M. F. Churbanov

Nizhny Novgorod State University, Gorkey, Nizjnij Novgorod, Russia

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Publications (137)135.85 Total impact

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    ABSTRACT: Precipitates of tellurium(IV), molybdenum(VI), and bismuth(III) compounds of controlled composition have been obtained by precipitation from hydrochloric acid solutions of tellurium dioxide, ammonium heptamolybdate, and dibismuth trioxide. We have examined the general aspects of the macrocomponent distribution between the precipitate and solution and found conditions of a sufficiently complete tellurium(IV), molybdenum(VI), and bismuth(III) precipitation in a weakly acidic medium. After drying and calcination, the precipitates thus obtained were used as starting mixtures for the preparation of TeO2-MoO3-Bi2O3 glasses.
    Inorganic Materials 03/2015; 51(3):241-244. DOI:10.1134/S0020168515030152 · 0.51 Impact Factor
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    ABSTRACT: We have prepared (TeO2)0.80(MoO3)0.20 tellurite glass samples containing 0.02-0.5 wt % nickel and investigated their optical transmission in the range 450-2800 nm. The transmission spectra of the glasses contain absorption bands centered at 810 and 1320 nm. From the composition dependence of the absorption coefficient, we have evaluated the specific absorption coefficient of Ni2+ in the range 600-2800 nm. It has been found to be 20.6 ± 0.4 cm−1/wt % at the maximum of the 1320-nm absorption band.
    Inorganic Materials 03/2015; 51(3):278-282. DOI:10.1134/S0020168515030188 · 0.51 Impact Factor
  • V. S. Shiryaev, M. F. Churbanov
    ChemInform 02/2015; 46(6). DOI:10.1002/chin.201506263
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    ABSTRACT: Glass samples of the GeS2-GeI4 system with iodine content of 5, 8, 10, 12 and 15 at.% are prepared by reacting germanium tetraiodide, germanium and sulfur in the evacuated silica-glass ampoules. The glass samples are characterized by high transparency in the spectral range of 0.55-10 μm. Regularities of changes in optical and thermal properties of the glasses depending on the iodine content are established. Transmission edges of samples are determined and impurity absorption bands are identified. The optimal iodine content in the Ge-S-I glasses for optical applications is determined to be equal to 10-12 at.%. Temperatures of glass transition, the onset of crystallization and starting of weight reduction of samples are determined. Chemical and phase compositions of the products of glass crystallization when heated up to 650 °C are investigated.
    Optical Materials 02/2015; DOI:10.1016/j.optmat.2014.12.048 · 2.08 Impact Factor
  • L. A. Ketkova, M. F. Churbanov
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    ABSTRACT: This paper describes a 3D laser ultramicroscopy technique and apparatus for the nondestructive characterization of heterophase inclusions in bulk high-purity materials for fiber and power optics. In this technique, the concentration and size of inclusions undetectable by optical microscopy are determined using CCD detection of the light scattered by them in a direction normal to the incident laser beam at wavelengths from 0.63 to 0.98 μm. The detection limit of the technique in terms of inclusion size is n × (10–100) nm, the range of detectable number concentrations is 1–1011 cm−3, and the scan depth in the sample is ∼1 cm. Its performance has been evaluated using test systems. The potential of the technique is illustrated by the dispersion analysis of promising materials for IR fiber-optic applications.
    Inorganic Materials 12/2014; 50(12). DOI:10.1134/S0020168514120097 · 0.51 Impact Factor
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    ABSTRACT: Glass samples of the Ge–Sb–Se–I system were prepared by reacting germanium tetraiodide and antimony triiodide with selenium in a set-up which provides selective removal of iodine from the melt. Thermodynamic modeling of purification reactions of the components is shown. The glasses are analyzed by X-ray spectral microanalysis, differential scanning calorimetry, IR spectroscopy, Raman scattering spectroscopy, and laser mass spectrometry. In the purest examples of these glasses, the content of residual impurities is: hydrogen—0.1 ppm mol, silicon—0.02 ppm wt., and transition metals—less than 0.5 ppm wt.
    Journal of Non-Crystalline Solids 11/2014; 405:100–103. DOI:10.1016/j.jnoncrysol.2014.09.015 · 1.72 Impact Factor
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    V. S. Shiryaev, S. V. Mishinov, M. F. Churbanov
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    ABSTRACT: Adhesion between As2S3 glass and quartz glass has been studied by a uniform pull-off method. The pull-off stress for the adhesion of glassy As2S3 to quartz glass has been determined as a function of temperature in the temperature range 110–190°C. The results demonstrate that, in the case of As2S3 glass, the adhesion strength increases exponentially with increasing test temperature and exceeds 2500 kPa at the glass transition temperature. We have studied how the adhesion strength is influenced by the contact temperature and time, tension test temperature, and quartz glass surface roughness.
    Inorganic Materials 11/2014; 50(11). DOI:10.1134/S0020168514110181 · 0.51 Impact Factor
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    V. S. Shiryaev, S.V. Mishinov, M.F. Churbanov
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    ABSTRACT: Adhesion of As40S60, Ge10As22Se68, As30Se50Te20, As40S30Se30, As38Sb2Se30Te30, As30Se70, As35Se65, As37.5Se62.5 and As40Se60 glasses to silica glass is studied by the steady detachment method in the temperature range of 80–210 °C. The separation tension of the studied chalcogenide glasses from silica-glass substrate increases with temperature exponentially and has the maximum with the value of 2000–2600 kPa at temperatures close to Tg. The value of adhesion is shown to depend on the temperature, the surface roughness of silica glass, the chalcogenide glass composition, and the time of formation of adhesive contact.
    Journal of Non-Crystalline Solids 10/2014; DOI:10.1016/j.jnoncrysol.2014.10.010 · 1.72 Impact Factor
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    ABSTRACT: For the first time, the preforms for drawing negative curvature hollow core fibers (NCHCF) based on As2S3 glass, promising to achieve ultra low optical losses and expansion of transmission range in the mid -infrared, have been manufactured. The theoretical minimum optical losses in proposed ideal NCHCFs are estimated to be lower than 1 dB/km. The temperature dependence of work of adhesion of As2S3 glass to silica glass was investigated, as well as the optimal temperature conditions for obtaining preforms were determined. The fiber preforms were manufactured by the “stack and draw” technique from substrate tubes and 8 or 10 capillaries with a designated geometry and thickness of the walls, arranged in a specific configuration for hollow core photonic crystal structure. Substrate tubes were obtained by centrifugal casting, and capillaries were fabricated by melt extraction from a double crucible.
    Journal of Optoelectronics and Advanced Materials 09/2014; · 0.56 Impact Factor
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    ABSTRACT: This paper describes a process for the preparation of extrapure gallium(III) sulfide by reacting gallium(III) iodide with sulfur in an evacuated two-zone quartz glass reactor. The maximum synthesis temperature was 350°C. The residual iodine was removed by calcining the powders at temperatures from 500 to 650°C. The gallium(III) sulfide yield was 93–96% of theoretical yield. The samples were characterized by X-ray microanalysis, X-ray diffraction, and laser mass spectrometry and were shown to contain the following impurities (ppm): silicon, 20–28; iron and calcium, 0.5–0.6; potassium, 0.3–0.7; chromium, 0.2; chlorine, 70–100; aluminum, 0.05–0.1; and phosphorus, 0.1–2. The iodine content varied from 0.04 to 1.8 at %, depending on calcination temperature and time.
    Inorganic Materials 07/2014; 50(7):656-660. DOI:10.1134/S0020168514070152 · 0.51 Impact Factor
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    ABSTRACT: Small additions of Ga to Ge–As–Se glasses are known to enhance rare earth ion solubility in Ge–As–Se chalcogenide glasses designed for active optical applications. The effect of variants and conditions for producing samples of an exemplar Ge16As17Se64Ga3 (atomic%) glass on optical transmission, and the content of limiting impurities, is investigated. To prepare the high-purity glass samples, chemical distillation for purification of the Ge–As–Se base-glass is used. Next, a new vapor phase transport approach of metallic Ga transfer in a GaI3 flow is developed to purify and add the batch of metallic gallium into the silica-glass reactor for the Ge–As–Se–Ga glass synthesis. A thermodynamic equilibrium based vapor phase transport model is discussed. In the best examples of these glasses, the content of residual impurities is: hydrogen – 0.15 ppm, oxygen – <1 ppm, and transition metals – less than 0.1 ppm.
    Optical Materials 05/2014; DOI:10.1016/j.optmat.2014.04.021 · 2.08 Impact Factor
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    ABSTRACT: The process of hydrogen reduction of 32S from 32SF6 via RF capacitive plasma discharge was investigated at low pressure. The main products of the plasma-chemical reactions were identified by mass-spectrometry and IR-spectroscopy techniques. The dependence of 32S yield on energy contribution was studied at two molar ratios of the initial substances H2: 32SF6. The optimum conditions for the process of plasma-chemical reduction were determined in terms of the maximum conversion degree of 32SF6 into 32S which attained 70%.
    Journal of Fluorine Chemistry 04/2014; 160. DOI:10.1016/j.jfluchem.2014.01.011 · 1.95 Impact Factor
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    ABSTRACT: We presented the results on the preparation of high-purity monoisotopic varieties of silicon and germanium. The process involves the separation of isotopes in the form of SiF4 and GeH4 by centrifugation, ultrapurification of volatile compounds, and preparation of poly and single crystals. The attained degree of isotopic and chemical purities of single crystals obtained was shown. The content of the main isotope in the single crystals of 28Si is >99.99% and those in the single crystals of 29Si and 30Si are >99.9%. The specific resistivity of the 28Si single crystals is ∼1 kOhm cm and those of 29Si and 30Si are about 100–150 Ohm cm. The samples of the 76Ge single crystals have the main isotope content of >88 at.% and the difference concentration of electrochemically active impurities of 5·1010 cm−3. The main isotope content in the 74Ge polycrystal is 99.93 at.%. The optical and thermophysical properties of the isotope-enriched silicon and germanium single crystals were measured, which suggest a significant effect of the isopotic composition on thermal capacity, thermal conductivity, luminiscence, and light absorption.
    ChemInform 03/2014; 45(12). DOI:10.1002/chin.201412279
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    ABSTRACT: Experimental and theoretical studies of spectral properties of chalcogenide Ge–S and As–Ge–S glasses and fibers are performed. A broad infrared (IR) luminescence band which covers the 1.2 – 2.3 μm range with a lifetime about 6 μs is discovered. Similar luminescence is also present in optical fibers drawn from these glasses. Arsenic addition to Ge–S glass significantly enhances both its resistance to crystallization and the intensity of the luminescence. Computer modeling of Bi-related centers shows that interstitial Bi+ ions adjacent to negatively charged S vacancies are most likely responsible for the IR luminescence.
    Optical Materials Express 02/2014; 4(2-2):366-374. DOI:10.1364/OME.4.000366 · 2.92 Impact Factor
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    ABSTRACT: Homogeneous oxidation of hydrogen selenide with ozone present in deficiency was studied. One of the reaction products is elemental selenium Se8, which can be formed by multistep radical-chain polycondensation of hydrogen selenide. One mole of ozone is consumed per mole of hydrogen selenide. The observed rate constant of the reaction of hydrogen selenide with ozone at 20 ± 1°C is no less than (1.9 ± 0.2) × 105 l mol−1 s−1.
    Russian Journal of Applied Chemistry 12/2013; 85(12). DOI:10.1134/S107042721212021X · 0.29 Impact Factor
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    ABSTRACT: Te rich glasses in the ternary Ge-Te-Se system are stable against crystallization and remain transparent enough for application in the far infrared beyond 15 μm. Four protocoles of preparation of highly-purified Te-rich Ge-Te-Se glasses are developed and compared. These methods are based on different distillation procedures to remove water, oxides, hydrogen and carbon impurities from glasses. The final residual impurity content in glasses was determined by the IR spectroscopy and laser mass spectrometry. Then, unclad optical fibers were drawn from each synthetized glass. At room temperature, the minimum of attenuation is about 7 dB/m at 10.6 μm whatever the purification procedure, showing that the residual optical losses are intrinsic to the chemical nature of the glasses. On the other hand, at 77 K, the optical losses are lowered to 1 dB/m confirming that losses are mainly due to the high charge carrier concentration inherent to the semi-conducting behavior of these glasses. Finally, this low level of losses is rather a promising news in view of application in space where optical filtering devices working beyond 15 μm are needed.
    Journal of Lightwave Technology 06/2013; 31(11):1703-1707. DOI:10.1109/JLT.2013.2257163 · 2.86 Impact Factor
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    ABSTRACT: The method for the preparation of high purity Ge-Te-AgI glasses with low content of the limiting impurities has been developed. The method includes the synthesis of GeTe4 glass using chemical distillation purification, loading AgI and GeTe4 into silica glass reactor by evaporation in all-sealed glass vacuumed system, melting the (GeTe4)(100 - x)(AgI)(x) (x = 0-20) glass,into muffle rocking furnace at 850 degrees C, quenching the glass in water with subsequent annealing and cooling. The prepared glass samples were investigated by energy-dispersive X-ray microanalysis, DSC, FTIR-spectroscopy, Raman spectroscopy, and laser calorimetry. The high purity (GeTe4)(100 - x)(AgI)(x) (x = 0-20) glass samples are characterized by good transparency in the spectral range of 2-20 mu m, glass transition temperature of 140-160 degrees C. T-c - T-g difference of more than 100 degrees C, and a very low content of the limiting impurities. Some glass compositions with AgI content between 10 and 20 at.% manifest a good thermal stability against crystallization.
    Journal of Non-Crystalline Solids 05/2013; 377. DOI:10.1016/j.jnoncrysol.2013.03.039 · 1.72 Impact Factor
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    ABSTRACT: We have assessed interlaboratory and between-method discrepancies in the certification of standards of high-purity nanomaterials and precursors and analyzed the dependence of the discrepancy on the impurity concentration (an important factor, influencing the discrepancy value) and analytical method.
    Inorganic Materials 04/2013; 49(4). DOI:10.1134/S0020168513030102 · 0.51 Impact Factor
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    ABSTRACT: We have studied novel materials promising for fiber-optic applications: composites in the form of As2S3 glass containing Cr2+-doped zinc chalcogenide particles. Their dispersion characteristics and optical properties have been investigated in relation to preparation conditions. Process parameters have been found that enable the fabrication of optical fibers possessing luminescence properties.
    Inorganic Materials 03/2013; 49(3). DOI:10.1134/S0020168513030072 · 0.51 Impact Factor
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    ABSTRACT: Molybdate-tellurite glasses have been prepared from precipitates obtained by adding aqueous ammonia to hydrochloric acid solutions of tellurium(IV) and molybdenum(VI) compounds. The impurity compositions of the precipitates and glasses have been determined by atomic emission spectroscopy. The results indicate that contamination with metal impurities occurs mainly in the precipitate washing step. Prolonged holding of a glass-forming melt in a porcelain crucible leads to contamination of the glass with aluminum, magnesium, and calcium.
    Inorganic Materials 02/2013; 49(2). DOI:10.1134/S0020168513020210 · 0.51 Impact Factor