Phase equilibria in the Na,K||SO<Subscript>4</Subscript>,CO<Subscript>3</Subscript>,HCO<Subscript>3</Subscript>-H<Subscript>2</Subscript>O system at 25°C

Phase equilibria in the system Na,K|SO₄,CO₃,HCO₃-H₂O at 25°C are studied by the translation method. Thirty two double-saturation fields, 36 triple-saturation monovariant curves, and 13 quadruple-saturation points are distinguished in the system. The first closed phase diagram (phase complex) of the title system is designed.     

Phase equilibria in the Na,K‖CO<Subscript>3</Subscript>,HCO<Subscript>3</Subscript>,F-H<Subscript>2</Subscript>O system at 25°C

Phase equilibria in the Na,K‖CO₃,HCO₃,F-H₂O system at 25°C are studied by the translation method. Twenty nine double-saturation divariant fields, 31 triple-saturation monovariant curves, and 11 quadruple-saturation points for equilibrium solid phases are distinguished in the system. The first looped phase diagram (phase complex) of the title system is designed.     

Solubility in the Na,Ca∥CO<Subscript>3</Subscript>,HCO<Subscript>3</Subscript>–H<Subscript>2</Subscript>O system at 25°C

Solubility in the Na,Ca∥CO₃,HCO₃–H₂O system is studied; its phase diagram at 25°C is plotted.     

Solubility in the Na,Са||SO<Subscript>4</Subscript>,СО<Subscript>3</Subscript>–H<Subscript>2</Subscript>O system at 25°С

Solubility at the invariant points of the Na,Са||SO₄,СО₃–H₂O system at 25°C was studied, and a solubility diagram at this temperature constructed.     

Phase equilibria in the Na,K,Mg,Ca‖SO4,Cl-H2O system at 50°C in the astrakhanite crystallization region

Phase equilibria of the Na,K,Mg,Ca‖SO₄,Cl-H₂O system at 50°C in the astrakhanite (Na₂SO₄ · MgSO₄ · 4H₂O) crystallization region were studied using the translation method. Astrakhanite was found to be involved, as an equilibrium phase of the title system, in 35 divariant fields, 39 monovariant curves, and 22 invariant points. The data gained were used to construct a fragment of a schematic equilibrium phase diagram of the title system in the astrakhanite crystallization region.     

Phase Equilibria in the K,Cа∥SO<Subscript>4</Subscript>,CO<Subscript>3</Subscript>,HCO<Subscript>3</Subscript>–H<Subscript>2</Subscript>O System at 25°С

Phase equilibria in the system K,Cа∥SO₄,CO₃,HCO₃–H₂O have been studied at 25°С. This system at 25°С involves 7 invariant points, 21 monovariant curves, and 22 divariant fields. The data gained served to plot the first phase diagram (phase complex) of the studied system at 25°С.     

Solubility in the Na,СаǁSO<Subscript>4</Subscript>,СО<Subscript>3</Subscript>–H<Subscript>2</Subscript>O system at 0°С

Solubility at the invariant points of the Na,Са∥SO₄,СО₃–H₂O system at 0°C was studied, and a solubility diagram at this temperature constructed.     

Phase equilibria in the Na,K,Mg,Ca‖SO4,Cl-H2O system at 50°C in the halite crystallization field

Phase equilibria of the Na,K,Mg,Ca‖SO₄,Cl-H₂O system at 50°C in the halite (NaCl) crystallization field were studied using the translation method. Halite, which is an equilibrium phase of the title system at 50°C, was found to be involved in 25 invariant points, 59 monovariant curves, and 43 divariant fields. A fragment of the equilibrium phase diagram of the title system in the halite crystallization field was constructed.     

Phase equilibria in the Na,K,Mg,Ca‖SO4,Cl-H2O system at 50°C in the anhydrite crystallization region

Phase equilibria at invariant points of the Na,K,Mg,Ca‖SO₄,Cl-H₂O system at 50°C in the anhydrite (CaSO₄) crystallization region were studied. Anhydrite as an equilibrium phase at the six-component level is involved in formation of 22 invariant points, 58 monovariant curves, and 49 divariant fields. A fragment of an equilibrium phase diagram of the title system was constructed in the anhydrite crystallization region at 50°C.     

Four-component reciprocal system Na,K∥F,CO<Subscript>3</Subscript>, WO<Subscript>4</Subscript>

The four-component reciprocal system Na,K∥F, CO₃, WO₄ has been studied using differential thermal analysis in combination with projective and differential geometry. The a priori prediction of the crystallization path (CP) shows six quaternary invariant points; of them, three are eutectics and the others are peritectics. The dominant exchange and complexing reactions have been recognized. The following four-component systems have been studied: (NaF)₂-(KF)₂-K₂CO₃-K₃FWO₄ (1), (NaF)₂-K₂CO₃-K₂WO₄-K₃FWO₄ (2), (NaF)₂-Na₂CO₃-Na₂WO₄-K₂WO₄ (3),, and (NaF)₂-Na₂CO₃-K₂CO₃-K₂WO₄ (4); the coordinates of all quaternary invariant points have been determined.     

Phase equilibria in system LiCl–NaCl–H<Subscript>2</Subscript>O at 308 and 348 K

The solubilities and densities of the solutions in the ternary system LiCl–NaCl–H₂O at 308 and 348 K were determined by the method of isothermal dissolution equilibrium. There are one invariant point, two univariant isotherm dissolution curves, and two crystallization regions corresponding to monohydrate (LiCl · H₂O) and NaCl, respectively. This system at both temperatures belongs to hydrate type I, and neither double salt nor solid solution was found. A comparison of the phase diagram for the ternary system at 273–348 K shows that the area of crystallization region of LiCl · H₂O is decreased with the increasing of temperature, while that of NaCl is increased obviously. The solution density of the ternary system at two temperatures changes regularly with the increasing of LiCl concentration.     

Phase equilibria in the NaCl–KI–K<Subscript>2</Subscript>CrO<Subscript>4</Subscript> stable triangle of the Na,K‖Cl,I,CrO<Subscript>4</Subscript> system

The NaCl–KI–K₂CrO₄ stable triangle was studied by differential thermal analysis. The melting temperature, melt composition, and specific melting enthalpy corresponding to the ternary eutectic were determined in the system. The compositions of crystallizing phases in the eutectic were confirmed by X-ray diffraction.     

Phase equilibria in the ZnGeAs<Subscript>2</Subscript>–MnAs system

The ZnGeAs₂–MnAs system is a eutectic-type system as determined by X-ray powder diffraction, DTA, and microstructure observation, with the eutectic coordinates: 61 mol % ZnGeAs₂ mol %, 39 mol % MnAs, and T_m = 816°C. The eutectic is a lamellar eutectic as shown by microstructure examination. A characteristic feature of the system is a small mutual solubility of the components. Precision analysis of diffraction patterns enabled us to refine unit cell parameters for cubic and tetragonal ZnGeAs₂ phases. MnAs in alloys is shown to consist of a hexagonal phase and a orthorhombic phase. ZnGeAs₂ and MnAs alloys are ferromagnets (T_C ~ 320 K). Their magnetization increases in response to increasing MnAs content.     

Phase equilibria in the BaS–Ga<Subscript>2</Subscript>S<Subscript>3</Subscript> system

In the BaS–Ga₂S₃ system, the following compounds form: congruently melting compound BaGa₄S₇ (rhombic system, space group Pmn2₁, a = 1.477 nm, b = 0.624 nm, c = 0.593 nm, and T_melt = 1490 K) and incongruently melting compounds BaGa₂S₄ (cubic system, space group Pa3, a = 1.2661 nm, and Tmelt = 1370 K), Ba₂Ga₂S₅ (monoclinic system, space group C2/c, a = 1.529, b = 1.479, c = 0.858 nm, ß = 106.04°, and T_melt = 1150 K), Ba₃Ga₂S₆ (monoclinic system, space group C2/c, a = 0.909 nm, b = 1.448 nm, c = 0.903 nm, ß = 91.81°, and T_melt = 1190 K), Ba₄Ga₂S₇ (monoclinic system, space group P2₁/m, a = 1.177 nm, b = 0.716 nm, c = 0.903 nm, ß = 108.32°, and T_melt = 1230 K), and Ba₅Ga₂S₈ (rhombic system, space group Cmca, a = 2.249 nm, b = 1.215 nm, c = 1.189 nm, and T_melt = 1480 K). The compositions of eutectics are 38 and 72 mol % Ga₂S₃, and their melting points are 1120 and 1160 K, respectively. The BaS solubility in γ-Ga₂S₃ at 1070 K reaches 3 mol %.     

Phase equilibria in the MgS–In<Subscript>2</Subscript>S<Subscript>3</Subscript> system

Phase equilibria in the MgS–In₂S₃ system were studied. This system is of the dystectic type with a limited region of a solid solution based on β-In₂S₃. In the MgS–In₂S₃ system, a compound of the composition MgIn₂S₄ forms, which forms congruently at 1180 K and crystallizes in the cubic system (space group Fd3m) with the unit cell parameter a = 1.0689 nm. Eutectics have the compositions 47 and 62 mol % In₂S₃ and the melting points 1150 and 1120 K, respectively. The MgS solubility in β-In₂S₃ at 1070 K reaches 9 mol % MgS.     

Interaction of components in the NaOH-TiO<Subscript>2</Subscript> · H<Subscript>2</Subscript>O-H<Subscript>2</Subscript>O system at 25°C

Solubilities in the NaOH-TiO₂ · H₂O-H₂O system at 25°C were studied. The solubility isotherm was found to have two maxima. The formation of two compounds, Na₂Ti₅O₁₁ · 10H₂O and Na₂Ti₃O₇ · 7H₂O, was established.     

Physicochemical Analysis of the System Zr(SO<Subscript>4</Subscript>)<Subscript>2</Subscript>–Na<Subscript>2</Subscript>SO<Subscript>4</Subscript>–H<Subscript>2</Subscript>SO<Subscript>4</Subscript>–H<Subscript>2</Subscript>O at 25°С

The solubility in the quaternary water–salt system Zr(SO₄)₂ · 4Н₂О–Na₂SO₄–H₂SO₄–H₂O at 25°C was studied. It was found that, in the system, there is crystallization of not only Na₂SO₄ and Zr(SO₄)₄ · 4H₂O, but also sodium sulfate zirconates Na₂Zr(SO₄)₂(OH)₂ · 0.3H₂O, Na₄Zr(SO₄)₄ · 3H₂O, and Na₂Zr(SO₄)₂ · 3H₂O and two new compounds, S₁ and S₂, which are presumably Na₂ZrO(SO₄)₂ · 2H₂O and Na₂Zr₂O₂(SO₄)₃ · 6H₂O.     

Phase and extraction equilibria in H<Subscript>2</Subscript>O–sulfonol–HCl (H<Subscript>2</Subscript>SO<Subscript>4</Subscript>) and H<Subscript>2</Subscript>O–sodium dodecyl sulfate–HCl (H<Subscript>2</Subscript>SO<Subscript>4</Subscript>) systems

Solubility isotherms of water–sulfonol–hydrochloric (or sulfuric) acid and water–sodium dodecyl sulfate–hydrochloric acid systems at 75°C and a water–sodium dodecyl sulfate–sulfuric acid system at 50°C are constructed. Regions of two-phase liquid equilibrium suitable for use in extraction are found. Concentration parameters for extraction are determined. The interfacial distribution of a series of metal ions with and without such additional complexing reagents as diantipyrylmethane and diantipyrylheptane is studied.     

Phase equilibria and critical phenomena in the Li<Subscript>2</Subscript>SO<Subscript>4</Subscript>-K<Subscript>2</Subscript>SO<Subscript>4</Subscript>-H<Subscript>2</Subscript>O system at 380-400°C: Specifics of ternary phase diagrams with type 2 (p-Q) boundary subsystems

Phase equilibria in Li₂SO₄-KLiSO₄-H₂O and K₂SO₄-KLiSO₄-H₂O ternary systems, which contain type 2 salts (Li₂SO₄, KLiSO₄, and K₂SO₄), were studied at temperature of 380 to 400°C and pressures up to 90 MPa. Homogeneous supercritical (SC) fluids, which propagate from type 2 water-salt subsystems into a three-component region, change to heterogeneous liquid-phase equilibria as a result of the transformation of metastable immiscibility regions into stable equilibria. The heterogenization of SC fluids starts with critical phenomena in saturated solutions. In the K₂SO₄-KLiSO₄-H₂O system, the monovariant critical curve (l₁ = l₂ - s_KLiSO4 )(l_1 = l_2 - s_{KLiSO_4 } ) reveals a temperature maximum at the invariant double critical end point (DCE).     

Phase equilibria in the PbBi<Subscript>2</Subscript>S<Subscript>4</Subscript>–PbSnS<Subscript>2</Subscript> system

The PbBi₂S₄–PbSnS₂ system was studied by physicochemical analysis methods, and its state diagram was constructed. The system is partially quasi-binary; regions of solid solutions based on PbSnS₂ are determined. At a ratio between the initial components of 1: 1, congruently melting compound Pb₂SnBi₂S₆ forms. The unit cells parameters of Pb₂SnBi₂S₆ crystallizing in the orthorhombic system are: a = 15.60 Å, b = 7.80 Å, c = 4.26 Å; space group Pbmm.