Stable tetrahedron LiF–KI–K<Subscript>2</Subscript>CrO<Subscript>4</Subscript>–Li<Subscript>2</Subscript>CrO<Subscript>4</Subscript> of the quaternary reciprocal system Li,K||F,I, CrO<Subscript>4</Subscript>

The stable tetrahedron LiF–KI–K₂CrO₄–Li₂CrO₄ of the quaternary reciprocal system Li, K||F, I, CrO₄ was experimentally studied by differential thermal analysis. The compositions and melting points of mixtures of components at two eutectic points were determined. Based on experimental data, a T–x–y–z model of the phase complex was constructed, which allows one to solve problems of building polythermal and isothermal sections. A method for constructing the diagram of material balance of equilibrium phases for a given composition was developed. The diagram enables one to find the ratio between the amounts of the liquid and solid phases at constant temperature and also monitor the change in the composition of the phases within a chosen temperature range.     

Ternary Systems LiBr–LiVO<Subscript>3</Subscript>–Li<Subscript>2</Subscript>CrO<Subscript>4</Subscript> and KBr–KVO<Subscript>3</Subscript>–K<Subscript>2</Subscript>CrO<Subscript>4</Subscript>

The binary system KVO₃–K₂CrO₄ and two ternary systems, LiBr–LiVO₃–Li₂CrO₄ and KBr–KVO₃–K₂CrO₄, were studied. In the ternary systems, the compositions and melting points of eutectic alloys were determined by differential thermal analysis: (49.0 mol % LiBr, 5.0 mol % LiVO₃, 46.0 mol % Li₂CrO₄, 400°C) and (17.0 mol % KBr, 78.0 mol % KVO₃, 5.0 mol % K₂CrO₄, 458°C), respectively.     

Ternary Systems NaHal–NaVO<Subscript>3</Subscript>–Na<Subscript>2</Subscript>CrO<Subscript>4</Subscript> (Hal = Cl,Br)

Phase equilibria in the ternary systems NaHal–NaVO₃–Na₂CrO₄ (Hal = Cl, Br) were studied. By differential thermal analysis, eutectic alloys were found at points with coordinates (14.0 mol % NaCl, 66.5 mol % NaVO3, 19.5 mol % Na₂CrO₄, 530°C) and (27.0 mol % NaBr, 47.5 mol % NaVO₃, 25.5 mol % Na₂CrO₄, 499°C). By differential scanning calorimetry, the specific enthalpies of melting of the eutectics were determined. X-ray powder diffraction analysis of the eutectic alloy in the system NaBr–NaVO₃–Na₂CrO₄ was made.     

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 System LiF–KI–KF–K<Subscript>2</Subscript>CrO<Subscript>4</Subscript>

Phase equilibria were experimentally studied in the system LiF–KI–KF–K₂CrO₄, which is the stable tetrahedron of the quaternary reciprocal system Li, K∥F, I, CrO₄. Differential thermal analysis revealed the compositions and transformation temperatures at the eutectic point E^□ 488 (L ? LiF + KF + KI + α-K₂CrO₄) and the peritectic point P^□ 510 (L + K₃FCrO₄ ? KI + α-K₂CrO₄ + KF). A computer model of the phase complex of the system was built, which can predict phase transformations at an arbitrary composition in the system. Isothermal sections of the systems were constructed, using which the phase composition at the temperature of the section can be calculated.     

Phase equilibria in the stable tetrahedron LiF–LiBr–Li<Subscript>2</Subscript>CrO<Subscript>4</Subscript>–KBr of the quaternary reciprocal system Li,KǁF,Br,CrO<Subscript>4</Subscript>

Phase equilibria in the stable tetrahedron LiF–LiBr–Li₂CrO₄–KBr of the quaternary reciprocal system Li,K∥F,Br,CrO₄ were studied by differential thermal analysis. The composition (equiv %) and melting point of a quaternary eutectic were found as (2% LiF, 60% LiBr, 3% Li₂CrO₄, 35% KBr, 315°C).     

Multicomponent systems LiCl–LiBr–Li<Subscript>2</Subscript>SO<Subscript>4</Subscript> and LiCl–LiBr–Li<Subscript>2</Subscript>SO<Subscript>4</Subscript>–Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript>

Phase equilibria in the LiCl–LiBr–Li₂SO₄ ternary system and the LiCl–LiBr–Li₂SO₄–Li₂MoO₄ quaternary system were studied by differential thermal analysis. The compositions and temperatures of minima in the ternary and quaternary systems were determined to be (31.2 mol % LiCl, 46.8 mol % LiBr, 22.0 mol % Li₂SO₄, 460°C) and (25.2 mol % LiCl, 30.2 mol % LiBr, 14.6 mol % Li₂SO₄, 30.0 mol % Li₂MoO₄, 411°C), respectively.     

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.     

Synthesis of nanopowders and physicochemical properties of ceramic matrices of the LaPO<Subscript>4</Subscript>–YPO<Subscript>4</Subscript>–(H<Subscript>2</Subscript>O) and LaPO<Subscript>4</Subscript>–HoPO<Subscript>4</Subscript>–(H<Subscript>2</Subscript>O) systems

Sol-gel method was used to synthesize nanosize powders in the LaPO₄–YPO₄–(H₂O) and LaPO₄–HoPO₄–(H₂O) systems. Dense ceramic samples with high microhardness (up to 25 GPa) were formed from these powders by sintering at temperatures of up to 1600°C. The isomorphic capacity of the monoclinic LaPO₄ matrix for the second component (yttrium or holmium) simulating radioactive nuclides of the actinide-rare-earth fraction was found to be high. The composites are stable in aqueous solutions, which is indicated by the low concentration of lanthanum and yttrium ions during leaching test (~10^–7 g L^–1). The results obtained in the study can be used to develop new high-efficiency ceramic matrices for solidification of the actinide-rare-earth fraction of liquid wastes formed in processing of the spent nuclear fuel.     

Phase formation in the system Li<Subscript>2</Subscript>MoO<Subscript>4</Subscript>–MgMoO<Subscript>4</Subscript>–Sc<Subscript>2</Subscript>(MoO<Subscript>4</Subscript>)<Subscript>3</Subscript>

Phase formation in the system Li₂MoO₄–MgMoO₄–Sc₂(MoO₄)₃ was studied by X-ray powder diffraction analysis and differential thermal analysis. Ternary molybdate LiMgSc(MoO₄)₃ was synthesized, which crystallizes in the triclinic system (space group P\(\bar 1\)). In the Li₂Mg₂(MoO₄)₃–Li₃Sc(MoO₄)₃ section, a continuous solid solution in the rhombic system was found to form (space group Pnma).     

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.     

Glass Formation in the Al<Subscript>2</Subscript>(SO<Subscript>4</Subscript>)<Subscript>3</Subscript>–(CH<Subscript>3</Subscript>)<Subscript>2</Subscript>SO–H<Subscript>2</Subscript>O System

The glass formation in the Al₂(SO₄)₃–(CH₃)₂SO–H₂O system was found for the first time. The competitive ability of ligands, dimethyl sulfoxide and water (which are strong donors), for entering the first coordination sphere of aluminum is considered. The possibility of mixed coordination of (CH₃)₂SO (via sulfur and oxygen atoms) in the first coordination sphere of aluminum with retention of the glass-forming ability of the sample was suggested on the basis of IR spectral study.     

Theoretical analysis of the system Li,K, Ca,Ba||F,WO<Subscript>4</Subscript>: Physicochemical properties of the system LiF–K<Subscript>2</Subscript>WO<Subscript>4</Subscript>–BaF<Subscript>2</Subscript>–CaF<Subscript>2</Subscript>–BaWO<Subscript>4</Subscript>

The differentiation of the quaternary reciprocal system Li, K, Ca, Ba||F, WO₄ was performed based on the 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 a set of physicochemical analysis methods (differential thermal, visual polythermal, and X-ray powder diffraction analyses), based on the method of thermal analysis of successive projections of the composition polytope, the quaternary system LiF–K₂WO₄–CaF₂–BaF₂–BaWO₄, which is a stable complex of the quaternary reciprocal system Li, K, Ca, Ba||F, WO₄, was studied and the coordinates of invariant points were determined.     

Crystal structure of Na<Subscript>3</Subscript>(NH<Subscript>4</Subscript>)<Subscript>2</Subscript>[Ir(SO<Subscript>3</Subscript>)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>]·4H<Subscript>2</Subscript>O

The complex Na₃(NH₄)₂[Ir(SO₃)₂Cl₄]·4H₂O was examined with single crystal X-ray diffraction and IR spectroscopy. Crystal data: a = 7.3144(4) Å, b = 10.0698(5) Å, c = 12.3748(6) Å, β = 106.203(1)°, V = 875.26(8) ų, space group P2₁/c, Z = 2, d _calc = 2.547 g/cm³. In the complex anion two trans SO ₃ ^2? groups are coordinated to iridium through the S atom. The splitting of O-H bending vibrations of crystallization water molecules and N-H ones of the ammonium cation is considered in the context of different types of interactions with the closest neighbors in the structure.     

System RbF–RbBr–Rb<Subscript>2</Subscript>SO<Subscript>4</Subscript>

The three-component system RbF–RbBr–Rb₂SO₄ has been studied by differential thermal analysis (DTA). The melting temperatures and compositions corresponding to a eutectic point and a peritectic point have been determined. Invariant, monovariant, and divariant equilibrium states are described.     

Crystal structure and thermal properties of [Au(en)<Subscript>2</Subscript>]<Subscript>2</Subscript>[Cu(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>]<Subscript>3</Subscript>·8H<Subscript>2</Subscript>O

The crystal structure of a double complex salt of the composition [Au(en)₂]₂[Cu(C₂O₄)₂]₃·8H₂O (en = ethylenediamine) at 150 K is determined by single crystal X-ray diffraction. The crystal data for C₂₀H₄₈Au₂Cu₃N₈O₃₂ are: a = 9.1761(3) Å, b = 16.9749(6) Å, c = 13.4475(5) Å, β = 104.333(1)°, V = 2029.43(12) ų, P2₁/c space group, Z = 2, d _x = 2.450 g/cm³. It is demonstrated that the thermal decomposition of the double complex salt in a helium or hydrogen atmosphere affords the solid solution Au_0.4Cu_0.6.     

Lanthanide-Organic Frameworks Based on {Ln<Subscript>4</Subscript>(μ<Subscript>3</Subscript>-OH)<Subscript>4</Subscript>(μ<Subscript>2</Subscript>-OH)<Subscript>2</Subscript>} Cluster Units

Abstract  

Three novel lanthanide-organic frameworks: [Ln₂(pyba)₃(μ₃-OH)₂(μ₂-OH)(H₂O)] _n (Ln = Er (1), Y (2), Dy (3) Hpyba = 4-pyridin-4-yl-benzoic acid) have been hydrothermally synthesized and structurally characterized by single crystal X-ray diffraction. Structure analysis shows that each {Ln₄(μ₃-OH)₄(μ₂-OH)₂} cluster units interconnect to form 1-D chains, which are further linked by π–π interactions to make a 3-D supramolecular network structure. Furthermore, the IR, PXRD and TGA of compounds 1–3 were also studied.     

Concentration Space of Homogeneous Garnet in the System Ga<Subscript>2</Subscript>O<Subscript>3</Subscript>–(Y,Bi)<Subscript>3</Subscript>(Fe,Ga)<Subscript>5</Subscript>O<Subscript>12</Subscript>–Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>

The concentration space of homogeneous garnet in the system Ga₂O₃–(Y, Bi)₃(Fe, Ga)₅O₁₂–Fe₂O₃ was determined by X-ray powder diffraction analysis. The obtained results expand the knowledge of the possible variations of cation ratios Y : Bi : Fe : Ga in garnet, which can be used for searching for and creating new stable magneto-optical materials.     

Crystal structure and vibrational spectra of M[VO<Subscript>2</Subscript>(SeO<Subscript>4</Subscript>)(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>]·H<Subscript>2</Subscript>O (M = K,Rb, NH<Subscript>4</Subscript>)

By the hydration of MVO(SeO₄)₂ with saturated water vapors at room temperature a series of isostructural complex compounds of vanadium(V) of the composition M[VO₂(SeO₄)(H₂O)₂]·H₂O (K, Rb, NH₄) are synthesized and their physicochemical properties are studied. Based on the X-ray and neutron diffraction data, it is found that their crystal structure is composed of VO₆ octahedra linked in infinite chains by bridging SeO₄ tetrahedra. Each of the VO₆ octahedra has two short terminal V-O bonds forming a bent dioxovanadium group VO₂⁺. Two water molecules are coordinated by vanadium and one molecule is out of the first coordination sphere in the interchain space. The vibrational spectra of the studied compounds are completely consistent with their structural features.     

Synthesis and structure of the [Co(NioxH)<Subscript>2</Subscript>(Thio)<Subscript>2</Subscript>]<Subscript>2</Subscript>SO<Subscript>4</Subscript>·2H<Subscript>2</Subscript>O complex compound

A new Co(III) complex of 1,2-cyclohexanedionedioxime and thiocarbamide with an SO ₄ ^2? anion and solvation water molecules in the outer sphere has been synthesized and its structure has been defined. Orthorhombic crystals, a = 11.659(2) Å, b = 26.448(5) Å, c = 30.142(6) Å, V = 9295(3) Å ³, Z = 8, d_calc = 1.599 g/cm³, space group Pbca; final R index is 0.0578 for 8221 reflections with I > 2σ(I). In the octahedral Co(III) complex, two 1,2-cyclohexanedionedioxime residues lie in the equatorial plane, while two thiocarbamide molecules are in the axial plane. Intramolecular bonds: N-H…O and O-H…O type hydrogen bonds and π-π interactions that stabilize the complex cations. In crystal, the components are linked by N-H…O and O-H…O hydrogen bonds into a 3D framework.