


Vol 62, No 8 (2017)
- Year: 2017
- Articles: 18
- URL: https://journal-vniispk.ru/0036-0236/issue/view/10248
Synthesis and Properties of Inorganic Compounds
High-temperature properties of new perovskite-like oxides
Abstract
New complex oxides of composition Pr1–yCayFe0.5 + x(Mg0.25Mo0.25)0.5–xO3, 0.0 ≤ x ≤ 0.1, 0.42 ≤ y ≤ 0.8 having an orthorhombically distorted perovskite structure have been prepared. The thermal expansion and electric conductivity of the new phases have been studied in the temperature range between 100–900°C. The results of our study imply that thin films of the oxides studied can be treated as electrode materials for symmetric solid-oxide fuel cells.



Investigation of the substitution at the anionic positions BaT2As2 (T = Fe, Ni) superconductors
Abstract
The possibilities of electron/hole doping of two ternary arsenides, BaFe2As2 and BaNi2As2, via partial substitution at the arsenic position by 16 and 14 group elements, have been studied. While no substitution has been observed for chalcogens, BaFe2As2 incorporates Sb, Si, and Ge at the As site; BaNi2As2 incorporates Sb, Ge, Sn, and Pb. The observed results can be tentatively explained suggesting that 14 group elements are incorporated into the BaT2As2 structures as X6−2 dumbbells.



Modifying additives affect the properties of Y2O3–Al2O3–SiO2 system
Abstract
The effects caused by modifying additives, namely nonionic surfactants (Tween 80 and Neonol AF 9-6) and oxides (B2O3 and HfO2), on the rheology, film formation, and phase formation in the yttrium aluminum silicate system prepared by sol–gel technology were studied. The effect of 1 wt % HfO2 additions on the activation energy of crystallization was studied.



Coordination Compounds
Dioxomolybdenum(VI) complexes with substituted salicylidene-2-furfurylimines: the crystal and molecular structure of 4-hydroxysalicylidene-2-furfurylimine
Abstract
4-Hydroxysalicylidene-2-furfurylimine HL4 and complex МоО2Cl2 · 2HL4 were prepared. The HL4 structure was determined by X-ray crystallography. The two crystallographically nonequivalent molecules have similar structures and are in zwitterionic form.



Tris(5-bromo-2-methoxyphenyl)bismuth dicarboxylates [(C6H3(Br-5)(MeO-2)]3Bi[OC(O)CHal3]2 (Hal = F, Cl): synthesis and structure
Abstract
Tris(5-bromo-2-methoxyphenyl)bismuth dicarboxylates [(C6H3(Br-5)(MeO-2)]3Bi[OC(O)CHal3]2, Hal = F (II) and Cl (III), have been synthesized by the reaction between tris(5-bromo-2-methoxyphenyl)bismuth (I) and trifluoroacetic acid and thrichloroacetic acid, respectively, in the presence of hydrogen peroxide in ether. According to X-ray diffraction data, a crystal of complex I contains two types of crystallographically independent molecules (a and b) both with a trigonal pyramid configuration. The bismuth atoms in complexes II and III have a distorted trigonal bipyramidal coordination with carboxylate substituents in axial positions. Axial OBiO angles are 166.3(3)° (II) and 171.6(2)° (III); equatorial CBiC angles are 118.0(3)°–123.1(3)° (II) and 113.6(3)°–127.4(3)° (III). Bi–C bond lengths are 2.189(7)–2.200(8) Å (II) and 2.190(8)–2.219(7) Å (III), and Bi–О distances are 2.280(6), 2.459(16) Å (II) and 2.264(5), 2.266(5) Å (III). Intramolecular contacts between the central atom and the oxygen atoms of carbonyl groups (Bi···O 3.028(9), 3.162(9) Å (II); 3.117(9), 3.202(9) Å (III)) are observed at maximum equatorial angles. The oxygen atoms of methoxy groups are coordinated to the bismuth atom. The Bi···O distances in complexes II and III (3.028(16), 3.157(16), 3.162(16) and 3.17(16), 3.143(16), 3.202(16) Å, respectively) are slightly longer than in complex I (3.007(9)–3.136(4) Å).



Theoretical Inorganic Chemistry
Electronic properties of titanium dioxide nanotubes doped with 4d metals
Abstract
The effect of 4d-metal dopants on the densities of states of hexagonal TiO2 nanotubes has been calculated by the linearized augmented cylindrical wave method. It has been demonstrated that the substitution of Nb, Mo, Tc, or Pd atoms for a part of Ti atoms leads to a decrease in the band gap width of the material due to the formation of impurity levels in the band gap of TiO2. Doping TiO2 nanotubes with these metals is a promising way to produce materials for electrodes for electrochemical photolysis of water. Doping with Y, Rh, or Ag leads to the displacement of the absorption edge from the UV to the visible range owing to a considerable broadening of the valence and conduction band edges; Zr, Ru, and Cd have a lower disturbing effect on the electronic levels of TiO2.



Nonaqueous LiNafion-based polymeric electrolyte: quantum-chemical modeling
Abstract
In the framework of the search for promising electrolytes for lithium-ion batteries, quantumchemical modeling of the structure, stability, and electronic properties of membranes based on LiNafion. nDMSO, n = 0–16) has been performed by the density functional theory method with inclusion of gradient correction and periodic conditions (PBE/PAW). Inasmuch as the key factor that determines the ionic conductivity is the degree of swelling of LiNafion in DMSO (according to calculations, for n = 8, the degree of swelling is close to 500%, and for n = 16, it is close to 700% by volume), similar membranes can be good candidates from the viewpoint of lithium ion transport (with barriers of 0.2–0.3 eV, which depend on n).



Prediction of new A3+B3+C2+O4 compounds
Abstract
Hitherto unprepared ABCO4 compounds (where A and B stand for tervalent metals (rA ≥ rB) and C stands for a divalent metal) are predicted. Criteria are found to predict the possibility for these compounds to crystallize in some type of structure (K2NiF4, CaFe2O4, YbFe2O4, or spinel) at room temperature and atmospheric pressure. The prediction is based only on the properties of elements and simple oxides. A special software system for computer-aided analysis of information is used for calculations involving pattern recognition based on use case.



Structural and electronic properties of XY-doped (AlN, AlP, GaN, GaP) C58 fullerenes: a DFT study
Abstract
Structural and electronic properties of C60 fullerene nano-cages doped with GaP, GaN, AlP, and AlN were performed by density functional theory (DFT) at the B3LYP method and 6-31G** basis set. The results exhibit that AlP-doped fullerene has the most gap energy (2.383 eV), and the lowest one refers to GaN (2.283 eV), and there is not considerable difference in the range of gap energies. Therefore, it is clear that GaN has the most potential to translate electron. Hence, the use of GaN-doped fullerene in electronical devices could be more acceptable than those of AlN, AlP, and GaP. To examine the effect of the corresponding doping on the thermodynamic parameters of these systems, we have investigated parameters such as chemical potential, chemical hardness, electrophilicity, and the highest electronic charge transferred in the related structures.



Physical Methods of Investigation
Electrochemical synthesis and structure of 2-amino-1-ethylbenzimidazole adducts of copper, cobalt, and zinc chelates in the N,N,S ligand environment
Abstract
2-Amino-1-ethylbenzimidazole (L1) adducts with copper(II), cobalt(II), and zinc(II) chelates of N,N,S tridentate tosylamino-functionalized mercaptopyrazole-containing Schiff base (H2L), resulting from condensation of 2-tosylaminoaniline with 1-phenyl-3-methyl-4-formylpyrazole-5-thiol, with the general formula [ML · L1] were obtained by electrochemical method. The structure and composition of the complexes were confirmed by the data of C, H, N elemental analysis, IR and 1H NMR spectroscopy, and magnetochemical and X-ray spectral measurements. The mononuclear structure of the copper(II) adduct with coordination bond located on the pyridine type endocyclic nitrogen atom of 2-amino-1-ethylbenzimidazole was proved by X-ray diffraction.



Synthesis, structure, and optical properties of iridium(III) complex with 1-benzyl-2-phenylbenzimidazole and 4,4'-dicarboxy-2,2'-bipyridyne
Abstract
A new cyclometalated iridium(III) complex [Ir(L)2(Hdcbpy)] (1) has been synthesized, where L is 1-benzyl-2-phenylbenzimidazole and Hdcbpy is monoprotonated 4,4′-dicarboxy-2,2′-bipyridine. The structure of complex 1 has been determined by X-ray diffraction. The optical properties of complex 1 have been studied, and the quantum yield of luminescence has been measured.



Physicochemical Analysis of Inorganic Systems
Phase equilibria, crystal structure at 1373 K and properties of complex oxides in the Nd–Co–Fe–O system
Abstract
Phase equilibria in the Nd–Co–Fe–O system were systematically studied at 1373 K in air. The homogeneity range and crystal structure of solid solution NdCo1–xFexO3 (0.0 ≤ x ≤ 1.0) have been studied by the X-ray powder diffraction method. The structural parameters of complex oxides have been refined by the full-profile Rietveld method. It was shown that all oxides reveal practically stoichiometric oxygen composition within the entire temperature range under investigation. The values of thermal expansion coefficients for the cobaltites NdCo1–xFexO3 (x = 0.3, 0.7) have been calculated within the wide temperature range in air. Chemical stability of NdCo1–xFexO3 (x = 0.3, 0.7) in respect to the solid electrolyte materials (Ce0.8Sm0.2O2–δ and La0.88Sr0.12Ga0.82Mg0.18O3-δ) was examined. Electrical conductivity of NdCo1–xFexO3 (x = 0.3, 0.7) was measured as a function of temperature within the range 300–1373 K in air. It was shown that substitution of cobalt for iron leads to the decrease of conductivity. The isothermal-isobaric cross-section of the phase diagram for the Nd–Co–Fe–O system at 1373 K in air has been presented.



Solubility in the system 2HCOONa + CaCl2 ⇄ (HCOO)2Ca + 2NaCl–H2O
Abstract
Phase and conversion equilibria in the quaternary reciprocal water–salt system 2HCOONa + CaCl2 ⇄ (HCOO)2Ca + 2NaCl–H2O at 25°C were studied for the first time to determine the concentration parameters of the production of calcium formate from sodium formate.



Phase formation in the system Zn(VO3)2–HCl–VOCl2–H2O
Abstract
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 ZnxV4+yV5+2-yO5 ∙ nH2O (0.005 ≤ x ≤ 0.1, 0.05 ≤ y ≤ 0.3, n = 0.5−1.2). Vanadate ZnxV2O5 ∙ 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 ZnxV2O5 ∙ 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.



Solubility diagrams of Na2SO4–Rb2SO4–MgSO4–H2O, Na2SO4–Cs2SO4–MgSO4–H2O, and K2SO4–Cs2SO4–MgSO4–H2O at 298.15 K
Abstract
The Pitzer ion-interaction was applied to calculate the solubility isotherms of quaternary systems Na2SO4–Rb2SO4–MgSO4–H2O and Na2SO4–Cs2SO4–MgSO4–H2O at 298.15 K. The results were compared with experimental data from the literature. Phase equilibrium of K2SO4–Cs2SO4–MgSO4–H2O has been predicted assuming that no new solid phases crystallize in them. The calculated phase diagram consists of five crystallization fields, three invariant points, and seven univariant curves. The five crystallization fields correspond to K2SO4, Cs2SO4, MgSO4 · 7H2O, Cs2SO4 · MgSO4 · 6H2O and K2SO4 · MgSO4 · 6H2O. The results could provide a theoretical basis for exaction ofrubidium and cesium from salt lake brine resources.



Physical Chemistry of Solutions
Study of triglycine complexation with Cu2+ ions in aqueous solution
Abstract
Composition and stability of triglycine complexes with Cu(II) ions in a wide range of concentration ratios at T = 298.15 K and I = 0.2 (KNO3) have been determined by potentiometric method. Existence of CuHL2+, CuHL2+, CuH2L2+2, CuL+, CuH–1L, CuH–2L–, CuH–3L2–, CuL2, CuH-1L-2, and CuH–2L2-2, species has been established.



Kinetic and fluorescent properties of tetraphenylporphine derivatives in acetonitrile
Abstract
The kinetics of formation of zinc complexes with 5,10,15,20-tetra(4-Cl-phenyl)porphine and 5,10,15,20-tetra(4-NH2-phenyl)porphine in acetonitrile in the range of 298–318 K are studied. It is found that peripheral substituents in tetraphenylporphine can slow down or accelerate the reaction of formation of zinc complexes in acetonitrile as observed by changes in kinetic rate constants. The fluorescence quantum yields of tetraphenylporphine derivatives and their zinc complexes also depend on the presence of electrondonating or electron-drawing substituents in the ligand structure.



Simulation of equilibria of formation of mono- and polynuclear heteroligand cobalt(II) and nickel(II) complexonates in aqueous solutions
Abstract
We report the results of our studies of the protolytic and coordination equilibria of formation of mono- and polynuclear heteroligand complexonates containing cobalt(II) and nickel(II) salts and EDTA, as well as monoamine complexons, such as iminodiacetic acid and hydroxyethyliminodiacetic acid. The experimental data obtained by absorption spectrophotometry were processed using the mathematical models that allowed us to assess the probability of existence of a broad range of complex species in the solution and to select the species sufficient for the experimental data to be reconstituted from them. The compositions of the polynuclear heteroligand cobalt(II) and nickel(II) complexonates were determined. The pH ranges of their existence were found; the equilibrium constants of the reactions and the stability constants of the resulting complexes were calculated. An assumption is made about their structure.


