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  • 1
    Electronic Resource
    Electronic Resource
    Computer models for electrical conductivity of multicomponent solid-state systems (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 1782-1787 
    Details
    ISSN: 1573-9171
    Keywords: composite ; electrical conductivity ; percolation ; intergranular barriers ; Monte-Carlo simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Models for the computer simulation of electrical conductivity of polycrystalline materials and mixtures are proposed. The effect of model parameters on the concentration behavior of conductivity is considered. The correspondence between the model parameters and the characteristics of physical objects is established, thus making it possible to analyze the spatial relations in solid-state systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00698987
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  • 2
    Electronic Resource
    Electronic Resource
    Analysis of electric conductivity of binary solid-state catalysts by computer simulation (1993)
    Springer
    Russian chemical bulletin 42 (1993), S. 1788-1791 
    Details
    ISSN: 1573-9171
    Keywords: electric conductivity ; mechanical mixtures ; Monte-Carlo simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Experimental and model studies of concentration dependencies of electric conductivity have been performed for a number of binary mechanical mixtures. The physical origins of various peculiarities are discussed with Fe3O4+MgO, Fe3O4+NiO, and Ni+ZrO2 systems considered as examples. The degree of friability of the systems and the degree of homogeneity of the component distribution are estimated. A considerable mutual influence of the phases is observed, which is, however, not a chemical interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00698988
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  • 3
    Electronic Resource
    Electronic Resource
    Surface phase analysis of catalysts and other disperse materials using electroconductivity: The TVE-curves method (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 257-283 
    Details
    ISSN: 1573-9171
    Keywords: methods for the investigation of catalysts ; electroconductivity of disperse materials ; the surface of semiconductors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The method of thermovacuum electroconductivity (TVE) curves for the analysis of surface phases in disperse systems is described. The theoretical basis of the application of electric measurements for the investigation of the surface of disperse objects is presented. Examples of the use of the TVE-curves method for characterization of diverse catalytic systems and the solving of some problems of heterogeneous catalysis are discussed. The TVE-curves method is an efficient tool for the control of the phase-structural state of the surfaces of objects of a semiconductor type.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01433957
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  • 4
    Electronic Resource
    Electronic Resource
    Theoretical description of pores in the simulation of composite materials (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 1279-1283 
    Details
    ISSN: 1573-9171
    Keywords: Monte Carlo simulation ; electric conductivity ; dielectric constant ; porosity ; barrier-disordered systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The influence of porosity on the electric conductivity and the dielectric constants of composite materials was studied using computer simulation (the Monte Carlo method). A new approach to the simulation of porous systems that treats pores as a component equivalent to the solid phase components was proposed. Within the framework of this approach, an analysis of the influence of the micro- and macroporosity on the electric conductivity was carried out. It was established that the concept of a barrier-disordered system is also valid for pores. It was shown for the first time that pores can serve as one of the factors that forms the contact barrier distribution function. The proposed theoretical models were in good agreement with the experimental data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01434196
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  • 5
    Electronic Resource
    Electronic Resource
    Preparation and properties of coprecipitated catalysts of NiO-TiO2 system (1974)
    Springer
    Russian chemical bulletin 23 (1974), S. 1568-1570 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. A method was developed for the preparation of coprecipitated catalysts of the NiO-TiO2 system, which made it possible to prepare samples with a large value of the specific surface and practically devoid of Fe and Cl impurities. 2. Based on an analysis of the results of a complex study of the system by many physical methods it was concluded that the structure characteristics and properties of these catalysts are caused by reaction between the components of the system, which takes place even during the precipitation step. 3. A possible, mechanism for the deactivation of coprecipitated catalysts was discovered, which consists in the formation of surface layers of the inactive reaction product of the components (NiTiO3), which shield the active phase (NiO).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00929687
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  • 6
    Electronic Resource
    Electronic Resource
    Surface solid-state interactions in copper-nickel-cement catalysts for hydrogenation of oxygen (1994)
    Springer
    Russian chemical bulletin 43 (1994), S. 1471-1474 
    Details
    ISSN: 1573-9171
    Keywords: copper-nickel-cement catalysts ; surface phase analysis ; electric conductivity ; solid-state interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The surface phase composition of alumocalcium cement-supported CuO and CuO-NiO catalysts prepared by chemical mixing has been studied using the method of thermo-vacuum curves of electric conductivity. The deactivation of these catalysts due to overheating to 800 °C under conditions of hydrogenation of oxygen is rationalized by the partial extraction of CuO (and NiO) from the stabilizing structure of the support solid solutions and by sintering of the extracted oxides and the reduced metallic phase. Complete regeneration of the CuO-NiO-talum catalysts can be achieved if a considerable amount (20%) of copper hydroxocarbonate is added.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00697129
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  • 7
    Electronic Resource
    Electronic Resource
    Computer simulation analysis of conductivity of supported polydisperse systems (1995)
    Springer
    Russian chemical bulletin 44 (1995), S. 1391-1395 
    Details
    ISSN: 1573-9171
    Keywords: Monte Carlo simulation ; percolation conductivity ; supported polydispersed system ; surface texture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Effects of the support texture and the supported phase distribution on the conductivity of an individual grain or a granulated system have been analyzed theoretically. Experimental criteria are discussed, which allow one to judge the porous structure and sites of localization of a conducting component on the basis of the concentration dependence of the conductivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00714415
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  • 8
    Electronic Resource
    Electronic Resource
    Physicochemical properties and activity of NiO-MgO catalysts (1976)
    Springer
    Russian chemical bulletin 25 (1976), S. 251-256 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. The authors describe a procedure for obtaining catalysts of the system NiO-MgO (0–100% NiO) by coprecipitating the hydroxides with ammonia; it ensures preparation of specimens with any ratio of the components at the same pH. 2. In the coprecipitated system NiO-MgO there are formed two series of solid solutions with close lattice constants, so that the observed averaging of the value of the constant of the system corresponds to formation of a continuous series of solid solutions. 3. The composition dependence of the dispersion is due to mutual screening of the components against aggregation; this effect is due to the phase-structural characteristics of the coprecipitated system and becomes weaker as the structure becomes more ordered with an increase in the heat-treatment temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00922451
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  • 9
    Electronic Resource
    Electronic Resource
    Physicochemical properties and activity of Nio-Mgo catalysts (1984)
    Springer
    Russian chemical bulletin 33 (1984), S. 900-906 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. In solid substitution solutions in the NiC-MgO system, obtained by coprecipitation of the hydroxides, the nickel is distributed nonuniformly, both because of enrichment of the surface layers in particles of the magnesium oxide component (“macroheterogeneity”) and because of clustering of the nickel(II) oxide (“microheterogeneity”). 2. The macroheterogeneity of the system decreases with increasing temperature of preliminary calcination; at 1100°, the content of nickel on the surface is the same as that in the bulk. 3. Nickel(II) oxide clusters of two types have been identified: small clusters (solid solution of NiO in MgO matrix with weak interaction between nickel ions) and large clusters (nucleated crystals of NiO in the structure of a solid solution of MgO in NiO).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01141692
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  • 10
    Electronic Resource
    Electronic Resource
    Phase analysis of the surface of supported copper-cobalt oxide catalysts by means of electrical conductivity thermal-vacuum curves (1987)
    Springer
    Russian chemical bulletin 36 (1987), S. 1594-1597 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusions 1. Using the method of thermovacuum curves of electrical conductivity it has been shown that in copper-cobalt oxide catalysts supported on talyum obtained from the hydroxycarbonates of the metals in the presence of ammonia water and calcined at 400°C, a solid solution of CuO and Co3O4 forms, i.e., a copper cobaltite of variable composition with the spinel structure. 2. The support facilitates the interaction between the oxides and stabilizes the surface copper cobaltite observed to form at CuO contents as low as ∼5% at ∼200°C. 3. The copper oxide has a tendency to concentrate at the surface of the particles, which should lead to the enrichment of the surface in copper cobaltite compared to the interior of the catalyst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00960111
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