Ternary Melts Research Articles

Partial and integral enthalpies of mixing of Cu-Fe-Ti melts at 1873 K

The partial enthalpy of mixing of titanium in Cu-Fe-Ti melts are studied by high-temperature isoperibolic calorimetry at 1873 K in the composition range xTi = 0–0.6 along three sections with a ratio xFe / xCu = 1/3, 1, and 3. The integral enthalpy of mixing of the ternary melts is calculated by integrating the Gibbs-Duhem equation and is described in terms of the Redlich-Kister-Muggianu model. Function ΔH demonstrates negative values over a wide concentration range. The contribution of a ternary interaction to the enthalpy of mixing of Cu-Fe-Ti melts is mainly positive. The first partial enthalpies of mixing of Al, Sn, Si, Y, Zr, Hf, and Ni with Cu-Fe-Ti melts are negative and indicate an increase of the thermodynamic stability of the liquid phase upon the dissolution of these additions.

Solidification of a ternary melt from a cooled boundary, or nonlinear dynamics of mushy layers

We present a mathematical model and its analytical solution describing directional solidification of a ternary (three-component) system cooled from below. We focus on the solidification theory in the presence of two distinct mushy layers: (1) solidification along a liquidus surface is characterized by a primary mushy layer, and (2) solidification along a cotectic line is characterized by a secondary (cotectic) mushy layer. We consider the case when the phase transition temperatures in two mushy layers represent arbitrary functions of the compositions. We obtain an exact analytical solution of the nonlinear set of equations and boundary conditions in the case of a self-similar solidification scenario. Model predictions are in good agreement with existing experimental data.

Interplay between microscopic and macroscopic phase separations in ternary polymer melts: Insight from mesoscale modelling

We present a mesoscale computational study of a ternary polymer melt comprising of two immiscible homopolymers A and B, and a symmetric diblock copolymer AB. The system exhibits rich phase behavior such as microphase separations in the copolymer-rich region and macrophase separations in the homopolymer-rich region. We use Dissipative Particle Dynamics (DPD) and Dynamic mean-field Density Functional Theory (DDFT) to predict the phase behavior along a temperature–homopolymer volume fraction isopleth for an A/B/AB mesoscale system that mimics a real system of low molecular weight poly(dimethyl siloxane) (PDMS) and poly(ethyl ethylene) (PEE) homopolymers, and a nearly symmetric PDMS–PEE diblock copolymer. The mesoscale polymer parameters are derived using a top-down coarse-graining approach that utilizes order–disorder and critical temperatures. Boundaries between disordered, lamellar and two-phase regions of the phase diagram are determined by visual inspection of configurational snapshots in combination with the abrupt changes that are exhibited by the diblock-copolymer orientational order parameter and bead order parameter when the phase boundaries are crossed. Phase diagrams predicted by DPD and DDFT agree reasonably well with the experimental phase diagram of the PDMS/PEE/PDMS–PEE system except for a narrow channel of bicontinuous microemulsion that is not predicted by either the DPD or the DDFT models. We discuss possible refinements of the models to capture this bicontinuous phase.

Amide-based Room Temperature Molten Salt as Solvent cum Stabilizer for Metallic Nanochains

A simple and efficient method for spontaneous organization of long assemblies of gold nanoparticles is described. This is achieved in a molten solvent containing acetamide, urea and ammonium nitrate that acts as a solvent cum stabilizer. There is no external aggregating agent or stabilizing agent added to the system. Depending on the concentration of the metal salt in the ternary melt, either chain-like assemblies or individual nanoparticles could be obtained. The amine groups present in the components of the melt (acetamide and urea) help in the stabilization of nanoparticles. Ammonium ions present in the eutectic mixture are likely to assist in the organization of the particles. The method is simple, highly reproducible and does not require any templating agent for the formation of chain-like assemblies.

Growth of High-Quality Decagonal Al–Cu–Co Quasicrystals from Ternary Melt

By changing the initial elements, we obtain high-quality samples of Al–Cu–Co decagonal quasicrystals with a wide range of composition. The sizes of the samples are typically several centimetres in length and 2–3 mm in diameter. These samples are identified to be decagonal single grains by powder x-ray diffraction method, and the composition is homogeneous confirmed by EDX and chemical method.

A high performance composite ionic conducting electrolyte for intermediate temperature fuel cell and evidence for ternary ionic conduction

The performance of a composite electrolyte composed of a samarium doped ceria (SDC) and a ternary eutectic carbonate melt phase was examined. The formation temperature of a continuous carbonate melt phase is crucial to the high conductivity of this material. The electrolyte contains 30 and 50 wt% carbonate exhibited a sharp increase of conductivity at a temperature close to the melting point of the eutectic carbonate, ca 400 °C, which is more than 100 °C lower than those electrolytes using binary carbonate. At around 650 °C, and with CO 2/O 2 used as the cathode gas, the fuel cell gave a power output 720 mW cm −2 at a current density 1300 mA cm −2. Water was measured in both the anode and cathode outlet gases and CO 2 was detected in the anode outlet gas. When discharged at 800 mA cm −2, a stable discharge plateau was obtained. The CO 2 in the cathode gas enhances the power output and the stability of the single cell. Based on these experimental facts, a ternary ionic conducting scheme is proposed and discussed.

Growth of 2H-SiC Single Crystals in a C-Li-Si Ternary Melt System

We have achieved the first successful growth of 2H-SiC single crystals using the C-Li-Si melt system. Li-Si melt, whose melting point is lower than 1000 oC, was chosen because the 2H-SiC polytype is more stable at lower temperatures than other polytypes such as 3C-, 4H-, and 6H-SiC. Many hexagonal-shaped crystals of approximately 100 m in diameter were observed via a scanning electron microscope (SEM). A high resolution transmission electron microscope (HR-TEM) lattice image of the grown crystals showed a periodical structure with A-B stacking along the <0001> direction. These results indicated that the Li-based flux was useful for growing bulk 2H-SiC single crystals.

The influence of Si,B substitution and of the nature of network-modifying cations on the properties and structure of borosilicate glasses and melts

The influence of the Si,B substitution and of the nature of network-modifying cations on viscosities and heat capacities of ternary borosilicate melts has been investigated for two series of melts containing either 20 mol% Na 2O or 33 mol% BaO. The measurements have been made near the glass transition and above the liquidus for viscosities, and from 300 to 1073 K for heat capacities. They have been used to determine the configurational entropies of the melts from Adam and Gibbs theory of relaxation processes. To complete these observations, the room-temperature Raman spectra of the glasses have also been recorded. The observed increase in the configurational heat capacity of melts with B 2O 3 content indicates the existence of strong temperature-induced structural changes induced by the presence of boron. Correlatively, the viscosity variations with composition can be related to the existence of distinct coordination environments for boron. As for the effects of barium and sodium, they are similar in silicate and borosilicate melts, and depend mainly on the field strength of the cation.

High-performance dye-sensitized solar cells based on solvent-free electrolytes produced from eutectic melts

Low-cost excitonic solar cells based on organic optoelectronic materials are receiving an ever-increasing amount of attention as potential alternatives to traditional inorganic photovoltaic devices. In this rapidly developing field, the dye-sensitized solar cell (DSC) has achieved so far the highest validated efficiency of 11.1% (ref. 2) and remarkable stability. However, the cells with the best performance use volatile solvents in their electrolytes, which may be prohibitive for outdoor solar panels in view of the need for robust encapsulation. Solvent-free room-temperature ionic liquids have been pursued as an attractive solution to this dilemma, and device efficiencies of over 7% were achieved by using some low-viscosity formulations containing 1-ethyl-3-methylimidazolium thiocyanate, selenocyanate, tricyanomethide or tetracyanoborate. Unfortunately, apart from tetracyanoborate, all of these low-viscosity melts proved to be unstable under prolonged thermal stress and light soaking. Here, we introduce the concept of using eutectic melts to produce solvent-free liquid redox electrolytes. Using a ternary melt in conjunction with a nanocrystalline titania film and the amphiphilic heteroleptic ruthenium complex Z907Na (ref. 10) as a sensitizer, we reach excellent stability and an unprecedented efficiency of 8.2% under air-mass 1.5 global illumination. Our results are of importance to realize large-scale outdoor applications of mesoscopic DSCs.

Experimental investigation and joint description of the thermodynamic properties of Ni-Cr-Al melts

Original high-temperature isoperibolic calorimeter was used to study experimentally concentration dependences of the partial and integral enthalpies of mixing of Ni-Cr-Al melts. Pseudo-binary sections corresponding to the ratios (8 Ni/2 Cr) and (9 Ni/1 Cr) of the ternary Ni-Cr-Al system were experimentally investigated at 1823K. The partial and integral enthalpies of mixing of chromium, nickel and aluminium as a function of the atomic fraction of aluminium have been measured. A self-consistent computer description of the thermodynamic properties of the components in the wide concentration and temperature intervals have been obtained using physical-chemical models. The description of the ternary melts Ni-Al-Cr is based on the boundary Ni-Cr, Ni-Al and Al-Cr melts and fits well the experimental data.

Polyassociative model of A 2B 6 semiconductor melt and p− T− x equilibria in Cd–Hg–Te system

According to the assumption based on the existence of the set of different composition complexes in the liquid phase (polyassociative model), compositions and parameters of the associates formation in Cd–Hg–Te system were found. It is shown that the mixing effects in the binary melts Cd–Te and Hg–Te are described making use of ATe, A 2Te, ATe 2 and A 2Te 3 associates (A=Cd, Hg). Besides that, in Cd–Hg–Te ternary melt the mixing effect between the metallic components are described by CdHgTe and CdHgTe 3 associates. The obtained dissociation parameters of these complexes and also the parameters of the complexes formation in the initial binary systems enabled to describe p− T− x equilibria in the ternary system in the wide temperature range. The results are compared with the experimental data.

CrossRef Listing of Deleted DOIs

The associated solution model recently applied to four binary metal-sulfur melts, Fe-S, Ni-S, Co-S, and Cu-S, is extended to ternary metal-sulfur melts from those of the binary melts. The proposed equations are used to predict the thermodynamic properties of Cu-Ni-S melts. The predicted values for the activity of sulfur at 1,473 and 1,673 K are in good agreement with the experimental data. Using these data and other pertinent thermodynamic data, two isothermal sections at 1,473 and 1,673 K are calculated. The calculated isothermal sections agree well with the experimental data available in the system.

A comparison of traditional geometrical models and mass triangle model in calculating the surface tensions of ternary sulphide melts

Surface tension of the Ni 3S 2–FeS–Cu 2S ternary mattes has been calculated using a mass triangle model as well as six traditional geometrical models based on the same calculation data to investigate the difference between mass triangle model and other kinds of geometrical models. From the calculated results, it might be seen that, the mass triangle model, irrespective of the method of selection of the binary data, would give the best results compared with other traditional geometrical models. The mean square root errors of the mass triangle method only range from 1.09% to 2.8%, which are almost within the experimental error of 2.5%.

Thermodynamic properties and structure of ternary silicate glass-forming melts: Experimental studies and modeling

Abstract Thermodynamic properties and vaporization processes of ternary silicate glass-forming melts containing Cs2O, MgO, CaO, BaO, B2O3, Al2O3 and TiO2 obtained by high temperature mass spectrometric method at the temperatures up to 1900 K were discussed. These data were used for modeling thermodynamic properties and structure of these melts based on the vacancy model of the general lattice theory of associated solutions.

The thermodynamic characteristics of formation of alloys in the Ge-Ga-Mn and Si-Ni-Al systems

The enthalpies of mixing of ternary system melts were determined by high-temperature calorimetry under isoperibolic conditions. For the Ge-Ga-Mn system, measurements were taken at 1780 ± 5 K along five ray sections with constant ratios between the atomic fractions of germanium and gallium up to a ∼0.6 mole fraction of manganese; the xGe/xGa ratios were 0.8/0.2, 0.7/0.3, 0.5/0.5, 0.3/0.7, and 0.15/0.85. For the Si-Ni-Al system, measurements were taken at 1770 ± 5 K along five ray sections with constant ratios between the atomic fractions of silicon and nickel up to a ∼0.6 mole fraction of aluminum; the xSi/xNi fratios were 0.85/0.15, 0.7/0.3, 0.5/0.5, 0.3/0.7, and 0.15/0.85. The formation of melts in these systems was found to be exothermic over the composition range studied. The integral enthalpies of melt formation were maximum along the xGe/xGa = 0.8/0.2 section in the Ge-Ga-Mn system (−18.8 ± 3.3 kJ/mol) and along the xSi/xNi = 0.5/0.5 section in the Si-Ni-Al system (−67.8 ± 3.4 kJ/mol). An analysis of the isolines of the integral enthalpies of mixing led us to conclude that the Ge-Mn and Ga-Mn binary systems had the strongest influence on the thermodynamic characteristics of melt formation in the Ge-Ga-Mn system, the predominant influence being that of the Ge-Mn binary system. An analysis of the energy characteristics of melt formation in the Si-Ni-Al ternary system showed that the major contribution was made by the interaction of components in the Si-Ni and Ni-Al boundary binary systems, the influence of the Si-Ni system being stronger.

Growth of 2H–SiC single crystals in a Li-based flux

Growth of bulk 2H–SiC single crystals in a C–Li–Si ternary melt system was successful. The growth of 2H–SiC must be conducted at lower temperatures than that of other SiC poly-types. The lithium flux solved this problem, as it is usable for growth under 1000 °C due to its low melting temperature. Success in the growth of 2H–SiC single crystals in this study may unlock the potential for realizing high-performance electronic devices by fabricating the devices on 2H–SiC single-crystal substrates.

Energy model for the Zr-based metallic glass alloy melt with clusters

An energy model for the melt of bulk metallic glass (BMG) with clusters was established, the Gibbs free energy and interfacial energy for the Zr-Al-Ni ternary alloy melt with Zr2Ni clusters were calculated, and the effects of the clusters on the Gibbs free energy, interfacial energy and nucleation rate were analyzed. The results showed that the existence of the clusters in the Zr-Al-Ni ternary alloy melt enables the Gibbs free energy to decrease in the composition range where bulk metallic glass forms easily, makes the interfacial energy increase and changes the distribution of the interfacial energy with the alloy composition. Because of the clusters in the melt, the Gibbs free energy of the Zr66Al8Ni26 alloy melt decreases about 0.3–1 kJ/mol and the interfacial energy between the melt and crystal nucleus increases about 0.016 J/m2. The nucleation rate of the undercooled Zr66Al8Ni26 alloy melt decreases evidently under the influence of the clusters on Gibbs free energy and the interfacial energy, and the maximum of the nucleation rate in the melt with the Zr2Ni clusters is only about 107 mol−1·s−1.

Compositional controls on melting and dissolving a salt into a ternary melt

We explore theoretically the controls on dissolution of salt A, in an undersaturated brine of salts A and B. We show that, as the concentration of B increases, the dissolution rate of A decreases, for brine of given temperature. We also show that there is a sharper decrease in dissolution rate with increasing concentration, for concentrations of B above a critical value, where B limits the equilibrium concentration. We explore the implications of the predictions for dissolution of KCl or NaCl, by a mixed brine of NaCl and KCl, a common reaction that may arise in dissolution of evaporites. We predict that, with mixed-composition brine, KCl crystals dissolve more rapidly than NaCl crystals, unless the (far-field) brine is nearly saturated in KCl. We also predict that the dissolution rate of these salts is largely independent of fluid temperature and is controlled by compositional diffusion.

Enthalpy of mixing of liquid Cu-Ti-Zr alloys

The enthalpy of mixing of liquid Cu-Ti-Zr ternary alloys is studied by high-temperature isoperibolic calorimetry at 1873 K along three ray sections characterized by the ratios xZr: xCu = 3: 7, xTi: xCu = 3: 7, and xZr: xTi = 1 at xCu = 1−0.4. The isotherm of the integral enthalpy of mixing of these melts is described in terms of the Redlich-Kister-Muggianu model. Along with the substantial contributions of binary copper-titanium and copper-zirconium interactions, the contribution of a ternary interaction to the enthalpy of mixing of liquid Cu-Ti-Zr alloys also exists. The first partial enthalpies of mixing of Ni, Al, Si, Sn, and Y with the melts are studied to determine the character of the interaction between the ternary Cu-Ti-Zr melts and metal additions that facilitate amorphization upon melt quenching. The introduction of these metals into the ternary melts is shown to increase their thermodynamic stability.

An Approach to Modeling Al2O3 Containing Slags with the Cell Model

The cell model originally developed by Kapoor and Frohberg for binary and ternary silicate melts was later extended to multi-component liquid slags by Gaye and Welfringer. CSIRO has extended the application of this model to describe the behaviour of a large number of oxide species commonly found in metallurgical slags. One limitation of the model was that when using only binary parameters to model ternary or higher order systems, the thermodynamic behaviour of the components in Al2O3 containing systems cannot be represented accurately. Based on an analysis of the structural role played by oxide components in the CaO-Al2O3-SiO2 system, two ternary parameters have been introduced to account for the influence of Al2O3 on Ca-Si interaction and CaO on Al-Si interaction, respectively. The introduction of the ternary parameters resulted in significant improvements in the model description of Al2O3 containing ternary and higher order systems. As a structurally based model, the cell model calculates parameters related to the degree of polymerization in silicate melts. These parameters have been used in a structurally based viscosity model for calculating the viscosity of silicate melts. The fit to a recent set of data has demonstrated the capability of the viscosity model to account closely for the cation effects.