Showing papers on "Binary system published in 2004"

Determination of Physical Properties for the Binary System of 1-Ethyl-3-methylimidazolium Tetrafluoroborate + H2O

Abstract: Experimental data of densities and viscosities are presented for 1-ethyl-3-methylimidazolium tetrafluoroborate + H2O binary systems over the entire range of their compositions at (293.15, 298.15, 303.15, 308.15, 313.15, 318.15, and 323.15) K. Excess molar volumes VE and viscosity deviations Δη have been obtained and fitted to the Redlich−Kister equation. The results show that the densities and viscosities are dependent strongly on water content and weakly on temperature. Comparatively, the viscosity deviation Δη is more sensitive to temperature than the excess molar volume VE.

High-pressure phase behavior of systems with ionic liquids: II. The binary system carbon dioxide+1-ethyl-3-methylimidazolium hexafluorophosphate

Abstract: In this work the phase behavior of a binary mixture consisting of a supercritical fluid and an imidazolium-based ionic liquid (IL) was studied experimentally. Carbon dioxide was selected as the supercritical fluid and 1-ethyl-3-methylimidazolium hexafluorophosphate was considered as the IL. A synthetic method was used to measure vapor–liquid boundaries. Results are reported for carbon dioxide concentrations ranging from 10.4 up to 61.9 mol%, and within temperature and pressure ranges of 308.14–366.03 K and 1.49–97.10 MPa, respectively. Also, the experimental results obtained in this work were compared with other available binary systems of supercritical fluid+IL.

Chemical Compatibility between Silver Electrodes and Low-Firing Binary-Oxide Compounds: Conceptual Study

Abstract: The chemical compatibility of silver electrodes and low-firing ceramics has been considered, in terms of the existence of a tie line between silver (and/or Ag2O) and the binary oxide compound in the corresponding ternary phase diagram. The probability of the existence of the tie line is related to the conditions in the subordinated silver-based isothermal binary systems. Greater probabilities have been calculated for the systems with fewer silver-based binary compounds. Based on the concepts that have been developed, several silver-based isothermal binary systems have been investigated to identify the oxides suitable for the development of low-temperature cofired ceramics. The developed concept has been tested by investigating the phase relations in the Bi2O3–Nb2O5 and Bi2O3–V2O5 ternary systems with silver. X-ray and microstructural investigations of bismuth niobates and bismuth vanadates reveal that, as a result of the inertness of Bi2O3 and the reactivity of Nb2O5 and V2O5 toward silver, compounds that are rich in niobium or vanadium react with silver to form ternary Nb/V-Bi-Ag oxide compounds, whereas for compounds that are rich in bismuth, tie lines to silver and Ag2O do exist.

Diffusion Coefficients for the Binary System Glycerol + Water at 25 °C. A Velocity Correlation Study

Abstract: Diffusion coefficients for the binary system glycerol + water have been studied at 25 °C. Accurate mutual diffusion coefficients have been measured by the Taylor dispersion and Gouy interferometric techniques. Intradiffusion coefficients of both components have been measured by the pulsed gradient spin−echo−Fourier transform NMR technique. The collected diffusion coefficients have been combined with data of water excess chemical potential present in the literature to calculate the velocity correlation coefficients. The results have been interpreted in terms of molecular interactions.

Thermodynamic Assessment of the Gallium‐Oxygen System

Abstract: The experimental information relevant to the Ga-O binary system has been critically assessed. A self-consistent set of Gibbs energy functions describing the phases in this system and a phase diagram are presented for the first time. The adjustable parameters of the models are obtained by a least-squares fit to the experimental data. The liquid phase is described by Hillert's partially ionic liquid model. The gallium oxides (a-, β-, γ-, and δ-Ga 2 O 3 ) are modeled as stoichiometric phases. The gas phase is treated as an ideal solution of the species Ga, Ga 2 , Ga 2 O, GaO, O, O 2 , and O 3 . The calculated phase diagram and thermodynamic properties agree very well with most of the experimental measurements.

Experimental study of the Bi 2 O 3 -Fe 2 O 3 pseudo-binary system

Abstract: As part of a general contribution to the study of accelerator driven system (ADS) nuclear reactor feasibility, a study of the five-component system Bi-Fe-Hg-O-Pb was undertaken. New results about the quasi-binary Bi2O3-Fe2O3 are presented in this paper. The phase diagram was reinvestigated by differential scanning calorimetry, x-ray diffraction, and electron probe microanalysis. A new compound was discovered and characterized: Bi25FeO40. Its crystallographic structure was refined. Invariant and transition temperatures are given, as well as phase compositions.

Chemical Interactions Promoting the ZrO2 Tetragonal Stabilization in ZrO2–SiO2 Binary Oxides

Abstract: Metastable tetragonal ZrO2 phase has been observed in ZrO2–SiO2 binary oxides prepared by the sol–gel method. There are many studies concerning the causes of ZrO2 tetragonal stabilization in binary oxides such as Y3O2–ZrO2, MgO–ZrO2, or CaO–ZrO2. In these binary oxides, oxygen vacancies cause changes or defects in the ZrO2 lattice parameters, which are responsible for tetragonal stabilization. Since oxygen vacancies are not expected in ZrO2–SiO2 binary oxides, tetragonal stabilization should just be due to the difficulty of zirconia particles growing in the silica matrix. Furthermore, changes in the tetragonal ZrO2 crystalline lattice parameters of these binary oxides have recently been reported in a previous paper. The changes of the zirconia crystalline lattice parameters must result from the chemical interactions at the silica–zirconia interface (e.g., formation of Si–O–Zr bonds or Si–O− groups). In this paper, FT-IR and 29Si NMR spectroscopy have been used to elucidate whether the presence of Si–O–Zr or Si–O− is responsible for tetragonal phase stabilization. Moreover, X-ray diffraction, Raman spectroscopy, and transmission electron microscopy have also been used to study the crystalline characteristics of the samples.

Thermodynamic optimization of the Ni–Sn binary system

Abstract: Through the CALPHAD method and based on experimental data of thermodynamic properties and phase boundaries, the phase diagram of the Ni–Sn binary system has been reassessed. The liquid and fcc_A1 (terminal rich nickel solid solution) phases were described by using a simple substitutional model, the excess Gibbs energy being formulated with a Redlich–Kister expression. The other intermediate phases (Ni 3 Sn_HT, Ni 3 Sn 2 _HT, Ni 3 Sn 2 _LT, Ni 3 Sn 4 ), were described with a several sublattice model with different formula; the Gibbs energy of the reference compounds was assumed to be linear, and the binary interaction terms on the sub-lattices to be constant. Ni 3 Sn_LT was treated as a stoichiometric compound. The solubility of Ni in the terminal phase bct_A5(Sn) was neglected because it is very small. Finally a set of self-consistent thermodynamic parameters for all condensed phases in the Ni–Sn binary system was obtained, which can reproduce most of the experimental data.

Solubility of carbon dioxide in dimethylsulfoxide and N-methyl-2-pyrrolidone at elevated pressure

Abstract: Experimental data on the solubility of CO 2 in dimethylsulfoxide (DMSO) and N -methyl-2-pyrrolidone (NMP) are reported at temperatures of 298, 308 and 318 K and pressures approaching the mixture critical point for each binary system The corresponding volumetric expansions of DMSO and NMP with CO 2 are also presented The solubility data are correlated with the Peng–Robinson equation of state (PR-EOS) At a given temperature and pressure, higher solubilities of CO 2 are obtained in NMP compared with DMSO and this trend is consistent with the volumetric expansions of the solvents A plot of the volumetric expansion data as a function of the solubility of CO 2 in the liquid phase suggests that it is unlikely, as a general rule, that the expansion isotherms for the various systems collapse onto a single expansion curve The existence of a single expansion curve appears to hold only for a given binary system over a limited range of temperature The use of two adjustable binary interaction parameters with the PR-EOS provides a superior correlation of the liquid phase composition in comparison with the standard PR-EOS, particularly in the vicinity of the mixture critical point

Phase equilibrium relations in the binary system Bi2O3-ZnO

Abstract: Phase equilibria in the binary system Bi2O3-ZnO were studied by quenching technique. Heat-treated compositions were subjected to X-ray diffraction for phase identification, and differential thermal analysis, optical and scanning electron microscopy were used to determine the solid-liquid equilibria occurring in this system. The data thus obtained revealed that incorporation of a small amount of ZnO to the high-temperature face-centered cubic lattice of Bi2O3 leads to the formation of a body-centered cubic solid solution (γ-Bi2O3), which extends up to a composition of 2.2 mol% ZnO at a temperature near 750°C. On cooling, the γ-Bi2O3 solid solution undergoes a eutectoid transformation at a temperature of 710°C to yield the low-temperature monoclinic polymorph of Bi2O3 (α-Bi2O3) and Bi38ZnO58. The eutectoid occurs at a composition of 1.8 mol% ZnO. The compound Bi38ZnO58 has a crystal structure analogous to the body-centered cubic γ-Bi2O3 solid solution and melts incongruently at a temperature near 753 ± 2°C to yield γ-Bi2O3 and liquid. A binary eutectic occurs between Bi38ZnO58 and ZnO at a composition near 25 ± 1.0 mol% ZnO with a melting temperature of 738 ±2°C. Based on the data obtained in this study, a revised phase diagram of the binary system Bi2O3-ZnO is proposed.

Experimentally Determined Thermochemical Properties of the Malonic Acid/Water System: Implications for Atmospheric Aerosols

Abstract: The liquid/solid phase diagram, solution heat capacities, water activities, enthalpies of fusion, and eutectic temperature of the malonic acid/water binary system have been investigated using differential scanning calorimetry and infrared (IR) spectroscopy of thin films. We report here measurements of the ice melting envelope, malonic acid dissolution envelope, and the ice/malonic acid eutectic temperature and composition in this binary system. We also report the first observation of a malonic acid hydrate, possibly C3H4O4·6H2O, using both thermal analysis and IR spectroscopy. We have observed the formation of this hydrate over a large range of concentrations and determined that it can be a significant fraction of samples within that region. We have also determined the enthalpy of fusion of malonic acid, as well as the constant pressure heat capacities of solutions in the concentration range of 5−55 wt % malonic acid from 323 K down to the freezing point of each solution. Water activities have also been d...

Confinement effect on the adsorption from a binary liquid system near liquid/liquid phase separation.

Abstract: The preferential adsorption of one component of a binary system at the inner surfaces of mesoporous silica glasses was studied in a wide composition range at temperatures close to liquid/liquid phase separation. Confinement effects on the adsorption were investigated by using three controlled-pore glass (CPG-10) materials of different mean pore size (10 to 50 nm). For the experimental system (2-butoxyethanol+water), which exhibits an upper miscibility gap, strong preferential adsorption of water occurs, as the coexistence curve is approached at bulk compositions, at which water is the minority component. In this strong adsorption regime the area-related surface excess amount of adsorbed water decreases with decreasing pore width, while the shift in the volume-related mean composition of the pore liquid shows an opposite trend, i.e., greatest deviation from bulk composition occurring in the most narrow pores. A simple mean-field lattice model of a liquid mixture confined by parallel walls is adopted to rationalize these experimental findings. This model reproduces the main findings of the confinement effect on the adsorption near liquid/liquid phase separation.

Wind Accretion by a Binary Stellar System and Disk Formation

Abstract: I calculate the specific angular momentum of mass accreted by a binary system embedded in the dense wind of a mass losing asymptotic giant branch star. The accretion flow is of the Bondi-Hoyle-Lyttleton type. For most of the relevant parameters space the flow is basically an isothermal high Mach number accretion flow. I find that when the orbital plane of the accreting binary system and the orbital plane of the triple system are not parallel to each other, the accreted mass onto one or two of the binary system components has high specific angular momentum. For a large fraction of triple-star systems, accretion disks will be formed around one or two of the stars in the binary system, provided that the mass ratio of the two stars in the accreting binary system is >0.5. Such disks may blow jets which shape the descendant planetary nebula. The jets' axis will be almost parallel to the orbital plane of the triple-star system. One jet is blown outward relative to the wind, while the other jet pass near the mass losing star, and is more likely to be slowed down or deflected. I find that during the final asymptotic giant branch phase, when mass loss rate is very high, accretion disk may form for orbital separation between the accreting binary systems and the mass losing star of up to 400-800 AU. I discuss the implications for the shape of the descendant planetary nebula, and list several planetary nebulae which may have been shaped by an accreting binary star system, i.e., by a triple star system.

Phase Separation of the B2 Structure Accompanied by an Ordering in Co-Al and Ni-Al Binary Systems

Abstract: The phase separation of the B2 structure in the Co-Al and Ni-Al binary systems has been studied by combining ab initio energetic calculations with the CALPHAD approach. The total energies of the ordered phases based on the bcc lattice were obtained using first-principle band-energy calculations. The cluster expansion method was applied to the results, and the free energies at finite temperatures were calculated for the bcc solid solution. The Co-Al and Ni-Al binary systems were analysed thermodynamically by considering the estimated metastable free energy of the bcc phase. The descriptions of the lattice stability parameters for each pure element were obtained chiefly from the Scientific Group Thermodata Europe (SGTE) datafile. The optimized parameters reasonably reproduced the characteristic features of these binary phase diagrams. The metastable (A2+B2) two-phase field forms in the Co-Al phase diagram, and this equilibrium is closely related to the anomaly in the phase boundaries of the binary system. On the other hand, the phase separation of the A2 and B2 structures are hindered by the presence of the D03 phase in the Ni-Al system. Ground state analysis was performed to clarify the difference in the behaviour of the B2 phase.

Density, Excess Volumes, and Partial Volumes of the Binary Systems of Dimethyl Sulfoxide + Ethyl Acrylate, Butyl Acrylate, Methyl Methacrylate, and Styrene at 298.15 K

Abstract: Densities of the binary systems of dimethyl sulfoxide with ethyl acrylate, butyl acrylate, methyl methacrylate, and styrene have been measured as a function of the composition at 29815 K and atmospheric pressure using an Anton Paar DMA 5000 oscillating U-tube densimeter The calculated excess volumes were correlated with the Redlich–Kister equation and with a series of Legendre polynomials The excess volumes are negative for the four binaries, probably as a result of the large dipole moment of DMSO, becoming smaller as the monomer becomes more branched or longer, and the dipole moment per monomer unit becomes larger