Quaternary reciprocal systems

The system LiF-NaF-K2NbF7 is the planar section of the quaternary reciprocal system Li +, Na +, K + // F , [NbF7] . Both boundary binary systems LiF-K2NbF7 and... 

Quaternary reciprocal systems are composed of six components, which form three ternary reciprocal systems and two ternary systems with a common ion. The concentration diagram of this system can be represented by a three-sided prism, on each side is the vertical... 

Phase diagrams of quaternary reciprocal systems are represented in the literature only in the form of the unfolded surface of a three-sided prism. Such presentation of the phase diagram of the quaternary reciprocal system A+, B+, // X , Y is shown in... 

Figure 3.41. Phase diagram of the quaternary reciprocal system A" ", B+, C + // X, Y with the formation of two congruently and one incongruently melting compound.

Nitrates. Thermodynamic parameters (AH=114kJmor AS = 62 J moF K ) for reaction (16) in NaNOs-KNOa eutectic melt have been determined (500— 700 K). Corresponding data (AH = 95 kJ moF AS = 84 J moF K ) for reaction (17) have also been calculated. Physicochemical analyses have been carried out on NaNOa-KNOs, Ca(N0a)2-Sr(N03)2, Sr(NOa)2-Ba(NOa)2" binary systems (generally as part of a quaternary reciprocal system), and LiNOa-RbNOa-CsNOa and LiN0a-KN03-Sr(N0a)2 ternary systems. 

Ternary additive systems with common anion and quaternary reciprocal systems... 

Ca, K, Li, Na //NO3 with a minimum melting temperature of 109 °C [34], Recently, Bradshaw et al. published data on the quaternary reciprocal system K, Li, Na // NO2, NO3 with a minimum melting temperature of about 75 °C with the composition 33.5 mol% Li+, 47.9 mol% K" ", 18.6mol% Na" ", and a nitrate/nitriteratio of 0.56 [33]. Our own work presented in this paper focuses on the phase diagram determination of the latter system and stability measurements of different single salts and salt mixtures. 

This paper presents an overview of relevant alkali nitrate and nitrite salt mixtures for TES technology in the field of CSP. This overview includes well-known salt systems in the field (KN03-NaN03, KN03-NaN02-NaN03 - Hitec), as well as a recently published system with a low liquidus temperature. This system is based on the quaternary reciprocal systems K, Li, Na//N02, NO3. Compositions with a liquidus temperature as low as 72 °C have been reported. A phase diagram with a fixed ratio N03 /N02 = 0.5 has also been published. The stability of this mixture in air at 450 °C over 120 days is reported to be poor [33]. 

Quaternary additive system with common anion and quinary reciprocal system... 

Figure 4.30. Isothermal representation of a quaternary system of the reciprocal salt paif type a) square-based pyramid b) square prism...

The square-prism space model Figure 4.30b) illustrates another way in which a quaternary system of the reciprocal salt pair type may be represented. The vertical axis stands for the water content, and the points on the diagram are the same as those marked on Figure 4.30a. In both diagrams all surfaces formed between the internal curves represent solutions of three salts in water saturated with one salt, all internal curves solutions of three salts in water saturated with two salts, and the two points P and Q solutions of three salts in water saturated with the three salts. The section above the internal curved surfaces denotes unsaturated solutions, the section below them mixtures of liquid and solid. 

An example of a DNA network with multiple catalytic routes was studied by Achilles and von Kiedrowski. They analyzed a seff-repUcating system starting from three building blocks, which could form a five different member network with six catalytic pathways. Another example was presented by Sievers and von Kiedrowski, who studied a quaternary system of hexadeoxynucleotide analogs. They demonstrated that cross-catalytic replication can be observed in template-directed reaction systems if the reciprocal template effects are similar in efficiency and if the reaction system is not dominated by autocatalytic syntheses of self-complementary products, which occur as parallel reactions. 

Table 5. Physicochemical properties of the metastable reciprocal quaternary system (NaCl- KCl - Na2B407 - K2B4O7 - H2O) at 308.15 K...

A comparison of the dry-salt diagrams of the metastable phase equilibrium at 308.15 K and the stable phase equilibrium at 298.15 K for the same system is shown in Figure 8. The metastable crystallization regions of borax and potassium chloride are both enlarged while the crystallized area of other minerals existed is decreased. When compared with the stable system, the solubility of borax in water in the metastable system is increased from 3.13 % to 5.70 %. The metastable phenomenon of borax is obvious in this reciprocal quaternary system. 

On the basis of the calculated solubilities, a comparison diagram among model I, model II, experimental values for the reciprocal quaternary system at 298.15 K are shown in Figure 9. 

Deng, T.L. Meng, L.Z. Sim, B. (2008d). Metastable phase equilibria of the reciprocal quaternary system containing sodium, potassium, chloride and borate ions at 308.15 K, J. Chem. Eng. Data, Vol. 53, No. 3, pp. 704-709, ISSN 0021-9568... 

A special case of great industrial relevance is the examination of reciprocal salt pairs representing a quaternary system of two salts that do not share a common ion... 

Figure 3.6 Representation of a quaternary system in the phase diagram, (a) Three-dimensional representation of a quaternary system A, B, C, and D in the quadrangular prism (square prism base). The four vertical faces of the prism correspond to the four binary systems, A/B, B/C, C/D, and A/D. (b) Square diagram representing the reciprocal salt pairs...

As already introduced in Section 3.1.4, the reciprocal salt pairs represent industrially relevant examples of quaternary systems. They play an important role in the production of inorganic salts via the so-called redprocal conversion in water. Industrial apphcations are the manufacture of K2SO4 and Na2C03 on the basis of mined potash ores according to the following readions ... 

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