卷 58, 编号 8 (2017)

Reactive deposition processes of tantalum carbide are studied experimentally and theoretically in the Ta–C–Si–O–F system. It is shown that Sio₂ substantially affects the carbide formation process. This is expressed in a decreased efficiency of tantalum transfer from the source zone to the crystallization zone, the possibility of bilateral transport of tantalum to carbon and carbon to tantalum, the complicated composition of condensed phases in the equilibrium with the gas phase. Aspects of preparing single crystal tantalum oxyfluoride are considered.

To produce novel thin-film spintronic materials based on a thermodynamic simulation, condensed phases with a complex composition are deposited in Si–С–N–H–M systems (M = Fe, Co, Ni) in a wide temperature range of 500-1300 K. As a result of the simulation CVD diagrams of Fe–Si–C–N–H(He), Co–Si–C–N–H(He), and Ni–Si–C–N–H(He) systems are obtained which enable the optimization of the synthesis process for film materials such as SiC_xN_yFe_z, SiC_xN_yCo_z, and SiC_xN_yNi_z. SiC_xN_yFe_z films are experimentally deposited from a gas mixture containing ferrocene (C₅H₅)₂Fe, organosilicon compound 1,1,1,3,3,3-hexamethyldisilazane HNSi₂(CH₃)₆ (HMDS) under reduced pressure in the temperature range 1073-1273 K. The dependence of the physicochemical and functional properties of SiC_xN_yFe_z films on the synthesis conditions is found by a comples of modern research techniques such as IR and Raman spectroscopy, EDS, XPS, SEM, HREM, and synchrotron radiation powder XRD (SR XRD). By the Faraday method and electron paramagnetic resonance (EPR) the magnetic properties of the films are analyzed. It is shown that at a synthesis temperature of 1123 K the films are paramagnetic, and at a higher deposition temperature of 1273 K they are ferromagnetic.

The possibilities of using powder X-ray diffraction methods in the study of carbon materials are discussed. To determine the phase composition of the crystalline materials the X-ray phase analysis is employed; the real structure is established by the harmonic analysis of diffraction profiles; the structural features and phase composition of the nanomaterials are found by the radial electron density distribution function.

Novel volatile heterocomplex compounds based on copper(II) and palladium(II) fluorinated β-diketonates are studied. The crystals of the synthesized compounds are shown to be composed of 1D coordination polymers in the form of chains of alternating molecules of monometallic complexes. The crystallographic data for [Cu(hfa)₂∙Pd(zif)₂] are as follows: C₂₆H₂₂F₁₈O₁₀CuPd, P2₁/c, a = 7.9947(18) Å, b = 19.277(4) Å, c = 13.609(3) Å, β = 118.298(15)°, V = 1846.7(7) ų, Z = 2, d = 1.810 g/cm³. The thermal properties of the compounds are examined by TG-DTA and vacuum sublimation. The complexes are studied as the precursors for producing copper-palladium alloy films by chemical vapor deposition. It is demonstrated that bimetallic alloy coatings with a ratio Cu/Pd = 1:1 can be prepared from [Cu(hfa)₂∙Pd(zif)₂].

We systemize the experimental data on the relationship of the specific electrical resistance, density, structure, and composition of thin ruthenium layers (TRLs) synthesized in the temperature range 160-310 °C by pulsed chemical vapor deposition with a carbonyl-diene precursor Ru(CO)₃(C₆H₈) and NH₃ and N₂O as second reagents. The main impurity in TRLs after their deposition and annealing is carbon with a concentration of ~30-50 at.%. To increase the density and decrease the electrical resistance of TRLs to values below 50 μOhm∙cm it is reasonable to use N₂O in the synthesis and also to apply the subsequent thermal annealing of TRLs at temperatures up to 700 °C, which improves the crystal structure of the layers.

We present the principles of stoichiography and a reference-free stoichiographic differential (separating) dissolution method used to study the composition and structure of thin films and nanostructured systems: HTS films with 123 different compositions, Al–Au–Sn–Co–Mn, Si/SiO₂/Ni(Cr)–Cu–Cu2S, Cr–Cu–S, and Cu–S multilayer films, Bi–Ti–O films on Ru/SiO₂/Si, Mn_1–xZn_xS, and ZnS–EuS supports, and also nanostructured manganese ferrite in borate glass matrices, nanodisperse composite sorbents and the Co–Si–Pt–O/Al₂O₃ catalyst modified by Pt nanoparticles, and oxide catalyst precursor Fe₂Co/Al₂O₃ for the synthesis of carbon nanotubes.

The technique for growing CH₃NH₃PbI₃ single crystals from saturated solutions in concentrated hydroiodic acid is improved by introducing a reducing agent (hypophosphorous acid). The structure of perovskite is confirmed by single crystal XRD. By energy dispersive spectroscopy and X-ray photoelectron spectroscopy it is established that the stoichiometry of the grown crystals corresponds to the CH₃NH₃PbI₃ compound. Changes in the photoluminescence intensity during in-air measurements show that the crystals synthesized using the reducing agent are more stable in the external environment with laser exposure than without it.

We present the results of studying the structure of gold nanoparticles synthesized on the silicon surface by two techniques: pulsed laser ablation and magnetron sputtering. The surface morphology is examined by scanning electron microscopy. The structure of the obtained gold nanoparticles is analyzed by transmission electron microscopy and electron diffraction. It is shown that nanoparticle sizes and crystal structures can be controlled by their thermal annealing. Mechanisms occurring during annealing of thin gold films and also their effect on the formation of nanoparticles with different structures are investigated.

The publication considers the modifying effect of refractory zirconium carbide in determining elements by hydride generation atomic absorption spectrometry. It is shown that the nature of binding of atoms of the analytes consists in the ability of the ZrC surface to strong adsorption. For As, Cd, Pb, Sb, Se, Te elements the adsorption energies of atoms on the ZrC(100) surface are calculated by the density functional theory. It is found that the necessary condition for adsorption is the preliminary cleaning of the ZrC surface from chemisorbed hydrogen. Correlation is demonstrated between the pyrolysis temperature that is maximum achievable for the analyte in the specimen with the adsorption energy of its atomic form on the ZrC(100) surface.

The preferential oxidation (PROX, CO + H₂ + O₂ → CO₂ + H₂O) of the CO reaction in an H₂ stream is the simplest and most cost-effective method to remove CO gas to less than 10 ppm in reformed fuel gas. We study the mechanism of PROX of the CO reaction in the H₂ stream catalyzed by Cu_nNi (n = 3-12) clusters using a density functional theory (DFT) calculation to investigate bimetallic effects on the catalytic activation. Our results indicate that the Cu₁₂Ni cluster is the most efficient catalyst for H₂ dissociation and the Cu₆Ni cluster is the most efficient catalyst for CO-PROX in excess hydrogen among Cu_nNi (n = 3-12) clusters. To gain insight into the adsorption and dissociation of the H₂ molecule effect in the catalytic activity over the Cu₁₂Ni cluster and the potential energy surfaces about PROX of CO oxidation on the Cu₆Ni cluster, the nature of the interaction between the adsorbate and substrate is analyzed by detailed electron local densities of states (LDOS) as well as molecular structures.

The microwave synthesis of quantum dots (QDs) based on zinc and manganese sulfides and oxides in a water-ethanol medium is proposed. The sample synthesized is characterized by X-ray diffraction (XRD), photoluminescence, X-ray absorption near edge structure (XANES), and extended X-ray absorption fine structure (EXAFS) spectroscopy. The XRD analysis shows the presence of the hexagonal ZnS phase of wurtzite type with an average nanocrystal size of 4.5 nm and manganese oxide Mn₃O₄ (hausmannite phase) with an average particle size of 12.5 nm in the sample under study, but does not provide the unambiguous conclusion about the doping of ZnS nanoparticles with Mn atoms. Although the analysis of the zinc and manganese K-edge XANES spectra suggests that the synthesized QD sample is a ZnMnS solid solution (~11%), a significant amount of a by-product (manganese oxide Mn₃O₄ of the hausmannite phase, ~89%) is formed.

The X-ray diffraction (XRD) study of boron carbide obtained by self-propagating high-temperature synthesis reveals monoclinic single crystals. This is in contradiction with the literature data that boron carbide crystals are hexagonal. According to the XRD data, hexagonal and monoclinic crystals of boron carbide have almost identical structures. The article considers one of the possible reasons for the occurrence of monoclinic boron carbide crystals: the crystal symmetry reduction is due to distortions in structural units (icosahedra and/or triatomic groups). This induces the appearance of reflections that should be extinguished in hexagonal crystals. To check this hypothesis, theoretical XRD patterns of hypothetical boron carbide crystals with distorted units are calculated. The calculation results confirm our hypothesis.

(2-Chloro-4-(phenylthio)phenyl)(3-methyl-1-phenyl-5-(phenylthio)-1H-pyrazol-4-yl)methanone was obtained by accident. In order to know the structure of this product, the compound was isolated by column chromatography and recrystallized from EtOH. The compound was characterized by X-ray diffraction. The compound crystallized in the triclinic space group P-1 with a = 9.909(2) Å, b = 11.824(2) Å, c = 13.056(3) Å, α = 63.309(3)°, β = 89.964(4)°, γ = 67.727(3)°, V = 1237.7(4) ų, Z = 2 and R = 0.0414.

LnTe₃ (Ln = La, Ho) single crystals are produced by the interaction of elementary compounds in an alkali halide melt. The structures of the obtained compounds are determined by single crystal X-ray diffraction. It is found that LaTe₃ crystallizes in the space group Ama2 with the following parameters: a = 4.4195(2) Å, b = 26.2644(11) Å, c = 4.4028(2) Å. As for HoTe₃, the space group Cmcm with the following parameters a = 4.2994(18) Å, b = 25.393(10) Å, c = 4.3021(17) Å is determined.

A polymeric dinuclear copper(II) complex with a Schiff base based on 3-formyl-4-hydroxy-6-methylpyrone and 1,3-diaminopropanol-2 is synthesized. The crystal structure of the complex is determined by single crystal XRD (CCDC No. 1518681). The magnetic properties of the complex are studied. A ferromagnetic exchange interaction between copper(II) ions is demonstrated.

The structure of two lanthanide (Ln = Nd, Ho) complexes with dipivaloylmethane (Hdpm) is studied at 150(2) K by single crystal X-ray diffraction. The crystallographic data are as follows for [Nd(dpm)₃]₂: space group P2₁/n, a = 12.3281(3) Å, b = 27.8118(6) Å, с = 21.9035(5) Å, β = 105.241(1)°, V = 7245.8(3) ų, Z = 4, R = 0.0333; for [Ho(dpm)₃]₂: space group P2₁/n, a = 12.2067(6) Å, b = 27.5626(13) Å, с = 21.8624(10) Å, β = 105.188(1)°, V = 7098.6(6) ų, Z = 4, R = 0.0321. Both structures are molecular and consist of neutral [Ln(dpm)₃]₂ dimeric molecules. The thermogravimetric studies demonstrate that Ln(dpm)₃ volatility increases in the series from [La(dpm)₃]₂ to Yb(dpm)₃.

Transparent, unidirectional single crystals of sodium dihydrogen phosphate-doped glycine phosphite (NaDP–GPI) are grown by the Sankaranarayanan-Ramasamy method. The good quality crystal is obtained under controlled thermal conditions. The functional groups and melting temperature of NaDP–GPI single crystals are analysed. The phase transition temperature of NaDP–GPI is calculated from the dielectric studies. The mound-like patterns are observed on the surface of the crystal. The growth process under the controlled thermal condition was observed by optical studies. The obtained results are discussed in detail.