TeO<Subscript>2</Subscript>–(NaPO<Subscript>3</Subscript>)<Subscript>6</Subscript> Glass-Forming System

It is suggested to use sodium hexametaphosphate as a new glass-forming agent for tellurite glasses. The limits of the glass-forming region were determined for the TeO₂–(NaPO₃)₆ system, and a selective study of the thermal behavior of the glasses synthesized was carried out by the method differential scanning calorimetry. The optical transmission in the UV, visible, and IR spectral ranges was examined. It was shown that oxides of rare-earth elements can be introduced into the glass, which opens up prospects for application of the system as a matrix for generation of laser light in the 2-μm range, required in fabrication of medical lasers.     

High-temperature reactions in the Co<Subscript>3</Subscript>Cr<Subscript>4</Subscript>(PO<Subscript>4</Subscript>)<Subscript>6</Subscript>–Cr(PO<Subscript>3</Subscript>)<Subscript>3</Subscript> system

A new dichromium(III) cobalt(II) diphosphate(V) of the formula CoCr₂(P₂O₇)₂ was detected in the Co₃Cr₄(PO₄)₆–Cr(PO₃)₃ system. The new compound was obtained as a result of high-temperature solid-state reactions between CoCO₃, Cr₂O₃ and (NH₄)₂HPO₄ as well as between Cr(PO₃)₃ and Co₃Cr₄(PO₄)₆. CoCr₂(P₂O₇)₂ was characterized using XRD, DTA and IR methods. Results demonstrated that CoCr₂(P₂O₇)₂ crystallizes in the triclinic system and its unit cell parameters were calculated. Its infrared spectrum was presented. CoCr₂(P₂O₇)₂ melts incongruently at 1270±10 °C with a formation of solid α-CrPO₄. The compound Co₃Cr₄(PO₄)₆, component of the system under study, was obtained for the first time as a pure phase. Its thermal stability was also investigated. Co₃Cr₄(PO₄)₆ is stable in air up to 1410 ± 20 °C.     

Physicochemical properties of (CH<Subscript>3</Subscript>)<Subscript>2</Subscript>NH<Subscript>2</Subscript>Cl–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> composites

Composite solid electrolytes were synthesized from the organic salt dimethylammonium chloride (1–x)C₂H₈NCl–xAl₂O₃. Their physicochemical properties were studied. In the starting C₂H₈NCl salt, there is a phase transition at 39°C accompanied by an increase in conductivity by two orders of magnitude. The conductivity of the high-temperature phase is 9.3 × 10^–6 S/cm at 160°C. A differential scanning calorimetry study showed that the salt in the composites spreads over the oxide surface and at x > 0.6 the salt melting enthalpy decreases to zero. The conductivity of the resulting composites was studied by impedance spectroscopy. It was shown that heterogeneous doping leads to a sharp increase in ion conductivity to 7.0 × 10^–3 S/cm at 160°C and a decrease in the activation energy to 0.55 eV.     

Crystal structure of [Pb<Subscript>3</Subscript>(OH)<Subscript>4</Subscript>Co(NO<Subscript>2</Subscript>)<Subscript>3</Subscript>](NO<Subscript>3</Subscript>)(NO<Subscript>2</Subscript>)·2H<Subscript>2</Subscript>O

The structure of [Pb₃(OH)₄Co(NO₂)₃](NO₃)(NO₂)·2H₂O is determined by single crystal X-ray diffraction. The crystallographic characteristics are as follows: a = 8.9414(4) Å, b = 14.5330(5) Å, c = 24.9383(9) Å, V = 3240.6(2) ų, space group Pbca, Z = 8. The Co(III) atoms have a slightly distorted octahedral coordination formed by three nitrogen atoms belonging to nitro groups (Co–N_av is 1.91 Å) and three oxygen atoms belonging to hydroxyl groups (Co–O_av is 1.93 Å). The hydroxyl groups act as μ₃-bridges between the metal atoms. The geometric characteristics are analyzed and the packing motif is determined.     

Synthesis and structure of the complex [Mo<Subscript>3</Subscript>(μ<Subscript>3</Subscript>-S)(μ<Subscript>2</Subscript>-S<Subscript>2</Subscript>)<Subscript>3</Subscript>(Et<Subscript>2</Subscript>NCS<Subscript>2</Subscript>)<Subscript>3</Subscript>]I

The structure of tri-μ₂-disulfido-μ₃-thiotris(diethyldithiocarbamato)-S,S′-triangle-trimolybdenum iodide [Mo₃(μ₃-S)(μ₂-S₂)₃(Et₂NCS₂)₃]I was determined. The compound was characterized by differential thermal analysis and IR, Raman, and X-ray electronic spectroscopy.     

Phase formation in the system Zn(VO<Subscript>3</Subscript>)<Subscript>2</Subscript>–HCl–VOCl<Subscript>2</Subscript>–H<Subscript>2</Subscript>O

The phase and chemical compositions of precipitates formed in the system Zn(VO₃)₂–HCl–VOCl₂–H₂O at pH 1?3, molar ratio V⁴⁺: V⁵⁺ = 0.1?9, and 80°C were studied. It was shown that, within the range 0.4 ≤ V⁴⁺: V⁵⁺ ≤ 9, zinc vanadate with vanadium in a mixed oxidation state forms with the general formula Zn_xV⁴⁺ _yV⁵⁺ _2-yO₅ ? nH₂O (0.005 ≤ x ≤ 0.1, 0.05 ≤ y ≤ 0.3, n = 0.5?1.2). Vanadate Zn_xV₂O₅ ? nH₂O with the maximum tetravalent vanadium content (y = 0.30) was produced within the ratio range V⁴⁺: V⁵⁺ = 1.5?9.0. Investigation of the kinetics of the formation of Zn_xV₂O₅ ? nH₂O at pH 3 determined that tetravalent vanadium ions VO2+ activate the formation of zinc vanadate, and its precipitation is described by a second-order reaction. It was demonstrated that, under hydrothermal conditions at pH 3 and 180°C, zinc decavanadate in the presence of VOCl₂ can be used as a precursor for producing V₃O₇ ? H₂O nanorods 50–100 nm in diameter.     

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.     

Synthesis and study of uranyl arsenate (UO<Subscript>2</Subscript>)<Subscript>3</Subscript>(AsO<Subscript>4</Subscript>)<Subscript>2</Subscript> · 12H<Subscript>2</Subscript>O

A method for producing synthetic troegerite of composition(UO₂)₃(AsO₄)₂ · 12H₂. Owas developed. X-ray diffraction, IR spectrometry, X-ray fluorescence analysis, and scanning calorimetry were used to study its dehydration and thermal decomposition, to solve the structgure, and to determine X-ray diffraction and IR spectroscopic characteristics.     

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).     

Crystal structure of Cs[(UO<Subscript>2</Subscript>)<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(OH)] · H<Subscript>2</Subscript>O

Single crystals of Cs[(UO₂)₂(C₂O₄)₂(OH)] · H₂O were synthesized and structurally studied using X-ray diffraction. The compound crystallizes in monoclinic space group P2₁/m, Z = 2, with the unit cell parameters a = 5.5032(4) Å, b = 13.5577(8) Å, c = 9.5859(8) Å, β = 97.012(3)°, V = 709.86(9) ų, R = 0.0444. The main building units of crystals are [(UO₂)₂(C₂O₄)₂(OH)]^? layers of the A₂K ₂ ⁰² M² (A = UO ₂ ²⁺ , K⁰² = C₂O ₄ ^2? , and M² = OH^?) crystal-chemical family. Uranium-containing layers are linked into a three-dimensional framework via electrostatic interactions with outer-sphere cations and hydrogen bonds with water molecules.     

Simulating equilibrium processes in the Ga(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>–H<Subscript>2</Subscript>O–NaOH system

Equilibrium processes in the Ga(NO₃)₃–H₂O–NaOH system are simulated with allowance for the formation of precipitates of various compositions using experimental data from potentiometric titration and theoretical studies. The values of the instability constants are calculated along with the stoichiometric compositions of the resulting compounds. It is found that pH ranges of 1.0 to 4.3 and 12.0 to 14.0 are best for the deposition of gallium chalcogenide films.     

Separation of rare earth elements in the tributyl phosphate–Ln(NO<Subscript>3</Subscript>)<Subscript>3</Subscript>–Ca(NO<Subscript>3</Subscript>)<Subscript>2</Subscript> system in the counter current process

The 40-step extraction process to separate rare earth elements (RЕEs) according to the praseodymium–cerium line with the use of mixer–settler extractors in a 100% TBP–Ln(NO₃)₃–Ca(NO₃)₂ system is implemented. A lanthanum–cerium concentrate containing less than 0.03 wt % of the remaining REEs is obtained. The flow diagram of the separation process of a rare earth (RE) concentrate isolated from phosphogypsum is considered.     

Thermal analysis of the (Bi<Subscript>2</Subscript>O<Subscript>3</Subscript>)<Subscript>1−x</Subscript>(Y<Subscript>2</Subscript>O<Subscript>3</Subscript>)<Subscript>x</Subscript> pigments

The synthesis of new compounds based on Bi₂O₃ is investigated because they can be used as new ecological inorganic pigments. Chemical compounds of the (Bi₂O₃)_1−x(Y₂O₃)_x type were synthesized. The host lattice of these pigments is Bi₂O₃ that is doped by Y³⁺ ions. The incorporation of doped ions provides the interesting colours and contributes to a growth of the thermal stability of these compounds. The simultaneous TG-DTA measurements were used for determination of the temperature region of the pigment formation and thermal stability of pigments. This paper also contains the results of the pigment characterization by X-ray powder diffraction and their colour properties.     

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.     

Preparation of Li<Subscript>9</Subscript>Cr<Subscript>3</Subscript>(P<Subscript>2</Subscript>O<Subscript>7</Subscript>)<Subscript>3</Subscript>(PO<Subscript>4</Subscript>)<Subscript>2</Subscript> as cathode material for lithium ion batteries through sol–gel method

The compound Li₉Cr₃(P₂O₇)₃(PO₄)₂ has been successfully synthesized using sol–gel method. X-ray diffraction Rietveld refinement analysis indicates that single phase Li₉Cr₃(P₂O₇)₃(PO₄)₂ can be obtained under air condition and high purity nitrogen atmosphere. Scanning electron microscopy indicates that nanowires with lengths ranging from several to tens micrometers and diameters varying from 100nm to 500nm can be obtained in the Li₉Cr₃(P₂O₇)₃(PO₄)₂ compound heated under air condition. The electrochemical properties of Li₉Cr₃(P₂O₇)₃(PO₄)₂ sintered under N₂ as cathode material is reported for the first time. The XRD patterns of the electrodes before and after 30 cycles indicate that the Li₉Cr₃(P₂O₇)₃(PO₄)₂ keeps its original monodiphosphate structure.     

Crystal Structure of Neptunium(V) Acetate [(NpO<Subscript>2</Subscript>)<Subscript>2</Subscript>(OOCCH<Subscript>3</Subscript>)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)] ⋅ 2H<Subscript>2</Subscript>O

A new neptunium(V) complex [(NpO₂)₂(CH₃COO)₂(H₂O)] ? 2H₂O was synthesized and its crystal structure was determined. The unit cell parameters are: a = 24.007(10) Å, b = 6.779(3) Å, c = 8.076(3) Å, space group Pnma, Z = 4, V = 1314.2(9) ų, R = 0.049, wR(F²) = 0.105. The crystal structure of the compound is composed of neutral [(NpO₂)₂(CH₃COO)₂(H₂O)] layers and molecules of the water of crystallization. Each of the crystallographically independent neptunoyl ions performs a bidentate function thus forming a composite system of cation-cation bonds.     

Glass Formation in the Ternary System La<Subscript>2</Subscript>O<Subscript>3</Subscript>–As<Subscript>2</Subscript>S<Subscript>3</Subscript>–Er<Subscript>2</Subscript>O<Subscript>3</Subscript>

The boundaries of the glass formation region in the ternary system La₂O₃–As₂S₃–Er₂O₃ were found. Transparent glass of composition (La₂O₃)_0.03(As₂S₃)0.90(Er₂O₃)0.07 was studied by X-ray photoelectron and Raman spectroscopy. The intensities of the bands characterizing As–S, La–O, and Er–O bonds increased, and these bands were shifted toward higher energies. This was due to an increase in the covalence of these bonds and probably due to the formation of new bonds in the glasses. Samples in the glass formation region are resistant at 300 K to air, water, and organic solvents.     

A Raman Spectroscopic Study of Aqueous La(CH<Subscript>3</Subscript>CO<Subscript>2</Subscript>)<Subscript>3</Subscript> Solutions and La(CH<Subscript>3</Subscript>CO<Subscript>2</Subscript>)<Subscript>3</Subscript>·1.5 H<Subscript>2</Subscript>O(cr)

Aqueous solutions of La(CH₃CO₂)₃, NaCH₃CO₂ and La(ClO₄)₃ were studied using Raman spectroscopy. In dilute NaCH₃CO₂ solution, acetate is fully hydrated and forms only minor amounts of ion pairs. The characteristic Raman bands are discussed and assigned. In fairly dilute La(ClO₄)₃ solutions, the La³⁺(aq) ion occurs as the nonahydrate. The separation of the carboxylate bands, ν_as – ν_s (Δ-value), in NaCH₃CO₂(cr) compared to La(CH₃CO₂)₃·1.5H₂O(cr) correlates with the bonding type of acetate which is “ionic” in the former but bidentate chelating/tridentate chelating in the latter. Other acetate bands such as the deformation mode of the CO₂ moiety, δ CO₂, and the two rocking vibrations (ρ), as well as the C–C stretch show marked differences in their band positions in NaCH₃CO₂(cr) compared to the ones in La(CH₃CO₂)₃·1.5H₂O(aq). In a ternary solution of La(CH₃CO₂)₃/LaCl₃ with a molar ratio La³⁺(aq): \( {\text{CH}}_{3} {\text{CO}}_{2}^{ - } \)(aq) = 3.87: 1.00), the bands of the bound acetate on La³⁺ were characterized and compared to those of fully hydrated acetate, \( {\text{CH}}_{3} {\text{CO}}_{2}^{ - } \left( {\text{aq}} \right) \). In this solution, almost all acetate is ligated to La³⁺ in a bidentate fashion and two complex species could be identified (molar ratios La³⁺: \( {\text{CH}}_{3} {\text{CO}}_{2}^{ - } \)  = 1:1 and 1:2, respectively). In La(CH₃CO₂)₃ solutions in H₂O and D₂O strong acetato complexes are formed and the bands of the bound acetate were characterized and compared with the ones of the fully hydrated acetate modes. A dilution series down to 0.0037 mol·L^?1 in La(CH₃CO₂)₃(aq) and to 0.0150 mol·L^?1 in La(CH₃CO₂)₃(D₂O) showed that two acetate complexes are formed in these solutions. Again, it was shown that in these solutions the bound acetates on La³⁺ exist as bidentate ligands. DFT frequencies of the acetate on clusters {La(OH₂)₇O₂CCH₃)}²⁺ and {La(OH₂)₅(O₂CCH₃)₂}⁺ compared well with the measured values. By determining the ligation number, \( \bar{n} \), it can be established that in dilute solutions, below 0.04 mol·L^?1, a complex with a 1:1 stoichiometry (La³⁺: \( {\text{CH}}_{3} {\text{CO}}_{2}^{ - } \)) exists in equilibrium with “free” acetate while in more concentrated solutions a 1:2 complex also forms. La³⁺(aq) hydrolysis is slight and very small equilibrium concentrations of CH₃COOH were detected (C–C stretch at 893 cm^?1). From quantitative Raman measurements, K ₁ was determined to be 160 ± 10 at 22 °C.     

Crystal structure of Ba<Subscript>3</Subscript>[UO<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(NCS)]<Subscript>2</Subscript> · 9H<Subscript>2</Subscript>O

Single crystals of Ba₃[UO₂(C₂O₄)₂(NCS)]₂ · 9H₂O are synthesized and studied by X-ray diffraction. The crystals are orthorhombic, space group Fddd, Z = 16, and the unit cell parameters are a = 16.253(3) Å, b = 22.245(3) Å, c = 39.031(6) Å. The main crystal structural units are mononuclear complex groups [UO₂(C₂O₄)₂NCS]^3? of the crystal-chemical family (AB ₂ ⁰¹ M¹ (A = UO ₂ ²⁺ , B⁰¹ = C₂O ₄ ^2? , M¹ = NCS^?) of the uranyl complexes linked into a three-dimensional framework by electrostatic interactions and hydrogen bonds involving oxalate ions and water molecules.     

Porous xerogels with a bifunctional surface layer of the composition ≡Si(CH<Subscript>2</Subscript>)<Subscript>3</Subscript>SH/≡Si(CH<Subscript>2</Subscript>)<Subscript>2</Subscript>H<Subscript>3</Subscript>

The sol-gel method with ethanol as a solvent and fluoride ion as a catalyst was used to prepare polysiloxane xerogels containing both 3-mercaptopropyl and n-propyl groups in the surface layer. An increase in the relative amount of n-propyltriethoxysilane in the initial reaction solution was found to result in the formation of xerogels with developed porous structures, which was accompanied by an increase in the specific surface area from 370 to 550 m²/g; simultaneously, other porous structure parameters such as sorption volume and pore size exhibited a tendency to increase. Atomic-force microscopy was used to show that the xerogels synthesized comprised aggregates of mean size 30 nm. An analysis of the IR and ¹³C cross-polarization magic angle spinning NMR data led us to conclude that the surface layer of bifunctional xerogels contained not only 3-mercaptopropyl and n-propyl groups but also silanol groups, part of nonhydrolyzed alkoxy groups, and H-bonded water molecules. The ²⁹Si cross-polarization magic angle spinning NMR spectra revealed the presence of structural units of the compositions T¹ [(≡SiO)Si(OR’)₂(CH₂CH₂CH₃) and/or (≡SiO)Si(OR’)₂(CH₂)₃SH, R’ = H, OCH₃, or OC₂H₅], T² [(≡SiO)₂Si(OR’)(CH₂CH₂CH₃) and (≡SiO)₂Si(OR’)(CH₂)₃SH], and T³ [(≡SiO)₃SiCH₂CH₂CH₃ and (≡SiO)₃Si(CH₂)₃SH] in the xerogels synthesized.