Quaternary Reciprocal System Research Articles

Functional borates and their high-pressure polymorphic modifications. Review

The article presents the results of many years of studies of the growth of a low-temperature modification of barium borate b-BaB2O4 (R3с) crystals in the Na, Ba, B // O, F quaternary reciprocal system. Barium borate b-BaB2O4 is the most important nonlinear optical crystal of the UV spectrum. The key factor determining the quality of crystals is the choice of an optimal solvent. The article presents phase diagrams and the results of the growth of b-BaB2O4 crystals in several subsystems of the studied quaternary reciprocal system. Using atomistic modeling, we predicted and then experimentally obtained new high-pressure modifications: g-BaB2O4 (P21/n), whose structure includes edge-sharing tetrahedra, and d-BaB2O4 with assumed symmetry Pa3. In our study, we also focused on a solid solution with an “antizeolite” structure, which also crystallizes in the Na, Ba, B // O, F system.

Phase complex modeling and experimental identification of the compositions of low-melting electrolyte mixtures in the stable triangle LiF-NaF-KCl of the quaternary reciprocal system Li+,Na+,K+||F−,Cl−

Phase complex modeling and experimental identification of the compositions of low-melting electrolyte mixtures in the stable triangle LiF-NaF-KCl of the quaternary reciprocal system Li+,Na+,K+||F−,Cl−

Описание и исследование химического взаимодействия в системе Li+,Na+||F-,Cl-,Вг

The use of melts in various fields of industry and scientific research is based on the study of the properties of melts and the chemical processes occurring in them. In modern engineering and technology, a significant number of processes are associated with the use of mixtures of lithium and sodium halides as mixtures that accumulate heat, as electrolytes for medium-temperature chemical current sources. Therefore, the interest in the study of systems involving such systems is continuously increasing. The paper calculates the thermal effects of exchange reactions and Gibbs energy in ternary reciprocal systems of a quaternary reciprocal system Li+,Na+||F-,Cl-,Br-, as well as for a mixture corresponding to the central point of the conversion line. The conversion line is obtained as a result of the intersection of unstable and stable triangles. In accordance with the calculation data, it is shown that the conversion lines in the skeleton of the compositions intersect at the conversion point K3 with the maximum thermal effect of the reaction equal to the sum of the thermal effects of the reactions (as well as the Gibbs energies) for mixtures corresponding to the conversion points K1 and K2.To confirm the stability of the LiF-NaCl-NaBr triangle linking the stable tetrahedron LiF-NaCl-NaBr-NaF and the stable pentatope LiF-LiCl-LiBr-NaCl-NaBr, the interaction of the initial powder mixture of 50 mol % NaF+25 mol.% LiCl+25 mol.% LiBr has been studied by thermogravimetry. The phase transition temperatures are assigned to the heating curve of the mixture. When heated at a rate of 20 K/min, the exothermic effect begins at 463 oC and ends at 504 оC. For a stable triangle, a melt crystallization scheme of the composition of the central point of the conversion line is shown. Stable crystallizing phases have been confirmed by X-ray phase analysis.

Topological Isomorphism of Liquid–Vapor, Fusibility, and Solubility Diagrams: Analogues of Gibbs–Konovalov and Gibbs–Roozeboom Laws for Solubility Diagrams

The comprehensive topological isomorphism of liquid–vapor, fusibility, and solubility diagrams in the proper sets of variables is proven with the aid of van der Waals equations of the shift in phase equilibrium. Analogues of Gibbs–Konovalov and Gibbs–Roozeboom laws are demonstrated in solubility diagrams of ternary and quaternary systems under crystallization of different types of solid solutions. For the demonstration, the quaternary reciprocal system K+,NH4+||Cl−,Br−−H2O and its ternary subsystems with modeling of the liquid phase within the framework of the classical Pitzer formalism are mainly used. An algorithm for calculating solubility equilibria in these systems is given.

Modeling of the Phase Assemblage of the LiF–Li2CrO4–LiRbCrO4–LiKCrO4 Stable Tetrahedron of the Li+, K+, Rb+||F–, Quaternary Reciprocal System

Here, phase equilibria in a quaternary reciprocal system comprised of fluorides and chromates of lithium, potassium, and rubidium was studied. The phase assemblage of the system was partitioned to stable simplices. The Li–Li2CrO4–LiRbCrO4–LiKCrO4 stable tetrahedron was selected as the subject matter of this study due to its undoubted scientific importance. The analysis of the boundary elements predicted, and the DTA experimental study of phase equilibria in the system proved, that monovariant phase equilibrium L ⇄ LiF + α-Li2CrO4 + (LiKxRb1 – xCrO4)ss is realized in the system, described by line Е 397–Е 400; the characteristics of the minimum point of this monovariant equilibrium (Min◻ 367) were elucidated. The mass balance of the phase reaction for this point is presented. A 3D model of the phase assemblage of the system was designed based on experimental data. The system preserves the continuity of (LiKxRb1 – xCrO4)ss solid solutions. The mixture whose composition corresponds to point Min◻ 367 has a relatively low melting temperature and can serve as a material for new fusible electrolytes in chemical current sources; it can also be of interest as an electrolytic bath for recovery of metals from melts.

Comparative characteristics of various solvents of the Na, Ba, B//O, F system for the growth of β-BaB2O4 crystals and PT-diagram of BaB2O4 polymorphs

Nonlinear optical β-BaB2O4 (BBO) crystals have been grown in six different systems belonging to the Na, Ba, B//O, F quaternary reciprocal system: I BaB2O4–BaF2, II BaB2O4–(NaF)2, III BaB2O4–Ba2Na3[B3O6]2F, IV BaB2O4–NaBO2, V BaB2O4–NaBaBO3, and VI BaB2O4–NaBaBO3–Ba2Na3[B3O6]2F. Comparative characteristics of the systems and grown crystals are given. The best results in terms of crystal quality have been achieved in systems V and VI. The observed occurrence of scattering centers in β-BaB2O4 crystals might be associated with the sodium concentration in the initial high-temperature solution, and, as a consequence, with the sodium concentration in the β-BaB2O4 crystal. The PT-diagram and electronic properties of BaB2O4 polymorphs were studied using the first-principles calculations.

Phase Equilibrium of the Quaternary System LiBr-Li2SO4-KBr-K2SO4-H2O at 308.15 K

The phase equilibria of the reciprocal quaternary system LiBr-Li2SO4-KBr-K2SO4-H2O and its ternary sub-systems LiBr-Li2SO4-H2O and KBr-K2SO4-H2O at 308.15 K were studied using the isothermal dissolution equilibrium method. Then, the solubility data of the equilibrium solutions were collected, and the phase diagrams were plotted. The phase diagrams of the ternary sub-systems at 308.15 K were compared with those at other temperatures. This study found that the phase diagram of the LiBr-Li2SO4-H2O system at 308.15 K consisted of an invariant point, two solid-phase crystallization regions of Li2SO4·H2O and LiBr·2H2O, and their corresponding solubility curves. The system generated two hydrated salts, which belonged to the hydrate type I phase diagram. The phase diagram of the KBr-K2SO4-H2O system at 308.15 K consisted of an invariant point, two univariant solubility curves, and two solid-phase crystallization regions of KBr and K2SO4, and no solid solution and double salts were formed. Thus, it belonged to a simple co-saturation type phase diagram. In the LiBr-Li2SO4-KBr-K2SO4-H2O system, K2SO4·Li2SO4 double salt formed at 308.15 K, and the phase diagram consisted of three invariant points, five crystallization regions, and seven univariant solubility curves.

Thermodynamics of Ba(NO3)2(aq) to 393 K and solubilities in the reciprocal system Na+–Ba2+–Cl−–NO3−−H2O with implications for salt damage

This paper reports on an ion interaction (Pitzer) model for the calculation of solution properties and phase equilibria in the binary system Ba(NO3)2–H2O valid in the temperature range (273–393) K. The interaction parameters were determined after critical assessment of available thermodynamic data of the system. In addition, the model parameters for the calculation of solubilities and activities in the quaternary reciprocal system Na+–Ba2+–Cl−–NO3−–H2O at near ambient temperatures are provided. New ternary interaction parameters are reported for the Na+–Ba2+–NO3−–H2O, Na+–Ba2+–Cl––H2O and Ba2+–Cl−–NO3−–H2O systems. Predicted solubility diagrams in the full reciprocal quaternary systems are compared to available experimental data yielding good agreement. Finally, the impact of additional ions on the solubility and deliquescence behavior of Ba(NO3)2(cr) in terms of its contribution to crystallization damage processes in wall paintings and other porous materials is discussed.

Stable Phase Equilibria in Li + //Cl – , S $${\text{O}}_{4}^{{2 - }}$$ , B 4 $${\text{O}}_{7}^{{2 - }}$$ –H 2 O and Li + , Mg 2+ //Cl – , B 4 $${\text{O}}_{7}^{{2 - }}$$ –H 2 O Quaternary Systems at 273 K

The isothermal dissolution method was used to study the stable phase equilibria in the simple quaternary system Li+//Cl–, S $${\text{O}}_{4}^{{2 - }}$$ , B4 $${\text{O}}_{7}^{{2 - }}$$ –H2O and reciprocal quaternary system Li+, Mg2+//Cl–, B4 $${\text{O}}_{7}^{{2 - }}$$ –H2O at 273 K. The stable phase equilibrium of simple quaternary system Li+//Cl–, S $${\text{O}}_{4}^{{2 - }}$$ , B4 $${\text{O}}_{7}^{{2 - }}$$ –H2O belongs to hydrate type I, and there is no complex salt. The phase diagram is constituted of an invariant point, three univariant solubility curves, and three solid phase crystalline regions. The stable phase equilibrium of reciprocal quaternary system Li+, Mg2+//Cl–, B4 $${\text{O}}_{7}^{{2 - }}$$ –H2O belongs to complex type, and the double salt of lithium carnallite (LiCl·MgCl2·7H2O) is found. There are three invariant points, seven univariant solubility curves, and five solid phase crystalline regions.

Phase equilibria of the reciprocal quaternary system (Li+, NH4+//Cl−, SO42−-H2O) at 288.15 K

Based on the isothermal solution equilibrium method, a systematic study of the quaternary (Li+, NH4+//Cl−, SO42−-H2O) and its subsystems ((NH4)2SO4-NH4Cl-H2O, NH4Cl-LiCl-H2O and (NH4)2SO4-Li2SO4-H2O) at 288.15 K were undertaken. The phase diagrams of these systems were drawn by the experimental solubility data. The ternary system (NH4)2SO4-NH4Cl-H2O is a simple system at 288.15 K while solid solution (LiCl·2H2O)x(NH4Cl)1-x was formed in the ternary system NH4Cl-LiCl-H2O. The compound salt LiNH4SO4 and solid solution (Li2SO4·H2O)x(LiNH4SO4)1-x were produced in the system (NH4)2SO4-Li2SO4-H2O. The phase diagram of the quaternary system (Li+, NH4+//Cl−, SO42−-H2O) include seven solid phase crystallization regions (NH4Cl, LiCl·2H2O, (LiCl·2H2O)x(NH4Cl)1-x, Li2SO4·H2O, (NH4)2SO4, LiNH4SO4 and (Li2SO4·H2O)x(LiNH4SO4)1-x).

Stable Tetrahedron NaCl – KCl – PbCl2 – PbWO4 in the quaternary reciprocal system Na, K, Pb // Cl, WO4

The phase diagram of the stable tetrahedron NaCl – KCl – PbCl2 – PbWO4 of the quaternary reciprocal system Na, K, Pb // Cl, WO4 was first studied using methods of differential thermal analysis. Its phase diagram was triangulated and stable triangulating internal sections of NaCl – PbWO4 – KCl.2PbCl2, NaCl – PbWO4–2KCl. PbCl2 and obtained tetrahedra NaCl – PbCl2 – PbWO4 – KCl.2PbCl2, NaCl – KCl – PbWP4, and NaCl – KCl – PbWP4. There are coordinates of three quadruple invariant points revealed.

Partition of the Quaternary Reciprocal System Na,Rb||F,I,CrO4 and Investigation of the Stable Tetrahedron NaF–RbI–RbF–Rb2CrO4

The quaternary reciprocal system Na,Rb||F,I,CrO4 was studied, low-melting mixtures based on which are promising as fusible electrolytes for chemical current sources, heat-storage materials, and media for growing single crystals. The system was partitioned into simplexes using graph theory, and the tree of phases of the system was constructed. The tree of phases is linear and contains four stable tetrahedra sharing stable cutting triangles. The combined stable tetrahedron NaF–RbI–RbF–Rb2CrO4 was investigated by differential thermal analysis. The crystallization surface of this stable tetrahedron is represented by the volumes of sodium fluoride, rubidium iodide, rubidium fluoride, rubidium chromate, and the compound Rb3CrO4F. Monovariant equilibrium lines meet at two quaternary invariant points: eutectic E◻491 and peritectic P◻508.

Growth of β‐ΒaΒ2O4 Crystals from Solution in LiF–NaF Melt and Study of Phase Equilibria

AbstractPhase equilibria in the ΒaΒ2O4–LiF–NaF section of the quaternary reciprocal system Li, Na, Ba // BO2, F are studied by the solid‐phase synthesis, differential thermal analysis, and visual polythermal analysis techniques. It is shown that this system can be used for the growth of bulk β‐ΒaΒ2O4 crystals.

Stable Tetrahedron NaBO2–Na2CO3–Na2WO4–K2WO4of the Quaternary Reciprocal System Na,K∥BO2,CO3,WO4

By differential thermal analysis using the calculation-experimental method, the phase diagram of the quaternary system NaBO2–Na2CO3–Na2WO4–K2WO4 was studied, and the coordinates of ternary eutectics and two quaternary eutectics were determined: E 1 □ (530°C, 5.6% NaBO2, 30% Na2CO3, 55.3% Na2WO4, 9.1% K2WO4). It was shown that the calculated and experimental data on the coordinates of the quaternary eutectics agree satisfactory.

Partition of the Quaternary Reciprocal System Na,K∥Cl,I,CrO4 and Investigation of Its Stable Elements

Investigation of multicomponent salt systems is important in the context of the wide use of invariant mixtures as electrolytic media for separation of metals and heat-storage materials. In this work, the quaternary reciprocal system Na,K∥Cl,I,CrO4 was partitioned into simplexes using graph theory. The tree of phases of the system was constructed, and stable elements were determined. The stable tetrahedron NaCl–KCl–KI–K2CrO4 of the system Na,K∥Cl,I,CrO4 was studied by differential thermal analysis. In the stable tetrahedron, the melting point and composition (equiv. %) of a quaternary eutectic were found: (0.25% KCl, 42.40% NaCl, 30.92% KI, 26.43% K2CrO4; 451°C).

Differentiation of the Multicomponent System Na,K,Sr∥Cl,NO3: Phase Diagram and Physicochemical Properties of Salt Mixtures in the System NaNO3—NaCl—KNO3—Sr(NO3)2

The differentiation of the quaternary reciprocal system Na,K,Sr∥Cl,NO3 was performed based on graph theory using special software. Stable and metastable complexes of the system were found using a matrix of reciprocal pairs of salts. For the first time, by physicochemical analysis methods (differential thermal, visual polythermal, and X-ray powder diffraction analyses using the method of thermal analysis of successive projections of the composition polytope), the quaternary system NaNO3-NaCl-KNO3-Sr(NO3)2, which is a stable complex of the quaternary reciprocal system Li,Ca,Ba∥F,WO4, was studied and the coordinates of invariant points were determined. The density and electrical conductivity were determined, volumetric changes were calculated, and the corrosion of 12Kh18N10T steel in eutectic and peritectic salt mixtures was investigated.

Phase Equilibria of the Reciprocal Quaternary System (Na+, Ca2+//Cl–, Borate–H2O) at 288.15 K and 0.1 MPa

To exploit the valuable features of brine resources with high concentrations of borate ions, the solubility data and corresponding physicochemical properties (refractive index, density, viscosity, and pH) for the reciprocal quaternary system (Na+, Ca2+//Cl–, borate–H2O) at 288.15 K were determined experimentally using the method of isothermal dissolution equilibrium. The dry-salt and water-phase diagrams and the diagrams of physicochemical properties (refractive index, density, viscosity, and pH) against J(B4O72–) in the solution were established. In the dry-salt phase diagram of the quaternary system at 288.15 K, two invariant points, five univariant curves, and four crystallization regions corresponding to gowerite (CaB6O10·5H2O), borax (Na2B4O7·10H2O), antarcticite (CaCl2·6H2O), and sodium chloride (NaCl) were found. The area of crystallization region of CaB6O10·5H2O is larger than that of other coexisting salts, which indicates that the solubility of gowerite in this system is the lowest and that it i...

Metastable Phase Equilibrium in the Reciprocal Quaternary System LiCl+MgCl2+Li2SO4+MgSO4+H2O at 348.15 K and 0.1 MPa

The metastable solubilities and the physicochemical properties including density and pH of the reciprocal quaternary system(LiCl+MgCl2+Li2SO4+MgSO4+H2O) at 348.15 K and 0.1 MPa were determined using the isother-mal evaporation method. The dry-salt diagram and water-phase diagram were plotted based on the experimental data. There are five invariant points, eleven univariant curves, and seven crystallization zones corresponding to hexahy-drite, tetrahydrite, kieserite, bischofite, lithium sulfate monohydrate, lithium chloride monohydrate and lithium car-nallite. Comparison between the stable and metastable diagrams at 348.15 K indicates that the metastable phenome-non of magnesium sulfate is obvious, and the crystallization regions of hexahydrite and tetrahydrite disappear in the stable phase diagram. A comparison of the metastable dry-salt phase diagrams at 308.15, 323.15 and 348.15 K shows that with the increasing of temperature the epsomite crystallization zone disappears from the dry-salt phase diagram of 303.15 K, and a new kieserite crystallization zone is presented at 348.15 K. The density and pH in the metastable equilibrium solution present regular change with the increasing of Janecke index J(2Li+), and the calculated densities using the empirical equation agree well with the experimental values.

Stable Triangle LiF–NaF–CsI of the Quaternary Reciprocal System Li, Na, Cs∥F, I

The quaternary reciprocal system Li, Na, Cs∥F, I was partitioned into simplexes, and the tree of phases was constructed. By differential thermal analysis, the stable triangle LiF–NaF–CsI was studied, and the characteristics of a ternary eutectic were determined.

Solubility of the Copper(II) Salt–Sodium Formate–Water Systems at 25°C

Solubilities in the CuSO4 (CuCl2, Cu(NO3)2)–NaHCOO–H2O systems are studied at 25°C using the isothermal sections method. Crystallization regions of copper(II) formate mono- and dihydrate are elucidated. It is proved that copper(II) formate can be synthesized in CuAn2 + 2NaHCOO ⇆ Cu(HCOO)2 + 2NaAn–H2O quaternary reciprocal systems using the conversion method.