic solutions was used. The energy parameters of the theory are determined, depending on the temperature and composition of the solution, using experimental data on the heat and melting point of oxides of calcium, aluminum and silicon. According to the results of the simulation, the coordinates of the points of nonvariant transformations in the phase diagrams of the binary and ternary systems under study are determined. The obtained results on thermodynamic modeling of the coordinates of the liquidus lines of the phase diagrams of the CaO – Al2O3, CaO – SiO2, Al2O3 – SiO2 binary systems were compared with the literature data for the studied systems. The calculated diagrams are in good agreement with the experimental ones, which indicates the applicability of the chosen system for the description of such oxide melts. The modeling technique used in this work allowed to estimate the Gibbs energies of formation of silicates and calcium aluminum silicates to be 3Al2O3∙2SiO2, 3CaO∙SiO2, 2CaO∙SiO2, 3CaO∙2SiO2, CaO∙SiO2, CaO∙Al2O3∙2SiO2, 2CaO∙Al2O3∙SiO2 on the base of obtained aquations for of activities of the components and calculated parameters of the theory. The calculated diagrams will allow to determine the nature of the interaction between the components of the system, the conditions of formation, the composition and properties of the compounds formed, without isolating them from the system.

Studies on Phenylpyruvic Acid, II. Keto-Enol Equilibrium in Water-Dimethylsulphoxide Mixtures

1976 ◽  
Vol 31 (11-12) ◽  
pp. 641-645 ◽  
Author(s):  
L Cassidei ◽  
A Dell 'atti ◽  
O. Sciacovelli
Keyword(s):  
Hydrogen Bonding ◽  
Spectroscopic Study ◽  
Composition Range ◽  
Optimum Composition ◽  
Analytical Determination ◽  
Thermodynamic Quantities ◽  
Phenylpyruvic Acid ◽  
Experimental Conditions ◽  
Temperature Range ◽  
Pure Dmso

Abstract A spectroscopic study of the keto-enol equilibrium of phenylpyruvic acid (PPA) was performed in water-dimethylsulphoxide (DMSO) mixtures, throughout the composition range and in an ex­ tended temperature range. The thermodynamic quantities of the tautomerism were also calculated. The high value of enolization entropy in pure DMSO is attributed to hydrogen bonding of PPA to this solvent. The experimental conditions and the optimum composition range of the H2O-DMSO mixtures for PPA analytical determination were determined.

scholarly journals Bandgap and refractive index estimates of InAlN and related nitrides across their full composition ranges

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Shahab N. Alam ◽  
Vitaly Z. Zubialevich ◽  
Bijan Ghafary ◽  
Peter J. Parbrook
Keyword(s):  
Refractive Index ◽  
Alloy Composition ◽  
Composition Range ◽  
Electronic Devices ◽  
Ternary Alloys ◽  
Refractive Index Dispersion ◽  
Direct Relevance ◽  
Index Data ◽  
Dispersion Data ◽  
Refractive Index Data

Abstract III-Nitride bandgap and refractive index data are of direct relevance for the design of (In, Ga, Al)N-based photonic and electronic devices. The bandgaps and bandgap bowing parameters of III-nitrides across the full composition range are reviewed with a special emphasis on InxAl1−xN, where less consensus was reached in the literature previously. Considering the available InAlN data, including those recently reported for low indium contents, empirical formulae for InAlN bandgap and bandgap bowing parameter are proposed. Applying the generalised bandgap data, the refractive index dispersion data available in the literature for III-N alloys is fitted using the Adachi model. For this purpose, a formalism involving a parabolic dependence of the Adachi parameters on the dimensionless bandgap $${\xi }_{{E}_{\mathrm{g}}}=\left({E}_{\mathrm{g}, {\mathrm{A}}_{x}{\mathrm{B}}_{1-x}\mathrm{N}}-{E}_{\mathrm{g},\mathrm{ BN}}\right)/\left({E}_{\mathrm{g}, \mathrm{AN}}-{E}_{\mathrm{g},\mathrm{ BN}}\right)$$ ξ E g = E g , A x B 1 - x N - E g , BN / E g , AN - E g , BN of the corresponding ternary alloys is used rather than one directly invoking the alloy composition.

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