


Vol 61, No 4 (2016)
- Year: 2016
- Articles: 21
- URL: https://journal-vniispk.ru/0036-0236/issue/view/10134
Physical Methods of Investigation
Magnetic properties of Cox(Cu0.5In0.5)1–xCr2S4 solid solutions
Abstract
The magnetic properties of Cox(Cu0.5In0.5)1–xCr2S4 (х = 0, 0.2, 0.5, 0.6) solid solutions between ferrimagnet СоCr2S4 (TC = 223 K) and antiferromagnet Cu0.5In0.5Cr2S4 (TN = 28 K) have been measured over wide ranges of fields (up 40 kOe) and temperatures (5–300 K). The major magnetometric data have been determined. Transition from one end-member of the solid solutions to the other occurs through an intermediate spin-glass phase.



Structure and properties of solid solutions based on bismuth niobate Bi3NbO7
Abstract
Solid solutions Bi3Nb1–yWyO7 ± δ, Bi3Nb1–yVyO7 ± δ, Bi3Nb1–yFeyO7 ± δ (y = 0.1–0.5; Δy = 0.1), and Bi3–xYxNb1–yWyO7 ± δ (x = 0.05, 0.1; y = 0–0.3; Δy = 0.1) have been studied. The homogeneity ranges of the solid solutions and crystal-chemical parameters have been determined by means of X-ray powder diffraction. The electrical conductivity of sintered samples has been studied by impedance spectroscopy. The joint introduction of yttrium and tungsten into the niobium sublattice does not lead to an increase in the conductivity of solid solutions, and the change of the dopant type has no noticeable effect on this conductivity.



Effect of polyoxomolybdate nanocluster doping on the dielectric characteristics of polyvinyl alcohol nanocomposite films
Abstract
Electrophysical parameters of polyvinyl alcohol (PVA) films comprising nanocluster molybdenum-based polyoxometalates (POMs), namely electrical conductivity, dielectric loss tangent, and dielectric permittivity, have been studied. Frequency and concentration curves have been plotted for these properties, which characterize the relaxation parameters of polymeric macromolecules and interactions of the polymer with spheroidal Keplerate POMs (Mo132 and Mo72Fe30) and toroidal POMs (Mo138).



Crystal Structures of α- and β-SrCeCuS3
Abstract
The crystal structure of SrCeCuS3, a complex sulfide synthesized for the first time, has been solved using X-ray powder diffraction data. The crystals are orthorhombic, space group Pnma. SrCeCuS3 has two polymorphs: the high-temperature phase of Ba2MnS3 structural type (a = 8.1393(3) Å, b = 4.0587(2) Å, c = 15.9661(2) Å) and the low-temperature phase isostructural to BaLaCuS3 (a = 11.1626(2) Å, b = 4.0970(2) Å, c = 11.5307(1) Å). The incongruent melting temperature and enthalpy of SrCeCuS3 are, respectively, 1486 ± 3 K and 13.4 ± 1.5 J/g.



Deposition conditions, composition, and structure of chemically deposited In2Se3 films
Abstract
In2Se3 films up to 300 nm thick have been obtained for the first time by hydrochemical deposition on glass, glass ceramic, and molybdenum substrates in the In(NO3)3–C4O6H6–CSeN2H4 system with the use of selenourea as a chalcogenizing agent. The phase and element composition and morphological features of layers obtained at 353 and 363 K have been studied by X-ray photoelectron spectroscopy, energy-dispersive electron probe X-ray microanalysis, and scanning electron microscopy. The optical band gap width has been determined.



Physicochemical Analysis of Inorganic Systems
Stable triangle (LiF)2–(KI)2–Li2CrO4 of the quaternary reciprocal system Li,K∥F,I,CrO4
Abstract
The quaternary reciprocal system Li,K||F,I,CrO4 was partitioned into stable simplexes using graph theory. The system consists of five stable tetrahedra separated by four stable triangles. The chemical interaction between components was described based on the material balance written with account for occurring chemical reactions. Phase equilibria in the quasi-ternary system (LiF)2–(KI)2–Li2CrO4 were studied for the first time; in this system, the temperature and composition of a ternary eutectic were determined. The limited solubility of two liquid phases manifests itself in the concentration region adjacent to the LiF–KI quasibinary system. A three-dimensional model of the phase complex of the system was constructed in temperature– concentration coordinates.



Interaction in the systems TlBiSe2–Tl9BiSe6–PbSe and Tl9BiSe6–Tl4PbSe3–PbSe
Abstract
Phase equilibria in the systems TlBiSe2–Tl9BiSe6–PbSe and Tl9BiSe6–Tl4PbSe3–PbSe were studied by differential thermal, X-ray powder diffraction, and microstructural analyses. State diagrams of the quasi-binary sections Tl9BiSe6–Tl4PbSe3, TlBiSe2–PbSe, and Tl9BiSe6–PbSe were constructed, and so were projections of liquidus surfaces and isothermal sections at 600 K for the secondary quasi-ternary systems TlBiSe2–Tl9BiSe6–PbSe and Tl4PbSe3–Tl9BiSe6–PbSe. The coordinates of invariant points and the boundaries of solid solutions were determined.



Phase equilibria in the Na,K,Mg,Ca∥SO4,Cl–H2O system at 50°С in the polyhalite crystallization region
Abstract
Phase equilibria of the Na,K,Mg,Ca||SO4,Cl–H2O system at 50°С in the polyhalite (K2SO4 · MgSO4 · 2CaSO4 · 2H2O) crystallization region were studied using the translation method. Polyhalite was found to be involved, as an equilibrium phase of the title system at 50°С, in 17 invariant points, 36 monovariant curves, and 24 divariant fields. A fragment of equilibrium phase diagram of the title system in the polyhalite crystallization region was constructed.



Study of the stable tetrahedra LiF–KBr–LiKMoO4–LiKWO4 and LiF–KBr–K2MoO4–K2WO4 of the quinary reciprocal system Li,K∥F,Br,MoO4,WO4
Abstract
The stable tetrahedra LiF–KBr–LiKMoO4–LiKWO4 and LiF–KBr–K2MoO4–K2WO4 of the quinary reciprocal system Li,K||F,Br,MoO4,WO4 were studied by differential thermal and X-ray powder diffraction analyses. It was determined that the tetrahedra contain no invariant points. Continuous series of solid solutions LiKMoxW1–xO4 and K2MoxW1–xO4 do not decompose.



Physical Chemistry of Solutions
Thermodynamic characteristics of complexation between Ho3+ and ethylenediamine-N,N'-disuccinic acid in aqueous solutions at 298.15 K
Abstract
The thermodynamic characteristics of complexation between ethylenediamine-N,N'-disuccinic acid (H4Y; EDDA) and Ho3+ ion were determined calorimetrically and potentiometrically at 298.15 K and ionic strengths of 0.1, 0.5, 1.0, and 1.5 (KNO3). The logK, ΔrG, ΔrH, and ΔrS values for the formation of HoY– and HOHY complexes were calculated at the studied and zero ionic strength values. The changes in thermodynamic parameters of the reactions are discussed.



Experimental study and computer modeling of Ni(II) and Cu(II) complexation with ceftazidime
Abstract
The protonation constants of the anion of the cephalosporin antibiotic ceftazidime Ctzd– and formation constants of its complexes with Ni2+ and Cu2+ have been determined by pH metric titration at 25°С and ionic strength 0.1 (KNO3): logβ(HCtzd) = 4.82 ± 0.04, logβ(H2Ctzd+) = 7.62 ± 0.06, logβ(H3Ctzd2+) = 9.23 ± 0.09, logβ(NiCtzd+) = 4.04 ± 0.03, logβ(Ni(Ctzd)2) = 6.41 ± 0.06, and logβ(CuCtzd+) = 5.03 ± 0.06. The potentiometric method has failed to reveal the complexation of Ctzd– with Co2+, Zn2+, and Cd2+. The composition of the [Ni(Ctzd)2] and [CuCtzd]+ complexes has been confirmed by spectrophotometry. The computer models of the [NiCtzd]+ and [CuCtzd]+ complexes have been calculated by the DFT method with the use of the B3LYP hybrid functional and the LACV3P**++ basis set.



Facile synthesis of gold nanoparticles in aqueous acrylamide solution
Abstract
A method is advanced for preparing gold nanoparticles (NPs) at 50°C in aqueous acrylamide (AAm), which has the dual function of a reducing agent for HAuCl4 and a protective ligand for NPs. Nanoparticles have gold cores with the average size dAu = 20.9 ± 3.6 nm. The growth kinetics of NPs has been studied. Films of NPs have been produced on glass, silica, silicon, and polyethylene terephthalate (PET) substrates. The NPs and films have been characterized by UV-Vis and IR spectroscopy, X-ray powder diffraction, transmission and scanning electron microscopy, and atomic-force microscopy.



Synthesis and Properties of Inorganic Compounds
The effect of synthesis conditions on the structure of compounds formed in the Dy2O3–TiO2 system
Abstract
Crystallization and phase transition processes taking place in the Dy2O3–TiO2 system during the isothermal annealing of the precursors synthesized by co-precipitation were studied. The phase composition of the obtained powders is determined by not only the chemical composition of the precursor (Dy2O3: TiO2 ratio) and annealing temperature but also by the procedure of precursor synthesis determining the uniformity of Dy and Ti distribution in the precursor precipitate. Higher homogeneity of precursor particles provides the formation of almost single-phase nanocrystaline dysprosium titanate (Dy2TiO5, Dy2Ti2O7) powders at annealing temperatures of 800–1000°C.



Synthesis of Nb2O5〈B〉 solid precursors and LiNbO3〈B〉 batches and their phase compositions
Abstract
A process has been developed for preparing boron-doped niobium pentoxides Nb2O5〈B〉 to be used as precursors in the sysnthesis of nithium biobate batches LiNbO3〈B〉 having tailored dopant concentrations. Solutions of various origins were used to isolate Nb2O5〈B〉. A method has been advanced to account for boron loss as volatile compounds upon the heat treatment of niobium hydroxide in order to determine the boron amount to be added to niobium hydroxide in the form of H3BO3. The boron concentration in LiNbO3〈B〉 during lithium niobate synthesis is shown to be independent of the origin of the Nb2O5〈B〉 precursor with the same as-batch boron concentration. The phase compositions of Nb2O5〈B〉 and LiNbO3〈B〉 have been characterized by X-ray powder diffraction and IR spectroscopy and boron concentrations have been determined for the synthesis of single-phase lithium niobate batches for use in the production of optically uniform single crystals and pore-free piezoelectric ceramics.



Synthesis and heat capacity of NdVO4 in the temperature range of 384–859 K
Abstract
Heat capacity of NdVO4 was determined in the temperature range of 384–859 K using differential scanning calorimetry. The thermodynamic functions (H°(T)–H°(384 K), S°(T)–S°(384 K), and Φ°) of neodymium orthovanadate were calculated using the experimental Cp = f(T) values. The structure of NdVO4 was studied at 298 and 973 K.



Corrosion-resistant composite coatings on biodegradable magnesium alloys: In vitro studies
Abstract
A composite coating was formed on MA8, MA14, and MA12 magnesium alloys by plasma electrolytic oxidation with subsequent immersion of samples into a superdispersed polytetrafluoroethylene suspension. In vitro volumetry determined that using this coating significantly reduces the magnesium alloy dissolution rate. It was shown that superdispersed polytetrafluoroethylene seals pores of the coating, thus reducing the corrosion rate in an artificial medium that mimics human blood by ionic composition. However, the surface of the calcium phosphate coating (Ca: P = 1.61) containing hydroxyapatite remains open for contact with the environment. The obtained data suggested that the proposed method for surface treatment of MA8, MA14, and MA12 alloys is promising for producing biodegradable protective coatings on magnesium medical implants.



Synthesis of nanosized group IV borides in ionic melts of anhydrous sodium tetraborate
Abstract
The preparation of nanosized Group IV metal diborides by reacting powdery titanium, zirconium, and hafnium with fine-grained boron in Na2B4O7 ionic melts in the temperature range 600–850°C has been studied. Nanosized titanium, zirconium, and hafnium diborides are formed at temperatures of at least 750°C.



Coordination Compounds
Malonatobenzhydrazidediaquacobalt(II) hydrate: Synthesis, crystal and molecular structures
Abstract
The coordination compound [Co(L)(Mal)(H2O)2]H2O (I) (L is benzhydrazide, H2Mal is malonic acid) has been synthesized and studied by IR spectroscopy, thermogravimetry, and X-ray diffraction. Crystals are triclinic, a = 7.610(4) Å, b = 7.854(2) Å, c = 12.751(2) Å, α = 75.12(3)°, β = 88.01(3)°, γ = 80.26(3)°, Z = 2, space group \(P\bar 1\). The structure is molecular. The Co2+ atom has a distorted octahedral coordination. The Co-O and Co-N bond lengths are 2.031-2.129(4) and 2.157(5) Å, respectively. The endocyclic O1Co1N1 bond angles are 77.3(2)° and 90.0(2)° in the five- and six-membered chelate rings, respectively. Molecules of complex I are linked via a great number of hydrogen bonds. The C…C contacts between phenyl rings additionally strengthen the structure.



Crystal structure of thallium(I) 2-thiobarbiturate
Abstract
The crystal and molecular structures of thallium(I) thiobarbiturate C4H3N2O2STl (C4H4N2O2S is 2-thiobarbituric acid, Н2ТВА) have been determined. Crystallographic data for Tl(НТВА) are a = 11.2414(7) Å, b = 3.8444(3) Å, с = 14.8381(9) Å, β = 99.452(2)°, V = 649.00(7) Å3, space group P2/с, Z = 4. Each of the two independent thallium ions is bonded to four oxygen and two sulfur atoms to form a distorted tetrahedron. N‒H…O and C‒H…S hydrogen bonds form a branched three-dimensional network. The structure is also stabilized by π‒π interaction between heterocyclic НТВА- ions. The IR spectra of Tl(НТВА) agree with X-ray powder diffraction data. The compound is also stable below 280°C, and Tl2SO4 is one of the thermolysis products in an oxidative medium in the region of 500‒650°C.



Synthesis and crystal structure of hexakis(ε-caprolactam)lutetium(III) hexa(isothiocyanato)chromate(III) bis(ε-caprolactam) solvate
Abstract
The reaction between Lu(NO3)3, K3[Cr(NCS)6], and ε-caprolactam (ε-C6H11NO) in an aqueous solution afforded complex [Lu(ε-C6H11NO)6][Cr(NCS)6] · 2(ε-C6H11NO) (I), the structure of which was determined by IR spectroscopy and X-ray diffraction. Crystals of I are triclinic, space group \(P\bar 1\), Z = 1, a = 12.1371(7) Å, b = 12.2082(7) Å, c = 12.7090(7) Å, α = 67.2920(10)°, β = 87.9130(10)°, γ = 82.9410(10)°, V = 1723.86(17) Å3, ρcalc = 1.426 g/cm3.



Silver complexes [Ph3PCH2CH2PPh3]2+[Ag2Cl4]2–, [Ph3PCH2OCH3]2+[Ag2Cl4]2-, [Ph3P(i-Am)]2+[Ag2Br4]2−, [Ph3PC6H11-cyclo]2+[Ag2Br4]2−, [Ph3PCH2Ph]2+[Ag2Br4]2−, and [Ph3PCH=CH2]n+[Ag2Br3]n-, [Me4P]n+[Ag2Br3]n-: Synthesis and structure
Abstract
Silver complexes [Ph3PCH2CH2PPh3]2+[Ag2Cl4]2‒ (I), [Ph3PCH2OCH3]2+[Ag2Cl4]2- (II), [Ph3P(i-Am)]2+[Ag2Br4]2- (III), [Ph3PC6H11-cyclo]2+[Ag2Br4]2- (IV), [Ph3PCH2Ph]2+[Ag2Br4]2- (V), [Ph3PCH = CH2]n+[Ag2Br3]n- (VII) have been synthesized by the reaction between tetraorganylphosphonium halides and silver chloride or silver bromide in dimethylsulfoxide. According to X-ray diffraction data, the ionic complexes are built of tetraorganylphosphonium cations and binuclear (I‒V) or polynuclear (VI, VII) anions. In the anions of complexes VI and VII, silver atoms are tetracoordinated, and bromine atoms have coordination numbers of 2 and 4.


