Showing papers on "Ternary operation published in 1990"

Stable and metastable phase equilibria in the chemical interaction between aluminium and silicon carbide

Abstract: An experimental investigation was carried out on the Al-C-Si ternary system under atmospheric pressure and at temperatures up to 1900 K. From the results obtained, a thermodynamic model based on stable and metastable phase equilibria in the Al-C-Si ternary system was set up in order to provide a general description of the chemical interaction between aluminium and SiC. According to this model, aluminium and SiC are in thermodynamic equilibrium at every temperature lower than 923 K. At 923±3 K, i.e. at 10 K below the melting point of pure aluminium, a quasiperitectic invariant transformation occurs in the Al-C-Si system. In this transformation, solid aluminium reacts with SiC to give Al4C3 and a ternary (Al-C-Si) liquid phase. The carbon content of this liquid phase is very low; its silicon content is 1.5±0.4 at%. From 923 to about 1620 K, aluminium partially reacts with an excess of SiC, leading to a metastable monovariant equilibrium involving SiC, Al4C3 and an aluminium-rich (Al-C-Si) ternary liquid phase, L. The carbon content of this liquid phase, L, remains very low whereas its silicon content increases with temperature from 1.5±0.4 at% at 923 K to 16.5±1 at% at 1620 K. In the temperature range 1670 to 1900 K, two other three-phased monovariant equilibria can be reached by reacting aluminium and SiC. These equilibria involve on the one hand SiC, Al4SiC4 and a liquid phase, L′, and on the other hand, Al4SiC4, Al4C3 and a liquid phase, L″. The former is a stable equilibrium, the latter is a metastable one. At temperatures higher than about 2200 K, the latter metastable equilibrium is replaced by two monovariant stable phase equilibria including the ternary carbide Al8SiC7.

Removal of coexisting Pb2+, Cu2+ and Cd2+ ions from water by addition of hydroxyapatite powder.

Abstract: Removal of single, binary and ternary divalent heavy metal ions, i.e., Pb2+, Cu2+ and Cd2+, respectively, from their chloride or nitrate aqueous solutions was studied by the addition of hydroxyapatite in an agitated tank adsorber.The isotherms for each single component were of the rectangular type, i.e., the amounts removed from aqueous phase were constant irrespective of the concentration of solutions. For binary and ternary systems, equilibrium relations were expressed in terms of selectivity coefficient.Concentration decay curves were prepared from experimental data for comparison with theoretical calculations.Regarding mass transfer, it was found that Pb2+ was collected on the apatite structure very fast, while the two other ions showed some resistances other than film diffusion resistance.Furthermore, the apatite structure was studied by X-ray difractometry.

Ternary water in oil microemulsions made of cationic surfactants, water, and aromatic solvents. 2. Droplet sizes and interactions and exchange of material between droplets

Abstract: Ternary water in oil microemulsions made of cationic surfactants, water, and aromatic solvents have been investigated by means of time-resolved fluorescence quenching, quasi-elastic light scattering, and electrical conductivity in order to determine the surfactant aggregation number N per water droplet, the rate constant k{sub e} for the exchange of material between droplets through collisions with temporary merging, the droplet diffusion coefficient D, and the coefficient of interaction between droplets {alpha} and to study the occurrence of electrical percolation as a function of the surfactant chain length, head-group size, and water content of system (expressed as the molar concentration ratio {omega} = (water)/(surfactant)). Most measurements were performed with chlorobenzene as solvent. In one instance, chlorobenzene was substituted by benzene in order to investigate the effect of the nature of the solvent. For a given surfactant, N and k{sub e} increased with {omega} and upon substituting chlorobenzene by benzene. Also, at a given {omega}, N and k{sub e} increased when the surfactant chain length was decreased. The increases of k{sub e} were always extremely large. The droplet hydrodynamic radii from quasi-elastic light scattering were found to agree with the droplet sizes calculated with the N values from fluorescence quenching. The droplet interactionmore » coefficient {alpha} became more negative as the surfactant chain length decreased, indicating increasingly attractive interdroplet interactions. Finally, electrical percolation was found to occur in all systems where interdroplet interactions were sufficiently attractive. The percolation threshold {omega}-values increased with surfactant chain length.« less

Band structure of ternary compound semiconductors beyond the virtual crystal approximation

Abstract: A simple pseudopotential scheme, which incorporates compositional disorder as an effective potential, is proposed for calculation of the band structure of ternary compound semiconductors. It is shown that the present theory, which is free from any additional parameter, satisfactorily produces the band-gap bowings of ternary compounds when the lattice mismatch is small.

XPS study of BN thin films deposited by CVD on SiC plane substrates

Abstract: BN films deposited from a BF3NH3 precursor, under chemical vapour infiltration conditions, on plane sintered α-SiC substrates were analysed by XPS. The films are non-stoichiometric with an N/B atomic ratio of <1. They also contain significant amounts of oxygen atoms, homogeneously distributed in the film and thought to replace partly the nitrogen atoms in the turbostratic hexagonal network. As a result, ternary BNxOy species are formed locally. Near the BN/SiC interface, the oxygen concentration increases owing to the occurrence of ternary SiNxOy species, thought to be the result of an oxinitriding reaction on the substrate surface with the gas phase containing residual oxygen, at the very beginning of the BN deposition process.

Neutron diffraction study of the structural and magnetic properties of the R2Fe17Hx(Dx) ternary compounds (R Ce, Nd and Ho)

Abstract: A structural and magnetic characterization of R2Fe17 alloys and their corresponding hydrides has been carried out by means of powder neutron diffraction. The hydrides have been found to retain the host metal symmetry. Hydrogen is accommodated in rare-earth-rich octahedral and tetrahedral sites. The effects of hydrogenation on the magnetic properties are discussed.

Phase diagrams of ternary gold alloys

Abstract: Published by The Institute of Materials, London. Critical assessments of phase diagram data for 338 gold-based ternary alloys, 114 relevant binaries and 4 appendices of transition, weight and conversion data.

Quaternary, ternary, binary, and pure component sorption on zeolites. 1. Light alkanes on Linde S-115 silicalite at moderate to high pressures

Abstract: Pure component and multicomponent equilibrium adsorption data are reported for the adsorption of the light n-alkanes on Linde 5A and 13X pellets in the temperature range 275-350K and at pressures up to 1.732 MPa but primarily at a pressure of 345 kPa. The intrinsic Henry constants and heats of adsorption are extracted from the data using virial isotherm techniques. The experimental K 0 values for 13X are in excellent agreement with theoretical quantum mechanical calculations. For zeolite 5A, predictions of theoretical pure component, binary, and ternary profiles employing the Ruthven isotherm using intrinsic Henry constants are satisfactory. For 13X zeolite, profile predictions using the Ruthven isotherm require that the intrinsic Henry constant be increased by on average 212% to adequately fit the data. This increase is attributed to the increase in the heat of sorption with loading for these systems

Phase equilibria and crystal chemistry in portions of the system SrO-CaO-Bi2O3-CuO. II: The system SrO-Bi2O3-CuO

Abstract: Symmetry data and unit cell dimensions bases on single crystal and powder x-ray diffraction measurements are reported for all the binary SrO-Bi 2 O 3 phases, including a new phase identified as Sr 6 Bi 2 O 9 . The ternary system contains at least four ternary phases which can be formed in air at ∼900˚C

CMOS ternary logic circuits

Abstract: We review the main difficulties and advantages in developing CMOS ternary circuits. In addition to employing multiple power sources and multiple thresholds, we describe a new theory of transmission functions for designing CMOS ternary logic circuits. It can explain the main CMOS ternary circuits proposed previously. Computer simulations show that the circuits based on the transmission-function theory have more desirable transfer characteristics than ones with resistors.

Thermodynamic properties of hematite — ilmenite — geikielite solid solutions

Abstract: A solution model is developed for rhombohedral oxide solid solutions having compositions within the ternary system ilmenite [(Fe2+sTi4+1−s)A (Fe2+1−sTi4+s)B O3]-geikielite [(Mg2+tTi4+1−t)A (Mg2+1−tTi4+t)B O3]-hematite [(Fe3+)A (Fe3+)B O3]. The model incorporates an expression for the configurational entropy of solution, which accounts for varying degrees of structural long-range order (0≤s, t≤1) and utilizes simple regular solution theory to characterize the excess Gibbs free energy of mixing within the five-dimensional composition-ordering space. The 13 model parameters are calibrated from available data on: (1) the degree of long-range order and the composition-temperature dependence of the\(R\bar 3c - R\bar 3\) transition along the ilmenite-hematite binary join; (2) the compositions of coexisting olivine and rhombohedral oxide solid solutions close to the Mg−Fe2+ join; (3) the shape of the miscibility gap along the ilmenite-hematite join; (4) the compositions of coexisting spinel and rhombohedral oxide solid solutions along the Fe2+−Fe3+ join. In the course of calibration, estimates are obtained for the reference state enthalpy of formation of ulvospinel and stoichiometric hematite (−1488.5 and −822.0 kJ/mol at 298 K and 1 bar, respectively). The model involves no excess entropies of mixing nor does it incorporate ternary interaction parameters. The formulation fits the available data and represents an internally consistent energetic model when used in conjuction with the standard state thermodynamic data set of Berman (1988) and the solution theory for orthopyroxenes, olivines and Fe−Mg titanomagnetite-aluminate-chromate spinels developed by Sack and Ghiorso (1989, 1990a, b). Calculated activity-composition relations for the end-members of the series, demonstrate the substantial degree of nonideality associated with interactions between the ordered and disordered structures and the dominant influence of the miscibility gap across much of the ternary system. The predicted shape of the miscibility gap, and the orientation of tie-lines relating the compositions of coexisting phases, display the effects of coupling between the excess enthalpy of solution and the degree of long-range order. One limb of the miscibility gap follows the composititiontemperature surface corresponding to the ternary\(R\bar 3 - R\bar 3c\) second-order transition.

Glass formation in ternary transition metal alloys

Abstract: The authors have recently used a combination of classical elasticity theory and Miedema's model for the heat of formation of alloys to predict the glass-forming ranges of binary transition metal systems. In this paper they extend this approach to study the glass-forming regions in the ternary case. The predictions of the theory are compared with available experimental information for some Co-based ternary alloys, and they relate their treatment to the empirical equation recently proposed by Ueno and Waseda (1985) to describe the minimum solute concentration for glass formation in ternary systems.

Ternary intermetallics in aluminiumrefractory metal-X systems (X = V, Cr, Mn, Fe, Co, Ni, Cu, Zn)

Abstract: The phase equilibria of aluminium containing ternary systems are reviewed with particular emphasis on the structure, composition, and stability of the intermetallic compounds present in these systems. The ternary systems are of the type AI-refractory metal (Ti, Zr, Hf, V, Nb, Ta, Mo)-X (X = V, Cr, Mn, Fe, Co, Ni, Cu, Zn), with the majority of the information originating from Soviet and German literature. Inconsistencies between the results of various investigations are highlighted when such comparison is at all possible, although frequently only a single source is available. Potential ternary intermetallics of interest are discussed based on their density, crystal structure, melting point, and compositional range of existence. A trend is noted in the crystal structure of Al3X-type compounds as a function of the location of the constituent elements in the periodic table. In the last section of this review, current theoretical approaches for predicting crystal structure stability and phase diagrams ...

RMX compounds formed by alkaline earths, europium and ytterbium—I. Ternary phases with M ≡ Cu, Ag, Au; X ≡ Sb, Bi

Abstract: 19 intermetallic compounds with the general formula RMX (R ≡ Ca, Sr, Ba, Eu, Yb; M ≡ Cu, Ag, Au; X ≡ Sb, Bi) were synthesized and structurally studied by X-ray methods on powders and single crystals. The ternary phases crystallize in four ordered structural types: ZrBeSi, LiGaGe, TiNiSi and MgAgAs. Some comments are given on the parameters controlling the structure of these phases, and the volume effects are calculated.

Thermodynamic properties of compound-forming liquid alloys

Abstract: The experimentally determined properties of compound-forming liquid alloys show specific concentration and temperature dependences, which are caused by the existence of chemical short range order in these alloys. The concentration and temperature dependences of thermodynamic mixing functions are explained on the basis of homogeneous equilibria reactions within an association model for a simple description of chemical short range order. The ability of this model to predict thermodynamic properties of a binary liquid alloy from experimental results and to extrapolate it to ternary liquid alloys is demonstrated.

Effect of Composition on the Electrocatalytic Activity of the Ternary Oxide Ru0.3Ti ( 0.7 − x ) Sn x O 2 I . Oxygen Evolution from Solutions

Abstract: The electrocatalytic activity of ternary oxides of general formula Ru 0.3 Ti (0.7−x )Sn x O 2 for O 2 evolution from HClO 4 solution has been studied as a function of x by current-potential curves and reaction order determination. The surface state of the electrodes has been monitored by voltammetric curves before and after each run of experiments

Densities and viscosities of binary and ternary liquid systems containing xylenes

Abstract: Experimental measurements of density and viscosity of three binary systems, viz., p-xylene/m-xylene, p-xylene/o-xylene, and m-xylene/o-xylene, were performed over the complete concentration ranges, for temperatures between 273.15 and 303.15 K. Experimental densities were compared with those predicted by the Hankinson-Brobst-Thomson method, showing average deviations of about 0.3%. The viscosity data were correlated by the McAllister equations, producing excellent representations of both binary and ternary data

Electron‐optical‐phonon interaction in binary/ternary heterostructures

Abstract: The macroscopic dielectric continuum model is used to derive electron‐optical‐phonon interaction Hamiltonians for binary/ternary heterostructures containing both single and double heterointerfaces. The formulation presented in this work leads to a general prescription for the calculation of mode‐strength coefficients in ternary‐containing heterostructures. An illustration of these results is provided by exhibiting the mode strengths of the interaction Hamiltonians for the interface and the half‐space longitudinal optical modes in a GaAs/AlyGa1−yAs single heterostructure.

Synthesis, structure, and properties of a new ternary metal nitride, Ca3CrN3

Abstract: : We have synthesized a new ternary nitride, Ca3CrN3 (calcium chromium nitride), from the binary nitrides at high temperature. The refined structure was solved in the Cmcm space group with lattice constants a=8.503(2), b=10. 284(2), c=5.032(1), and R=3.9%, R(w)=3.9%. This new structure type consists of sheets of (CrN3)6(-) planar triangular units and calcium ions. Ca3CrN3 is insulating and paramagnetic with Cr3(+) in the low spin state. This is the first unambiguous example of low spin Cr3(+). Larger than expected antiferromagnetic interactions produce a maximum in the magnetic susceptibility at 245K, even though the shortest Cr-Cr distance is 4.73A. (jg)