Home – Home – Jornals – Avtometriya 2011 number 1

Diamonds from the Siberian Platform have been studied in terms of their polygenesis, specifically their origin from different types of primary sources. Five types of diamonds have been distinguished, which might have originated from different primary sources, and their distribution over the platform has been shown. The sources of two types of diamonds (kimberlitic and impact) are known. The former originated from Phanerozoic kimberlites, and the latter, from astroblemes. For the other types, nonkimberlitic sources are suggested, including Precambrian ones.

This paper presents the results of the first comprehensive geological, petrographic, mineralogical, geochemical, and geochronological studies of ultramafic and mafic magmatism in poorly explored southwestern Tuva by the example of the Birdag and Khayalyg massifs. These massifs break through ortho- and paraschists, which are presumably Middle Proterozoic. Amphibole gabbros in the Khayalyg massif contain numerous relict host-rock xenoliths. The massifs are dominated by meso- and leucocratic amphibole gabbros with minor ultramafic (serpentinous plagioclase harzburgites and plagioclase lherzolites) and transitional (wehrlites, olivine clinopyroxenites, hornblendites, melanocratic olivine gabbronorites) rocks. The serpentinous plagioclase harzburgites and plagioclase lherzolites occur in the amphibole gabbros of the Birdag massif as small lenticular bodies. The latter are interpreted as xenoliths of ultramafic restites of earlier protrusion rather than mafic-melt differentiates. The wehrlites, olivine clinopyroxenites, hornblendites, and melanocratic olivine gabbronorites forming the outer zones of the xenogenic bodies of ultramafic restites are considered hybrid rocks. They resulted from the contact reactions of mafic melts and their fluids with the xenogenic bodies of ultramafic restites, which were feldspathized during this interaction. In gabbros from both massifs, the chondrite-normalized content of MREE and HREE is lower and that of LREE is higher than those in N-MORB. The plagioclase peridotites, wehrlites, and olivine clinopyroxenites forming xenogenic bodies among the amphibole gabbros of the Birdag massif are richer in REE (especially LREE) than the ultramafic restites in ophiolite associations. This is because they were infiltrated by fluids enriched in these elements during their alteration under the influence of later mafic melts. The studies suggest that the Birdag and Khayalyg ultramafic-mafic massifs result from the spatial coexistence of (1) more ancient small protrusions of ultramafic restites, which occurred as allochthons among Middle Proterozoic(?) metamorphic rocks, (2) later gabbroic intrusions (from 494±16 to 450-447.4±5 Ma), and (3) hybrid transitional rocks (wehrlites, olivine clinopyroxenites, hornblendites, melanocratic olivine gabbros) making up contact-reaction zones along their boundaries.

The physicochemical modeling of mineral formation processes at the Badran subthrust gold-quartz deposit was performed, based on a study of fluid inclusions in quartz by Raman spectroscopy, gas chromatography, thermometry, and freezing. The results show that at stage I, highly productive gold-bearing quartz veins (gray quartz) of the deposit formed from heterogeneous fluid at <320 ?C and 2.0-0.1 kbar with the active participation of CO₂, N₂, and CH₄; the salinity of this solution reached 10 wt.% NaCl-equiv. At stage II (Au-productive), milky-white quartz was produced from the homogeneous medium-chloride-sulfide solution which remained after the heterogenization of the initial fluid, at 300-100 ?C and 0.1 kbar. At stage III (with low Au production), clear quartz formed from homogeneous chloride solutions with salinity of <4.5 wt.% NaCl-equiv. at <200 ?C and <0.1 kbar.
The physicochemical conditions of Au concentration within the complex geochemical system Au-Fe-Cu-Pb-Zn-As-Sb-Hg-Ag-H₂O-Cl-H₂S-CO₂ at the Badran deposit was modeled using the Chiller software. The following models were used: (1) solution-rock interaction and (2) condensation of gas phase (for stage I); (3) simple cooling of medium-chloride-sulfide solution (for stage II); (4) simple cooling and (5) mixing of low-chloride-sulfide solution with acid meteoric waters (for stage III). The models show the sequence of vein formation in the ore-producing system and the host-rock metasomatism in the deep horizons of the deposit.

The Bulka layered intrusion, a standard intrusion of the Bulka complex, is localized in northeastern West Sayan. The layered series is composed of dunites, melanotroctolites, troctolites, olivine gabbro, gabbro, hornblende gabbro, olivine leucogabbro, olivine leucogabbronorites, leucogabbro, hornblende leucogabbro, leucotroctolites, anorthosites, and plagioclase-containing hornblendites. The Mg-number (Mg#) varies from 76 in peridotites (38 wt.% MgO) to 34 in anorthosites (2 wt.% MgO). From bottom to top of the section, the following sequence of crystallization of liquidus minerals is observed: Ol ⇒ Pl ⇒ Cpx ⇒ Opx ⇒ Amph + Mag. The petrochemical features of the massif rocks are consistent with the fractional crystallization of picritic parental magma (24 wt.% MgO, 11 wt.% FeO, Mg# = 80). The compositions of model cumulates determined by fractional crystallization modeling using the COMAGMAT 3.5 computer program at 1-2 kbar, QFM buffer, and 0.5 wt.% H₂O in the melt are similar to those of the intrusion rocks. The REE and trace-element patterns for these rocks show a nonfractionated composition trend with LILE and HFSE depletion. Depleted LILE pattern is similar to that in N-MORB, which evidences that the parental magma was produced through the partial melting of oceanic lithospheric mantle probably similar to the adjacent ophiolites of the Kurtushiba belt. The HFSE depletion of the intrusion rocks might be due to the island-arc processes during the belt formation. The Bulka intrusion formed at the accretion-collision stage of magmatism as a result of the differentiation of picritic melt generated from oceanic lithospheric mantle with superposed island-arc processes.

Literature data on mercury contents in natural waters are reviewed. Soils from natural and natural-technogenic landscapes of southern West Siberia are studied, and the solubility of their mercury in water, ammonium acetate, and hydrochloric extracts is determined. The concentrations of mercury from natural soils in water and ammonium extracts (0.045-0.060 ?g/l) are consistent with its calculated approximate average solubility in unpolluted waters reported in literature.
The average content of mercury in extracts from urbanized soils is higher: Its solubility in water extracts is 5.6-5.9 times higher; in ammonium acetate extracts, 3.8-12.4 times; and in hydrochloric extracts, 1.3-1.6 times. The boundary values of mercury solubility in water and ammonium acetate extracts from the studied soils (0.07-0.10 ?g/l) permit revealing technogenic pollution at its early stages.

Data on lacustrine sediments permitted reconstructing climate and vegetation changes in the steppe zone of southeastern Transbaikalia in the Holocene and the evolution of Lake Zun-Soktui. Also, changes in the size of the lake water plane have been reconstructed. A shallow lake formed in place of an oxbow lake in the middle Boreal phase of the Holocene. In the Atlantic phase, the lake had maximum depth and area. In the late Boreal, early Subboreal, and in the second half of the Subatlantic stage, the lake underwent significant shallowing and sometimes dried up for a short time. In the middle Boreal and the Atlantic phases, the aridization decreased considerably. It has been established that pine forest belts on the Onon high plain before the Subatlantic occupied several times more space than now.

Geomagnetic measurements during the total solar eclipse of August 1, 2008 in Novosibirsk (Klyuchi Observatory, NVS) and at the Burmistrovo station located on the total eclipse axis revealed eclipse-induced changes against the background of the normal daily variation. The main changes are a decrease in the X (north) component and an increase in the inclination I . Similar changes were recorded at the LZH observatory in China. Analysis of data on the eclipse of August 11, 1999 in Europe failed to unambiguously reveal eclipse effects against intense variations of ionospheric origin which occurred at the same universal time (UT). The geomagnetic effect of the solar eclipse may be due to a decrease in the electron concentration in the ionosphere and the corresponding decrease in the ionospheric current density.

Mass measurements of joints in Cenozoic sediments from the Baikal rift have yielded statistical data suitable for processing with a new structural-genetic approach. In the course of processing, the new approach has been methodologically completed with formalized techniques for proceeding from local stress tensor reconstructions to regional-scale stress patterns. The jointing patterns in soft sediments of the area have been recognized to be basically of tectonic origin, and their seeming fuzziness to result from spatial and hierarchic variations during rifting-related stress and strain changes. The patterns vary in time, space, and hierarchy, the three kinds of variability being associated, respectively, with stages of rifting and failure dynamics, with control from the prerift tectonics, and with the existence of six hierarchic levels of stress tensors. For the latter, the complete hierarchy of six stress levels has been recognized for the first time in the Pribaikalian crust.

The eruptive behavior of mud volcanoes has been explored in several forward and inversion models. The forward models, based on classical continuum-mechanics, simulate the nonstationary processes of gas seepage and two-phase gas-mud flow through the conduit of a mud volcano, as well as the quasi-stationary gas frontal drive that pushes mud out, and the subsequent gas escape into the air. Forward modeling is performed with reference to the pressure and temperature dependence of the gas viscosity and compressibility. The inversion for the depth to the mud column base has yielded an unambiguous solution. According to the modeling results, the depths to the mud base and to the gas reservoir are controlled mainly by conduit permeability, while the interval between two successive eruption events depends on the gas/mud viscosity ratio. The modeling has allowed estimates for the mud breccia portion remaining in the conduit by the time of eruption, and for the subsurface volcano thickness inferred using a hydraulic-fracture model of the related gryphon field, and for the rate of gas release at the beginning of an eruption.

An estimation algorithm for the trajectory of a mark-making object is developed which does not require interactive selection of the region of marks. An adequate measure of the straightness of marks is proposed which allows quantitative evaluation of the performance of the estimation algorithms. Results of experimental studies are given that support the possibility of using the gradient structure tensor to estimate moving object trajectories from images obtained during motion analysis

A new technical approach to investigation of heterogeneous catalysts with deposited metallic nanoparticles of the active component is suggested. Small-angle X-ray scattering (SAXS) patterns for powder samples of the support matrices with deposited metal particles (Pt, Pd and others) taken at varying density contrast are shown to provide essential information on the structure and dispersity of the active components and their interaction with the support surface, which allows an integral assessment of the formation of strong chemical binding of deposited metal to the support matrix. The measured structural characteristics are compared with data obtained by other physicochemical methods, in particular, transmission electron microscopy (TEM). The suggested technique is verified using mathematical models and applied to a real heterogeneous catalyst Pt/γ-Al₂O₃. The proposed method of SAXS data analysis makes it possible to reveal the formation of active sites in heterogeneous catalysts and optimize their preparation procedures.

The possibility of controlling the state of platinum deposited on the support surface via minor changes in the catalyst preparation procedure is demonstrated using a series of highly dispersed Pt/γ-Al₂O₃ catalysts with different particle size of the active component. Dispersity, local structure and electronic state of supported platinum were examined by a combination of high resolution transmission electron microscopy and X-ray absorption spectroscopy (EXAFS/XANES). It was shown that various platinum species can be obtained on the surface of the support: bulk or surface Pt(II) or Pt(IV) oxides, mixed metal-oxide structures, bulk particles of metallic platinum, and two-dimensional surface Pt⁰ particles strongly interacting with the support.

The potential of modern solid-state NMR spectroscopy techniques applied to quadrupolar nuclei with half-integer spin is demonstrated. Correlations of NMR parameters with the local environment of nucleus (for 14 nuclei) are presented in the second part of the review.

Precision X-ray diffraction at synchrotron radiation was used to reveal the separation of perovskite-like oxides SrCo_0.8-xFe_0.2Nb_xO_3-z (x = 0.2 and 0.3) into two phases of a similar structure identical to initial perovskite structure, but having different unit cell parameters and supposedly different oxygen deficiency. The structural transformation is accompanied by oxygen outlet from the structure. The study of oxygen atoms intercalation from air into the oxygen-deficient structure showed that the structural changes are reversible: heating to 400°C in air restores the initial state of samples.

Fundamental and methodological aspects of secondary ion mass spectrometry applied to analysis of elemental/phase composition and structure of the surface layers of fine materials are discussed.

The charged state of atoms in layered cation-substituted disulfides CuCr_1-xV_xS₂ (x = 0-0.4) was studied using X-ray photoelectron spectroscopy. The study was performed with polycrystalline powder and ceramic samples of chromium-copper disulfides. CuCr_1-xV_xS₂ samples were shown to comprise differently charged atoms of chromium, copper and vanadium, the charged state of which varies with the concentration of vanadium cations (x).

Polyimide films on BK7 glass, which are used to produce matrices for infrared detectors, have been synthesized. When these systems are investigated by monochromatic zero ellipsometry, the least difference between parameters of the incident light polarization, which are determined from suppression angles of polarizer and analyzer and calculated within a certain model, is obtained via introducing air between mounting glass and the film. Validity of the solution was verified by holding the film in water vapor; then, solution of the inverse problem of ellipsometry indicated the appearance of liquid water between the film and mounting glass. Data of the electron microscopy study were used to suggest a water penetration mechanism and develop a physical model of the system polyimide film/mounting glass.

The structure of trans-[RuNO(NH₃)₄(H₂O)](NO₃)₃ (I) and trans-[RuNO(NH₃)₄(NO₃)](NO₃)₂ (II) was determined by XRD. Crystallographic data are as follows: space group I4₁/a; a = b = 18.280(1) Å, c = 15.129(1) Å, R = 0.0244 (I), and space group Cm, a = 11.5620(3) Å, b = 7.9934(2) Å, c = 7.7864(2) Å, β = 127.124(1)°, R = 0.0139 (II). Interatomic distances for complex particles of fac- and mer-[RuNO(NH₃)₂(NO₃)₃] (III and IV, respectively) were determined by EXAFS.

Reverse micelles of oxyethylated nonylphenol (Triton N-42) were used to synthesize ultradispersed powder of ammonium nitrate with the yield 75% and content 79%. Its composition and morphology were examined by colorimetry, IR Fourier spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). According to XRD, the sample is stable with time, although it is a mixture of three polymorphic forms of crystal ammonium nitrate - one stable and three metastable forms. The agglomerates consists of 20-50 nm nanoparticles; a part of nanoparticles form filaments of length 0.5-1.5 μm and thickness 25-30 nm, as estimated by SEM.

Texture characteristics of the oxidized Technosorb carbon material were investigated. The BET surface area, specific surface area of mesopores, mesopore diameter distribution, and total pore volume were determined using an ASAP 2400 adsorption instrument and a Sorbtometer-M analyzer. Changes in the texture characteristics upon oxidation were monitored.

Results obtained by the authors on the development of holographic methods for investigation of photopolymer materials are presented. The work considers the methods for pulse recording of dynamic transmission gratings and characterization of hologram angular selectivity, the double-beam method of two-photon holographic recording, and heterodyne detection of inhomogeneities in volume holograms.

The initial stages of iron film growth on monocrystalline silicon were studied using a combined method of magneto-optic ellipsometry. The growth of iron silicide nanoclusters on the silicon surface was shown to occur at thickness d < 1.2 nm in non-magnetic phase.

Novel multifunctional hybrid nanocomposites with silver and gold nanoparticles stabilized by original polymer matrix based on poly-1-vinyl-1,2,4-triazole were synthesized and studied using UV and IR spectroscopy, X-ray diffraction analysis and transmission electron microscopy. The obtained nanocomposites comprise silver or gold nanoparticles of spherical and elliptical shape with size 3-20 nm and 1-10 nm, respectively.

The study deals with octogen (HMX) and aluminum, which are among the most widely used components of condensed high-energy systems. The structure, thermal behavior and combustion parameters were determined for the octogen-based monofuels and octogen-aluminum binary systems at different dispersity of components. Irrespective of differences in thermal behavior, monofuels obtained with standard and ultrafine octogen powders were shown to have virtually identical combustion parameters. In the binary systems, replacement of standard microsized aluminum by ultrafine one increases the combustion rate by a factor of 2.5, and completeness of the metal reaction (oxidation) by a factor of 4.

The effect of crystallization conditions on the relaxation properties of ultra-thin surface layers in the melt-grown ultra-high molecular weight polyethylene samples was studied using a novel Nanoluminograph device. The device can record thermoluminescence generated upon heating the sample preactivated by high-frequency low-temperature low-power glow-discharge plasma. The glow curves were analyzed, and activation energy of thermoluminescence for the observed glow maxima was calculated. The effect of crystallization conditions on the formation of a lamellar structure on the surface of ultra-high molecular weight polyethylene was examined. The possibility of structural characterization of disordered interlamellar regions using thermoluminescence data is discussed. The estimated activation energy of thermoluminescence was used to calculate the apparent dimensions of kinetic units of motion in the region of β transition, which are supposed to characterize the cooperativeness in the motion of molecular segments.

Experimental conditions of synchronous thermal analysis (STA) for gaining the reliable values of kinetic parameters and constructing a thermokinetic model of octogen decomposition were determined. A decrease in the samples' heating rate in the range of 20-0.5 K/min was shown to diminish the values of activation energy (E_a) and preexponential factor (A). E_a measured at low heating rates (2-0.5 K/min) is close to the energy of N-NO₂ bond cleavage, which is postulated as the first stage of the decomposition. Results of thermokinetic modeling of the octogen thermal decomposition are presented.

A new approach to synthesis of the ordered germanium nanorod arrays using thermal sputtering on the matrices of porous alumina with the ordered channel arrangement is presented. The synthesized filamentary nanostructures were examined by scanning electron microscopy (SEM), EXAFS and XANES spectroscopy. Data on nanorod geometry in arrays, parameters of the local atomic structure such as interatomic distances and coordination numbers for initial samples and those annealed at 450°C in the argon atmosphere, and data on changes in the electronic states near the absorption K-edge were acquired. A comparison was made with the data of EXAFS studies of a continuous Ge film synthesized on a smooth surface of non-porous Al₂O₃.

A microcapsulated material containing dibenzo-18-crown-6 (DB18C6) or 18-crown-6 (18-C6) as an extractant was synthesized. IR spectroscopy was used to investigate the state of encapsulated crown ether and the mechanism of Sc³⁺ extraction from a sulfate solution, which proceeds via the formation of a "host-guest" complex with inclusion of a metal ion into the macrocycle hole. The electron microscopy examination revealed the effect of solvent addition during the synthesis and the crown ether composition on the morphology of synthesized samples.

Electron and chemical ionization mass spectrometry and MALDI were used to investigate a medicinal preparation, calcium gluconate (CG), and its more active mechanoactivated form (MACG). Admixtures in CG were identified. Mechanoactivation was shown to produce no new compounds. The enhancement of medicinal activity of MACG may be related with its conformational transition.

The phase composition, surface morphology and crystalline structure of carbon-containing silicon layers grown on silicon plates of various orientation by vacuum gas phase epitaxy using different operating conditions are considered. The possibility of phase transition from a Si_1-xC_x solid solution to silicon carbide upon annealing of the structures obtained by low-temperature epitaxy is discussed. The films were examined by the electron, probe and interference optical microscopy, electron diffractometry, and X-ray diffraction methods. The effect of germanium intercalated in a film during its growth on the surface morphology and crystalline structure of carbon-containing silicon layers is examined. Irrespective of the method of germanium insertion in the growing film, a maximum Ge concentration is attained at the interface of silicon and 3C-SiC layers. A comparative study of the surface roughness of 3C-SiC films grown on Si(100) was performed upon variation of the temperature and germanium content in a mixture of gases. The interference optical microscopy was used to investigate the surface morphology of heteroepitaxial structures 3С-SiC/Si in comparison with the surface characteristics of buffer structures based on Si and Ge. The 3C-SiC layers grown on Si(100) and Si(110) were shown to have quite a low surface roughness, which is comparable with the characteristics of Si_1-хGe_х/Si(100) layers and СР(Ge-Si_1-хGe_х)/Si(100) superlattices at the initial roughness of Si underlayers ~1-2 nm.

Principles of the stoichiography and differential dissolution method (DD) providing deep insight into the composition of mixtures containing unknown chemical compounds are considered. Compounds can be identified using their primary feature - the stoichiometry of elemental composition; reference samples of the compounds are not needed. The DD method makes it possible to analyze mixtures of crystalline and/or amorphous phases with constant and/or variable composition in the form of dispersed powders, ceramics, crystals, thin films and nanosize objects. Various aspects of the stoichiography and DD method application to investigation of composition, structure and properties of the functional materials are discussed.

The possibilities of gas chromatography for determination of physicochemical properties of the surface are demonstrated. Changes in the surface properties of poly(1-trimethylsilyl-1-propyne) (PTMSP) with time were investigated. It was found that with the lapse of time the sorption-desorption processes proceed mainly in mesopores due to decreasing the polymer micropore volume. The formation of a chemically more uniform surface strongly increases the symmetry of chromatographic peaks and the column efficiency.

A method for preparation of divinylbenzene-styrene copolymer porous layer on the inner wall of a fused silica capillary was developed. Capillary gas chromatography was used to investigate the sorption capacity of copolymer film toward substances of various classes.

Solid state voltammetry was used for phase analysis of the natural oxide films on A^IIIB^V semiconductors. Such films, both anodic and thermal, were shown to be inhomogeneous mixtures of various phases and their structural modifications. Unstable state of the natural oxide layers on A^IIIB^V semiconductors was caused by their surface oxidation leading to the formation of nonequilibrium set of phases, their amorphous and unstable crystalline forms. A technique for express identification of superconducting phases and their characteristics was developed. All electrochemical characteristics of the detected signal indicate the presence of oxygen in superconducting phases, which is able to accept electrons and thus provide electroneutrality of the molecule.

An optimized and unified technique for CHN analysis of functional materials was suggested to enhance the accuracy of results due to increasing the completeness of sample combustion and improving the resolution of C and N peaks. The obtained contents of carbon, nitrogen and hydrogen agree well with the calculated values and are supported in most cases by structural studies.

Specific features of elemental composition analysis of silicon carbonitride thin films by energy dispersive spectroscopy (EDS) are considered. The films were preliminarily examined by IR spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron (SEM) and atomic force microscopy (AFM), and X-ray diffraction analysis using synchrotron radiation (SR-XRD) to acquire data on their chemical and phase composition, crystalline structure and surface morphology. The effect of film thickness, substrate material and electron beam energy on the results of energy dispersive analysis was investigated.

A set of specially selected classic and automated elemental analysis techniques was used to determine with a required accuracy the composition (C, H, N, Cl, Br, F, Ti, Fe) of transition metal complexes employed in post-metallocene catalytic systems. The element determination was in error by ±0.3-0.5 abs.%. Molecular weights of the synthesized oligomeric ligands were measured within the accuracy of 0.2-2.6 rel.% using the vapor-phase osmometry.

A unified technique was developed for chemical atomic-emission analysis of high-purity germanium(IV), molybdenum(VI), tellurium(IV) and tungsten(VI) oxides based on preliminary concentration of non-volatile impurities by distilling off the matrices after chemical transformations into volatile fluorides by xenon difluoride vapor in an autoclave. The impurity concentrate was analyzed by atomic-emission method with arc and induction discharges. The detection limits of impurities in a gram analytical sample were found to be 10^-6-10^-8 wt.%.

A technique has been developed for analysis of impurities in precursors of the optic ceramics: aluminum isopropoxide, yttrium and neodium oxide nanopowders (weight fraction of Nd ≤5%) by atomic-emission spectroscopy with inductively coupled plasma. In the case of aluminum isopropoxide, the effect of matrix is compensated by applying Bi as an internal standard. The detection limits of impurities were found to be10^-5-10^-6 wt.%.

A method for estimation of the phase composition of electrolytic deposits using voltammetric curves of their electrooxidation was developed. A formula for calculating the potential displacement in the case of selective electrooxidation of electronegative component of an alloy was suggested. If variation in the molar fraction of the alloy component does not affect the potentials of additional anodic peaks, this results in the formation of electrolytic deposit with intermetallic compounds on the electrode. If potential of additional anodic peak changes with variation in the molar fraction of the alloy component, a deposit forming on the electrode is represented by a solid solution. Displacement of the anodic peak potential of electronegative alloy component toward "solid solution" can be used to calculate a molar fraction of the alloy component, i.e., to solve the inverse problem.