scholarly journals Carbides and Nitrides of Zirconium and Hafnium

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2728 ◽  
Author(s):  
Sergey V. Ushakov ◽  
Alexandra Navrotsky ◽  
Qi-Jun Hong ◽  
Axel van de Walle
Keyword(s):  
Experimental Data ◽  
Phase Equilibria ◽  
Ab Initio ◽  
Solid Solutions ◽  
Binary Systems ◽  
Experimental Studies ◽  
Published Data ◽  
Oxygen Solubility ◽  
Melting Temperatures ◽  
Ab Initio Computations

Among transition metal carbides and nitrides, zirconium, and hafnium compounds are the most stable and have the highest melting temperatures. Here we review published data on phases and phase equilibria in Hf-Zr-C-N-O system, from experiment and ab initio computations with focus on rocksalt Zr and Hf carbides and nitrides, their solid solutions and oxygen solubility limits. The systematic experimental studies on phase equilibria and thermodynamics were performed mainly 40–60 years ago, mostly for binary systems of Zr and Hf with C and N. Since then, synthesis of several oxynitrides was reported in the fluorite-derivative type of structures, of orthorhombic and cubic higher nitrides Zr3N4 and Hf3N4. An ever-increasing stream of data is provided by ab initio computations, and one of the testable predictions is that the rocksalt HfC0.75N0.22 phase would have the highest known melting temperature. Experimental data on melting temperatures of hafnium carbonitrides are absent, but minimum in heat capacity and maximum in hardness were reported for Hf(C,N) solid solutions. New methods, such as electrical pulse heating and laser melting, can fill the gaps in experimental data and validate ab initio predictions.

Concentration Dependence of the Surface Tension of Three and Four-Component Systems with Peculiarities in the Surface Tension Isotherms of Lateral Binary Melts

2021 ◽  
Vol 1022 ◽  
pp. 194-202
Author(s):  
R.Kh. Dadashev ◽  
R.A. Kutuev
Keyword(s):  
Experimental Data ◽  
Surface Tension ◽  
Concentration Dependence ◽  
Experimental Error ◽  
Binary Systems ◽  
Experimental Studies ◽  
Study Results ◽  
Component Systems ◽  
Minimum Depth ◽  
Surface Tension Isotherms

The experimental study results of the melts concentration dependence of the surface tension of the four-component indium-tin-lead-bismuth system and its constituent binary systems of indium-tin, indium-lead, indium-bismuth, tin-lead, tin-bismuth, lead-bismuth are presented in the paper. It is shown that the concentration dependence of the melts surface tension of the In-Sn-Pb-Bi four-component system can be predicted from the data on ST (surface tension) values of lateral binary systems. Features in the ST isotherms in the form of a minimum are observed only in the indium-tin lateral system from all lateral binaries. A distinctive feature of the detected minimum is that the minimum depth slightly exceeds the experimental error. Therefore, in addition to the fact that the area of average compositions was studied more thoroughly, we carried out the surface tension measurements by two independent methods. The experimental data obtained by both methods coincide within the experimental error and indicate the extremum availability on ST isotherms. Thus, ST experimental studies by two independent methods confirmed the presence of a flat minimum on ST isotherms of the indium-tin binary system increasing the reliability of the obtained data. The obtained outcomes and their comparison with experimental data have shown that the considered models for predicting surface properties based on data due to similar properties of lateral binary systems adequately reflect the experimental dependences. However, the prediction model based on Kohler's method of excess values describes the experimental curves more accurately.

Thermodynamic Calculation of the Heavy Rare Earth Permanent Magnets: Fe-RE (RE=Gd, Tb, Dy, Lu) Binary Systems

2017 ◽  
Vol 1142 ◽  
pp. 62-68
Author(s):  
Xiao Long Chen ◽  
Jiang Wang ◽  
Tai Li Chen ◽  
Mao Hua Rong ◽  
Guang Hui Rao ◽  
...  
Keyword(s):  
Experimental Data ◽  
Magnetic Properties ◽  
Phase Equilibria ◽  
Binary Systems ◽  
Permanent Magnets ◽  
Ternary Systems ◽  
Calphad Method ◽  
Experimental Investigations ◽  
Heavy Rare Earth ◽  
Microstructure And Magnetic Properties

The Fe-RE (RE=Gd, Tb, Dy, Lu) binary systems with the experimental data of phase equilibria and thermodynamic properties in the published literature were reviewed firstly. Based on available phase equilibria data and thermodynamic data, the Fe-RE (RE=Gd, Tb, Dy, Lu) binary systems were assessed thermodynamically using the CALPHAD method. As a result, further experimental investigations and thermodynamic calculations would be both required in order to develop thermodynamic database of the RE-Fe-B ternary systems, which is very useful to study the relations between alloy compositions, microstructure and magnetic properties of novel Nd-Fe-B-based permanent magnets.

Alloys Based on Crystallochemical and Geometric Parameters of Palladium Crystal Structure

2014 ◽  
Vol 1013 ◽  
pp. 41-48 ◽  
Author(s):  
Мaksim Morozov ◽  
Aleksandr I. Potekaev ◽  
Anatolii A. Klopotov ◽  
Valentina Kulagina ◽  
Тatyana Markova ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Equilibria ◽  
Solid Solutions ◽  
Binary Systems ◽  
Structural Phase ◽  
Hydrogen Permeability ◽  
Crystal Chemical ◽  
Packing Factor ◽  
Geometric Factors ◽  
Ordered Phases

The results of the analysis of phase equilibria ordered phases in binary systems based on palladium Pd-Me (Me = Co, Rh, Ir, Cu, Ag, Au, Ni, Pt) are set out to search for correlations and crystal-chemical and crystal geometric factors. It is found that the packing factor in disordered solid solutions in binary systems based on Pd is close to the value of 0.74 on a background of a slight deviation from the atomic volumes Xena. It is revealed that increasing of the hydrogen permeability in Cu-Pd binary alloys correlates with significant reduction of the packing factor in B2 ordered phase in the range of 40 at.% Pd. It is found that various structural-phase states are formed in Pd-Me binary systems with certain combinations of temperature and size factors.

scholarly journals Phase complex model of ternary reciprocal system Na+,Sr2+||WO42-,MoO42-

2019 ◽  
Vol 59 (8) ◽  
pp. 103-115
Author(s):  
Alexander V. Burchakov ◽  
Keyword(s):  
Phase Equilibria ◽  
Solid Solutions ◽  
Binary Systems ◽  
Reciprocal System ◽  
Condensed State ◽  
Continuous Series ◽  
Algebraic Equations ◽  
Reaction Products ◽  
System Components ◽  
Phase Complex

The paper presents the results of a theoretical study of the phase complex of a three-component reciprocal system consisting of sodium and strontium tungstates and molybdates. Previously, a literature review was conducted on data on phase equilibria in the condensed state of individual salts, binary faceting systems. In two Na2MoO4 – SrMoO4 and Na2WO4 – SrWO4 binary systems, a eutetic equilibrium is observed with the formation of solid phases corresponding to the system components, and in two other Na2MoO4 – Na2WO4 and SrMoO4 – SrWO4 binary systems, one phase of a continuous series of solid solutions crystallizes. Based on the mathematical model of the molar balance, one can uniquely determine the quantities of reaction products, the molecular formulas of solid solutions, and the equations of chemical reactions for an arbitrary mixture of system components. This model represents a set of algebraic equations by which the balance is calculated. To build a 3D computer model, the paper presents the equations for the conversion of coordinates from barycentric to Cartesian. The model is implemented in concentration-temperature coordinates using the KOMPAS-3D program using experimental data on the system. The model is built in two interpretations: based on data on the faceting elements and on the basis of all available data about the system. Comparison of the two models makes it possible to evaluate the predictive ability carried out using 3D modeling. From this comparison, it was found that using the 3D model it is possible to conduct a preliminary a priori forecast of phase equilibria in order to identify the structure of phase diagrams at the qualitative and quantitative levels. The projection of the crystallization polytherm onto the square of the compositions is represented by two fields of solid solutions – Na2MoxW1-xO4 and SrMoxW1-xO4. Isothermal and polythermal sections were constructed. The system implements di- and monovariant equilibria.

Experimental Study and Thermodynamic Modeling of Phase Equilibria in BaO-Fe2O3 System

2016 ◽  
Vol 843 ◽  
pp. 16-21 ◽  
Author(s):  
D.A. Vinnik ◽  
E.A. Trofimov ◽  
D.A. Zherebtsov
Keyword(s):  
Phase Diagram ◽  
Experimental Study ◽  
Phase Equilibria ◽  
Thermodynamic Modeling ◽  
Published Data ◽  
Melting Temperatures

This paper presents the results of the synthesis of compounds of BaO-Fe2O3 system and the results of the study of nature and the melting temperatures of the resulting compounds. Based on the analysis of published data, as well as the results of our studies the systematization of information on the BaO-Fe2O3 system was conducted and an updated phase diagram of this system was proposed.

scholarly journals Linking ab initio Energetics to Experiment: Kinetic Monte Carlo Simulation of Transient Enhanced Diffusion of B in Si

1998 ◽  
Vol 538 ◽  
Author(s):  
Silva K. Theiss ◽  
M.-J. Caturla ◽  
T. Diaz de la Rubia ◽  
M.C. Johnson ◽  
Ant Uralt ◽  
...  
Keyword(s):  
Experimental Data ◽  
Monte Carlo ◽  
Ab Initio ◽  
Time Scales ◽  
First Principles ◽  
Kinetic Monte Carlo ◽  
Experimental Studies ◽  
Enhanced Diffusion ◽  
Transient Enhanced Diffusion ◽  
Wide Range

AbstractWe have developed a kinetic Monte Carlo (kMC) simulator that links atomic migration and binding energies determined primarily from first principles calculations to macroscopic phenomena and laboratory time scales. Input for the kMC simulation is obtained from a combination of ab initio planewave pseudopotential calculations, molecular dynamics simulations, and experimental data. The simulator is validated against an extensive series of experimental studies of the diffusion of B spikes in self-implanted Si. The implant energy, dose, and dose rate, as well as the detailed thermal history of the sample, are included. Good agreement is obtained with the experimental data for temperatures between 750 and 950°C and times from 15 to 255 s. At 1050°C we predict too little diffusion after 105 s compared to experiment: apparently, some mechanism which is not adequately represented by our model becomes important at this temperature. Below 1050°C, the kMC simulation produces a complete description over macroscopic time scales of the atomic level diffusion and defect reaction phenomena that operate during the anneals. This simulator provides a practical method for predicting technologically interesting phenomena, such as transient enhanced diffusion of B, over a wide range of conditions, using energetics determined from first-principles approaches.

scholarly journals Experimental Data of Fluid Phase Equilibria- Correlation and Prediction Models: A Review

Processes ◽  
2019 ◽  
Vol 7 (5) ◽  
pp. 277 ◽  
Author(s):  
Urszula Domańska
Keyword(s):  
Phase Equilibria ◽  
Binary Systems ◽  
Prediction Models ◽  
Research Work ◽  
Ternary Mixtures ◽  
Excess Gibbs Free Energy ◽  
Future Research ◽  
Published Data ◽  
Gas Liquid Chromatography ◽  
Excess Molar Enthalpy

The examples of phase equilibria in binary systems, solid/liquid (SLE), liquid/liquid (LLE), vapor/liquid (VLE), as well as liquid/liquid equilibria in ternary systems mainly containing ionic liquids (ILs), or the infragrance materials, or pharmaceuticals with molecular organic solvents, such as an alcohol, or water, or hydrocarbons, are presented. The most popular correlation methods of the experimental phase equilibrium data are presented, related to the excess Gibbs free energy models such as Wilson, universal-quasichemical, UNIQUAC and non-random two-liquid model, NRTL as well as several popular theories for the modeling of the phase equilibria and excess molar enthalpy, HE in binary or ternary mixtures are presented: the group contribution method (Mod. UNIFAC) and modified UNIFAC model for pharmaceuticals and lattice theory based on non-random hydrogen bonding (NRHB). The SLE, LLE, or VLE and HE of these systems may be described by the Perturbed-Chain Polar Statistical Associating Fluid Theory (PC-SAFT), or a Conductor-like Screening Model for Real Solvents (COSMO-RS). The examples of the application of ILs as extractants for the separation of aromatic hydrocarbons from alkanes, sulfur compounds from alkanes, alkenes from alkanes, ethylbenzene from styrene, butan-1-ol from water phase, or 2-phenylethanol (PEA) from water are discussed on the basis of previously published data. The first information about the selectivity of extrahent for separation can be obtained from the measurements of the limiting activity coefficient measurements by the gas–liquid chromatography technique. This review outlines the main research work carried out over the last few years on direct measurements of phase equilibria, or HE and limiting activity coefficients, the possibility of thermodynamic modeling with emphasis on recent research achievements and potential for future research.

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