Ternary ionic systems

In ionic materials, where broadening of the central transition is dominated by CSA, the chemical shift tensor can be characterised. The CSA values for such compounds are summarised in Table 6.4. The chemical shift tensors in the titanates tend to have larger spans than the zirconates, reflecting the influence of the B cation on the CS tensor. 

Many oxides have properties such as ionic conductivity, making them suitable for use as solid electrolytes and oxygen sensors. These properties depend on ionic motion in the material and can be studied by 0 NMR. Such a study has been made between room temperature and 1200°C of Ba2ln205 which contains three inequivalent oxygen sites 

The solid state chemistry of mixed oxide systems can be directly probed by O NMR. The formation of nanocrystalline Ti02 has been studied by doping the system 

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Ternary ionic systems contain four kinds of ions, which can be constituted in three different ways (A+, B+, C+/X ), (A+ZX", Y , Z ), or (A" ", B+/X , Y ). The first two arrangements are additive ternary systems (the former one is a system with a common anion, the latter one is a system with a common cation), while the last one is a ternary reciprocal system. Having in mind the restriction of electro-neutrality, there are only three independent salt components, from which the solution could be built up. 

A ternary reciprocal system is a system containing four components, but where these components are related through a reciprocal reaction. One example is the system LiCl-LiF-KCl-KF. Solid LiCl, LiF, KC1 and KF are highly ionic materials and take the rock salt crystal structure, in which the cations and anions are located on separate sub-lattices. It is therefore convenient to introduce ionic fractions (Xj) for each sub-lattice as discussed briefly in Section 3.1. The ionic fractions of the anions and cations are not independent since electron neutrality must be fulfilled ... 

A wide variety of data for mean ionic activity coefficients, osmotic coefficients, vapor pressure depression, and vapor-liquid equilibrium of binary and ternary electrolyte systems have been correlated successfully by the local composition model. Some results are shown in Table 1 to Table 10 and Figure 3 to Figure 7. In each case, the chemical equilibrium between the species has been ignored. That is, complete dissociation of strong electrolytes has been assumed. This assumption is not required by the local composition model but has been made here in order to simplify the systems treated. 

Two activity coefficient models have been developed for vapor-liquid equilibrium of electrolyte systems. The first model is an extension of the Pitzer equation and is applicable to aqueous electrolyte systems containing any number of molecular and ionic solutes. The validity of the model has been shown by data correlation studies on three aqueous electrolyte systems of industrial interest. The second model is based on the local composition concept and is designed to be applicable to all kinds of electrolyte systems. Preliminary data correlation results on many binary and ternary electrolyte systems suggest the validity of the local composition model. 

This chapter commences with a review of a limited number of ternary hydride systems that have two common features. First, at least one of the two metal constituents is an alkali or alkaline earth element which independently forms a binary hydride with a metal hydrogen bond that is characterized as saline or ionic. The second metal, for the most part, is near the end of the d-electron series and with the exception of palladium, is not known to form binary hydrides that are stable at room temperature. This review stems from our own more specific interest in preparing and characterizing ternary hydrides where one of the metals is europium or ytterbium and the other is a rarer platinum metal. The similarity between the crystal chemistry of these di-valent rare earths and Ca2+ and Sr2+ is well known so that in our systems, europium and ytterbium in their di-valent oxidation states are viewed as pseudoalkaline earth elements. 

The discussion up to this point has been concerned essentially with metal alloys in which the atoms are necessarily electrically neutral. In ionic systems, an electric diffusion potential builds up during the spinodal decomposition process. The local gradient of this potential provides an additional driving force, which acts upon the diffusing species and this has to be taken into account in the derivation of the equivalents of Eqns. (12.28) and (12.30). The formal treatment of this situation has not yet been carried out satisfactorily [A.V. Virkar, M. R. Plichta (1983)]. We can expect that the spinodal process is governed by the slower cation, for example, in a ternary AX-BX crystal. The electrical part of the driving force is generally nonlinear so that linearized kinetic equations cannot immediately be applied. 

Until recently, the synthesis of ionic/covalent nitrides was relatively unexplored except for the pioneering work of Juza on ternary lithium nitrides.11 However, within the last decade, several groups have begun to explore ternary nitride systems, many of which have relied on the inductive effect. The inductive effect is based on the donation of electron density from an electropositive element to an adjacent metal-nitrogen bond, thereby increasing the covalency and stability of that bond and of the nitride material itself. The success of this method is illustrated by the fact that almost all of the known ionic/covalent ternary nitrides contain electropositive elements. Only recently has a small number of transition metal ternary nitrides been synthesized in the absence of the inductive effect at moderate temperatures, by taking advantage of low temperature techniques, such as the ammonolysis of oxide precursors and metathesis reactions.6,12-17... 

From a global assessment of these results, it seems inescapable to conclude that mean-field behavior does not remain valid asymptotically close to the critical point. Rather, ionic systems seem to show Ising-to-mean-field crossover. Such a crossover has been a recurring result observed near liquid-liquid consolute points in Coulombic electrolyte solutions, in ternary aqueous electrolyte solutions containing an organic cosolvent, and in binary aqueous solutions of NaCl near the liquid-vapor critical line. 

For ternary catalyst systems a vast number of halide donors was investigated which renders a complete quotation impossible. It is important to note, however, that for a given halide, the actual halide source neither has a strong influence on catalyst activity nor on cis- 1,4-contents. As halogen sources which are found in the literature cover the whole range from ionic halides to covalently bound halogen atoms the strength by which the halide is bound to the donor is not a critical factor. 

In our laboratories, extensive use has been made of vapor pressure (14-18) and membrane methods ( 2, 3, 19, 20) to Infer thermodynamic results for ternary aqueous systems containing an ionic or a nonionic surfactant and an organic solute. The most precise solubilization measurements ever reported have been obtained with an automated vapor pressure apparatus for volatile hydrocarbon solutes such as cyclohexane and benzene, dissolved In aqueous solutions of sodium octylsulfate and other Ionic surfactants (15, 16). A manual vapor pressure apparatus has been employed to obtain somewhat less precise results for solutes of lower volatility (17, 18). Recently, semi-equilibrium dialysis (19, 20) and MEUF (2) methods have been used to investigate solute-surfactant systems in which the organic solubilizates are too involatile to study by ordinary vapor pressure methods. 

When the ternary ionic compound that we are trying to name contains a cation (positive ion) with multiple oxidation states, we still need to employ the stock system. For example, if we were asked to name the compound with the formula Cu(N03)2, we would determine that the oxidation number of the copper must be +2, because there are two nitrate ions, each with a charge of -1, and +2 + 2(-l) = 0. This would give us the name copper (II) nitrate for this compound. 

The phase behaviour of the pseudo-ternary ionic mixture can again be explained with the interplay of the three binary base systems. At low temperatures the ionic surfactant is... 

Ionic surfactants with only one alkyl chain are generally extremely hydrophilic so that strongly curved and thus almost empty micelles are formed in ternary water-oil-ionic surfactant mixtures. The addition of an electrolyte to these mixtures results in a decrease of the mean curvature of the amphiphilic film. However, this electrolyte addition does not suffice to drive the system through the phase inversion. Thus, a rather hydrophobic cosurfactant has to be added to invert the structure from oil-in-water to water-in-oil [7, 66]. In order to study these complex quinary mixtures of water/electrolyte (brine)-oil-ionic surfactant-non-ionic co-surfactant, brine is considered as one component. As was the case for the quaternary sugar surfactant microemulsions (see Fig. 1.9(a)) the phase behaviour of the pseudo-quaternary ionic system can now be represented in a phase tetrahedron if one keeps temperature and pressure constant. 

Examination of ternary systems (containing the emusifying wax and water but no oil phase) by X-ray diffraction indicates that, for all emulsifying systems, addition of water causes swelling of the interlamellar spaces. Ionic emulsifying systems possess a greater capacity to swell than non-ionic systems. Swelling in ionic systems is an electrostatic phenomenon, whereas that... 

The Margules expansion model has been tested on some ionic systems over very wide ranges of composition, but over limited ranges of temperature and pressure (33,34). In this study, the model is applied over a wider range of temperature and pressure, from 25-350 C and from 1 bar or saturation pressure to 1 kb. NaCl and KCl are major solute components in natural fluids and there are abundant experimental data from which their fit parameters can be evaluated. Models based on the ion-interaction ajiproach are available for NaCl(aq) and KCl(aq) (8,9), but these are accurate only to about 6 molal. Solubilities of NaCl and KCl in water, however, reach 12 and 20 m, respectively, at 350 C, and ionic strengths of NaCl-KCl-H20 solutions reach more than 30 m at this temperature (35). The objective of this study is to describe the thermodynamic properties, particularly the osmotic and activity coefficients, of NaCl(aq) and KCl(aq) to their respective saturation concentrations in binary salt-H20 mixtures and in ternary NaCl-KCl-H20 systems, and to apply the Margules expansion model to solubility calculations to 350 C. 

The phase behavior to be discussed in the following is the simplest ternary case presented by Winsor over 40 years ago [11], in which the amphiphile is either a pure surfactant or, as often in ionic systems, a mixture of surfactant and alcohol, which can be considered a pseudo-component, because the surfactant and alcohol behave in a collective way as far as their affinities of the oil and water phases are concerned. This is often the case with an intermediate alcohol such as 5 -butanol. 

The fixed composition is tyirically selected so that the representative point is in the polypltasic region of a ternary diagram, in tliis case Winsor ype. and thus R value can be deduced from the phase behavior observation. It is found that 1-3%. surfactant and equal proportions of oil and water is a fairly good choice in most systems In ionic systems a very low percentage of alcohol i.s often added to avoid the formation of mesophases. If the formulation should not be altered by the alcohol a good choice is rer-butanol. 

An industrial example of the use of chloroaluminate ionic liquids in aUcene catalysts is the recent development of the IFF Difasol process which is widely used industrially for aUcene dimerization (typically propene and butanes). It was observed by Chauvin and coworkers that chloroaluminate(III) ionic liquids would be good solvents for the nickel catalyst used in the reaction, and discovered that by using a ternary ionic liquid system ([C4-mim]Cl-AlCl3-EtAlCl2) it was possible to form the active catalyst Irom aNiCl2L2 precursor and that, the ionic liquid solvent stabilized the active nickel species. 

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