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Computer modeling of gas-condensed phase equilibria: present status and some future needs in science and technology

Description: Possible uses for computer calculations of equilibria between high-temperature multicomponent vapors and condensed phases lie in coal combustion cosmochemistry, fuel cells, etc. Some of the computer capabilities which would be useful are deduced. (DLC)
Date: January 1, 1978
Creator: Blander, M.
Partner: UNT Libraries Government Documents Department

Refractory metal particles in refractory inclusions in the Allende meteorite

Description: An examination of refractory metal particles in five calcium-aluminum-rich inclusions in the Allende meteorite indicates a complex variety of compositions and large departures from equilibrium. These particles appear to have been primordial condensates which were isolated from the nebula and from each other at different times by cocondensing oxides. Selective diffusion and/or oxidation of the more oxidizable metals (Mo, W, Fe and Ni), phase segregations into different alloy phases (fcc, bcc, hcp and perhaps ordered phases) and the formation of metastable condensates appears to have been involved in the modification of these materials to their present state. Only a small fraction of our observations cannot be reconciled with this picture because of a lack of knowledge of some of the phase equilibria which might have bee involved.
Date: January 1, 1980
Creator: Fuchs, L.H. & Blander, M.
Partner: UNT Libraries Government Documents Department

Computer-assisted analyses of the thermodynamic properties of slags in coal-combustion systems

Description: Equations were developed for the analysis of the thermodynamic properties of molten silicate solutions; the equations take into account the unusual concentration and temperature dependence of the solution properties of ordered systems. For binary systems, these equations were coupled with an optimization computer program to analyze all reliable thermodynamic data, including phase diagrams, free energies and enthalpies of formation of compounds, activities of components, enthalpies of mixing, entropies of fusion, miscibility gaps, etc. In this manner, we analyzed data for five binary systems: CaO-SiO/sub 2/, Na/sub 2/O-SiO/sub 2/, CaO-Al/sub 2/O/sub 3/, Na/sub 2/O-Al/sub 2/O/sub 3/, and Al/sub 2/O/sub 3/-SiO/sub 2/. The results of the binary systems were combined, and an analysis done of three ternary systems: CaO-Al/sub 2/O/sub 3/-SiO/sub 2/, Na/sub 2/O-CaO-SiO/sub 2/, and Na/sub 2/O-Al/sub 2/O/sup 3/-SiO/sub 2/. A tentative analysis of the quaternary system, Na/sub 2/O-CaO-Al/sub 2/O/sub 3/-SiO/sub 2/, was also undertaken. 53 references, 51 figures, 3 tables.
Date: September 1, 1983
Creator: Blander, M. & Pelton, A.D.
Partner: UNT Libraries Government Documents Department

Theoretical concepts useful in the calculation or storage of phase diagrams of ionic systems

Description: Equations for the a priori calculation or for the storage of phase diagrams and thermodynamic properties of molten ternary ionic systems were derived from the conformal ionic solution theory, which rigorously takes into account the ionic nature of the melts. Thermodynamic functions for ternary ionic systems were derived for cases in which all the cations have the same charge and all the anions have the same charge. Equations for the excess free energy of mixing, ..delta..G/ sup E/, are obtained for reciprocal systems, e.g., A/sup +/, B/sup +//X/sup -/, Y/sup -/, defined by the three components AY, BX, and BY, and for additive systems, e.g., A/sup +/, B/sup +/, C/sup +//X/sup -/. From these equations and classical thermodynamic relations, one can calculate phase diagrams of the two classes of ternary systems a priori from data on the lower order systems. Comparisons of such calculations with experimental data were made for liquidus phase diagrams and miscibility gaps in a number of ternary systems; the agreement was generally very good. An empirical extension of the theory to a broader range of systems, in which a pair of cations or anions have different charges, led to a good representation of the phase diagrams. The success of these calculations indicates their usefulness in evaluating the self-consistency of measurements and in the extrapolation of data into unmeasured regions. The equations should also prove useful for the storage of phase diagrams. The accuracy of such stored information can be improved by treating the coefficients as somewhat adjustable parameters and by adding more terms.
Date: January 1, 1977
Creator: Saboungi, M. L. & Blander, M.
Partner: UNT Libraries Government Documents Department

Dimensional analysis of partition functions for ionic molecules: thermodynamic properties of vapors

Description: A dimensional analysis of the classical partition functions of vapors of ionic molecules leads to expressions for the relative values of thermodynamic properties for molecules having one type of cation and one type of anion. Relative values of standard entropies, S/sup 0/, and of free energy functions, (G/sup 0/--H/sup 0//sub 0/)/T, can be calculated with a knowledge of the cation-anion distance, the atomic masses, and the electronic partition function. The theory is not expected to be valid for energies and enthalpies. Comparisons of the theoretical predictions with data on S/sup 0/ and (G/sup 0/--H/sup 0//sub 0/)/T for a large number of diatomic molecules and their associated dimers demonstrate the accuracy of this simple calculation. Covalent molecules fit the expressions derived for ionic molecules surprisingly well indicating that the equations might be more general than implied by the model. The model should be most useful for polyatomic molecules, M/sub m/X/sub x/, where m and/or x is greater than unity. The theory minimizes the amount of spectroscopic and structural information necessary to calculate some of the thermodynamic properties since functions such as S/sup 0/ and (G/sup 0/--H/sup 0//sub 0/)/T can be calculated for molecules of a given type if the corresponding data for one member of the class are well known.
Date: January 1, 1978
Creator: Frurip, D.J. & Blander, M.
Partner: UNT Libraries Government Documents Department

The coordination cluster theory for metallic solutions

Description: The coordination cluster theory for the thermodynamic properties of a dilute solute in a binary or higher order solvent. Although the CCT has been applied to liquids, it can be modified for solids. The theory permits one to describe the thermodynamic properties of a solute in a binary solvent in terms of the solute properties in the pure solvent components, the properties of the binary mixture and one unknown parameter. In principle, the properties of solutes in multicomponent solvents can be calculated from those in the subsidiary binary solvents. Modern quantum mechanical methods for the calculation of the energetics of metal solutions could be used to place the theory on a firm fundamental basis by testing the approximations in the theory and determining the unknown parameters. 9 refs., 3 figs.
Date: December 1, 1987
Creator: Blander, M. & Saboungi, M.L.
Partner: UNT Libraries Government Documents Department

Equations of state for alkali metals near their critical points

Description: Equations of state of alkali metals which provide a good representation of the thermodynamic properties of alkali metals, especially up to their critical temperatures and beyond, and also have a form consistent with quantum mechanical theory are discussed. (GHT)
Date: January 1, 1977
Creator: Blander, M. & Leribaux, H. R.
Partner: UNT Libraries Government Documents Department

Removal of copper from carbon-saturated steel with an aluminum sulfide/iron sulfide slag

Description: Scrap iron and steel has long been considered a resource in the steel-making industry, and its value is largely determined by its impurity content. As the mini-mills, the major consumers of scrap iron and steel, expand into producing flat-rolled sheet, the demand for high-quality scrap will increase. Of the impurities present in scrap, copper is particularly troublesome because of its role in causing hot shortness. Therefore, the copper content of scrap should be kept below {approx} 0.1 wt%. A method for removing copper from steel could be used to improve the quality of scrap and make it more available for use by mini-mills. To determine the effectiveness of a binary slag consisting of aluminum sulfide and iron sulfide on the removal of copper from steel and iron, the distribution coefficient of copper between the slag and a carbon-saturated iron melt was investigated at 1,365 C. The composition of the slag was varied from nearly pure aluminum sulfide to pure iron sulfide. A maximum distribution coefficient of 30 was found, and the copper level in the iron melt was reduced to as low as 0.07 wt.% with a 4:1 ratio of iron to slag.
Date: December 1, 1995
Creator: Cohen, A. & Blander, M.
Partner: UNT Libraries Government Documents Department

A theory for correlating the thermodynamic and structural properties of molten silicate solutions

Description: A theory of molten silicates is presented which takes into account the dependence of the free energy of cutting Si-O-Si bridging bonds on local structures of the two silicons in the bond. Resultant equations describe the thermodynamic properties of primary silicate solutions containing a mixture of bridges and cut bridges, and should ultimately provide a realistic measure of the distribution of silicon species which have i cut bridges (i = 1,2,3,4) from analyses of thermodynamic data.
Date: June 1, 1995
Creator: Blander, M. & Bloom, I.
Partner: UNT Libraries Government Documents Department

Chemistry of Gaseous and Condensed Products in Coal Combustion and Conversion Systems

Description: A recently developed computer program, based on geometric programming, was used to evaluate the chemistry of gaseous and condensed products that arise in conversion of Illinois bituminous coal under both oxidizing and reducing conditions.
Date: August 1989
Creator: Sinha, S. N.; Natesan, K. & Blander, M.
Partner: UNT Libraries Government Documents Department

Analyses and predictions of the thermodynamic properties and phase diagrams of silicate systems

Description: Molten silicates are ordered solutions which can not be well represented by the usual polynomial representation of deviations from ideal solution behavior (i.e. excess free energies of mixing). An adaptation of quasichemical theory which is capable of describing the properties of ordered solutions represents the measured properties of binary silicates over broad ranges of composition and temperature. For simple silicates such as the MgO-FeO-SiO{sub 2} ternary system, in which silica is the only acid component, a combining rule generally leads to good predictions of ternary solutions from those of the binaries. In basic solutions, these predictions are consistent with those of the conformal ionic solution theory. Our results indicate that our approach could provide a potentially powerful tool for representing and predicting the properties of multicomponent molten silicates.
Date: July 1, 1992
Creator: Blander, M.; Pelton, A. & Eriksson, G.
Partner: UNT Libraries Government Documents Department

On the origin of porphyritic chondrules

Description: A computer program for the complex equilibria in a cooling nebular gas was used to explore a possible origin of porphyritic chondrules, the major class of chondrules in chondritic meteorites. It uses a method of accurately calculating the thermodynamic properties of molten multicomponent aluminosilicates, which deduces the silicate condensates vs temperature and pressure of a nebular gas. This program is coupled with a chemical equilibrium algorithm for systems with at least 1000 chemical species; it has a data base of over 5000 solid, liquid, and gaseous species. Results are metastable subcooled liquid aluminoscilicates with compositions resembling types IA and II porphyritic chondrules at two different temperatures at any pressure between 10{sup {minus}2} and 1 (or possibly 10{sup {minus}3} to 5) atm. The different types of chondrules (types I, II, III) could have been produced from the same gas and do not need a different gas for each apparent oxidation state; thus, the difficulty of current models for making porphyritic chondrules by reheating different solids to just below their liquidus temperatures in different locations is not necessary. Initiation of a stage of crystallization just below liquidus is part of the natural crystallization (recalescence) process from metastable subcooled liquidus and does not require an improbably heating mechanism. 2 tabs.
Date: May 1, 1994
Creator: Blander, M.; Unger, L.; Pelton, A. & Ericksson, G.
Partner: UNT Libraries Government Documents Department

A possible origin of EL6 chondrites from a high temperature-high pressure solar gas

Description: Condensates from a gas of ``solar`` composition were calculated to investigate the origins of EL6 chondrites using a free energy minimization program with a data base for the thermodynamic properties of multicomponent molten silicates as well as for other liquids solids, solid solutions and gaseous species. Because of high volatility of silicon and silica, the high silicon content of metal (2.6 mole %) can only be produced at pressures 10{sup {minus}2} atm at temperatures above 1475 K. At 100--500 atm, a liquid silicate phase crystallizes at a temperature where the silicon content of the metal, ferrosilite content of the enstatite and albite concentration in the plagioclase are close to measured values. In pyrometallurgy, liquid silicates are catalysts for reactions in which Si-O-Si bridging bonds are broken or formed. Thus, one attractive mode for freezing in the compositions of these three phases is disappearance of fluxing liquid. If the plagioclase can continue to react with the nebula without a liquid phase, lower pressures of 10{sup {minus}1} to 1 atm might be possible. Even if the nebula is more reducing than a solar gas, the measured properties of EL6 chondrites might be reconciled with only slightly lower pressures (less than 3X lower). The temperatures would be about the same as indicated in our calculations since the product of the silicon content of the metal and the square of the ferrosilite content of the enstatite constitute a cosmothermometer for the mineral assemblage in EL6 chondrites.
Date: May 1, 1994
Creator: Blander, M.; Unger, L.; Pelton, A. & Eriksson, G.
Partner: UNT Libraries Government Documents Department

Correlations between structure, spectra, and thermodynamics in solutions of cobalt chloride in sodium tetrachloroaluminates

Description: An EMF technique using the cell Co/CoCl{sub 2} {minus} Na AlCl{sub 4}//(AgCl)x {minus} NaAlCl{sub 4} (x fixed)/Ag was used to measure the solubility of CoCl{sub 2} in NaCl{center dot}AlCl{sub 3} melts. The changes in EMF as a function of changes in melt composition were correlated with changes in the UV-Vis spectra of the dissolved cobalt species. From these data the microscopic structural contributions to the macroscopic thermodynamic properties of the solutions were estimated. 14 refs., 5 figs., 1 tab.
Date: January 1, 1990
Creator: Newman, D.S.; Tumidajski, P.J. & Blander, M.
Partner: UNT Libraries Government Documents Department

Thermodynamic behavior of high-T sub c oxide systems via EMF and related measurements

Description: EMF measurements of oxygen fugacities as a function of stoichiometry have been made in the YBa{sub 2}Cu{sub 3}O{sub x}, and NdBa{sub 2}Cu{sub 3}O{sub x}, and Nd{sub 1.81}Ce{sub 0.19}CuO{sub x} superconducting systems in the temperature range 400--750{degree}C by means of an oxygen titration technique with an yttria-stabilized zirconia electrolyte. The object of our current measurements is to investigate the effect of ionic size of Y, Gd and Nd on the thermodynamic behavior and structural transition in the LnBa{sub 2}Cu{sub 3}O{sub x} system. The shape of the 400{degree}C isotherm for NdBa{sub 2}Cu{sub 3}O{sub x} suggests the presence of a miscibility gap at lower temperatures, at values of x that are higher than those in the YBa{sub 2}Cu{sub 3}O{sub x} system. The locations of the miscibility gaps are consistent with the effects of ionic radii on the composition dependence of {Tc} for these systems. Our results explain the two plateaus in measured value of {Tc} as a function of composition for the YBa{sub 2}Cu{sub 3}O{sub x} system and appear to be consistent with the less pronounced {Tc} plateaus found for the NdBa{sub 2}Cu{sub 3}O{sub x} system higher stoichiometry values. For a given oxygen stoichiometry, partial pressures of oxygen above NdBa{sub 2}Cu{sub 3}O{sub x} are higher than for the YBa{sub 2}Cu{sub 3}O{sub x} system in accord with calculated partial molar thermodynamic quantities. The results of limited measurements on the n-type (electron-doped) superconducting Nd{sub 1.81}Ce{sub 0.19}CuO{sub x} system will be presented. A thermodynamic assessment and intercomparison of our oxygen partial pressure measurements with the results of other measurements will be presented. 34 refs., 9 figs., 1 tab.
Date: January 1, 1991
Creator: Tetenbaum, M.; Tumidajaski, P.; Bloom, I.D.; Brown, D.L. & Blander, M.
Partner: UNT Libraries Government Documents Department

Chemical Engineering Division Basic Energy Sciences Research: July 1976-September 1977

Description: Studies in basic energy science covered many different activities, nearly all of which were designed to gain information required for a better understanding of systems important to national needs in energy and environment. Studies of associating gases included measurements of thermal conductivities and basic molecular orbital calculations. Raman spectroscopy and spectrophotometry were used to determine thermodynamic and spectroscopic data on salt vapor complexes. Polarized Raman spectra of As2S3 thin films and vapors were recorded. Halogenation of lanthanide oxides with aluminum chloride allowed the separation of the resultant chloride complexes by vapor transport. Electrochemical titrations were used to obtain the solubility product of iron sulfide in molten LiCl-KCl eutectic. Solubility products of eleven sulfides in the same eutectic mixture were calculated. Galvanostatic techniques were used to study metal deposition/dissolution reactions in molten salts. Activity coefficients of lithium in lithium-lead alloys were determined electrochemically; phase diagrams of ternary alloys of Li-Al-Mg and Li-Ca-Mg were computed. Thermodynamic studies are being made of the sorption of hydrogen by Li-Al and Li-Pb alloys. The study of the solubility of oxygen in liquid lithium was completed. An electric resistance method for measuring distribution properties of nonmetallic elements in binary metallic systems containing lithium is being developed. Calorimetric methods were used to measure standard enthalpies of formation of some coal components, lanthanum and rare earth trifluorides, and gamma-UO3, UF6, Cs3CrO4, Cs4CrO4, As4S4, and As2S3. High-temperature enthalpy increments were measured for LaF3 and beta-As4S4. The acidities of airborne ammonium sulfate-bearing particles from various areas of the U.S. were measured using Fourier-transform infrared spectroscopy.
Date: 1978?
Creator: Cafasso, F. A.; Blander, M.; Maroni, V. A.; Johnson, C. E.; Kumar, R. & Siegel, S.
Partner: UNT Libraries Government Documents Department

Chemical Engineering Division physical inorganic chemistry. Annual report, July 1975--June 1976

Description: The thermal conductivity of acetonitrile vapor has been measured at temperatures between 338 and 387/sup 0/K and pressures between 100 and 1050 torr. The pressure dependence of the thermal conductivities indicates the presence of dimeric vapor species with an association constant given by RT ln K/sub 2/ (atm/sup -1/) = 5002 - 21.15 T. Molecular orbital studies of hydrogen-bonded methyl alcohol vapor complexes indicate that, the cyclic tetramer is especially stable. Preliminary calculations on trifluoroethanol indicate that its dimer is more stable than that of methanol. Molecular dynamics calculations have been utilized to calculate the second-order coefficient of conformal ionic solution (CIS) theory. The results indicate that the repulsive part of the pair potential most commonly used for calculations on molten salts is inaccurate and that calculation of the CIS coefficient provides a sensitive test of pair potentials. Laser-Raman spectra of molten solutions of YCl/sub 3/ in CsCl, KCl and LiCl were obtained and compared with spectra of solids of known structure. The spectra at low concentrations of YCl/sub 3/ (X/sub YCl/sub 3// is less than 0.25) indicate an octahedrally coordinated YCl/sub 6//sup 3 -/ species. Raman and infrared spectra of claudetite and arsenolite were measured and compared with the spectra of vitreous and liquid As/sub 2/O/sub 3/, as well as with the As/sub 4/O/sub 6/ vapor molecules.The spectrum of claudetite has some resemblance to that of vitreous and liquid As/sub 2/O/sub 3/. Raman spectra of arsenous oxide indicate that the dimeric As/sub 2/O/sub 3/ species is present. The Raman spectra of aluminum chloride vapor (AlCl/sub 3/ and Al/sub 2/Cl/sub 6/ vapor molecules), provided nine new bands not observed before and permitted a more complete assignment and analysis of the structure of the species to be made. The Raman spectra of In(I), In(II) and In(III) chlorides indicate the presence of ...
Date: January 1, 1976
Creator: Blander, M.; Curtiss, L. A.; Hsu, C. C.; Kucera, G. H.; Marr, J. J.; Papatheodorou, G. N. et al.
Partner: UNT Libraries Government Documents Department

Analyses and predictions of the thermodynamic properties and phase diagrams of silicate systems

Description: Molten silicates are ordered solutions which can not be well represented by the usual polynomial representation of deviations from ideal solution behavior (i.e. excess free energies of mixing). An adaptation of quasichemical theory which is capable of describing the properties of ordered solutions represents the measured properties of binary silicates over broad ranges of composition and temperature. For simple silicates such as the MgO-FeO-SiO{sub 2} ternary system, in which silica is the only acid component, a combining rule generally leads to good predictions of ternary solutions from those of the binaries. In basic solutions, these predictions are consistent with those of the conformal ionic solution theory. Our results indicate that our approach could provide a potentially powerful tool for representing and predicting the properties of multicomponent molten silicates.
Date: January 1, 1992
Creator: Blander, M. (Argonne National Lab., IL (United States)); Pelton, A. & Eriksson, G. (Ecole Polytechnique, Montreal, PQ (Canada). Dept. of Metallurgy and Materials Engineering)
Partner: UNT Libraries Government Documents Department