34 research outputs found

    Close Packing of Atoms, Geometric Frustration and the Formation of Heterogeneous States in Crystals

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    To describe structural peculiarities in inhomogeneous media caused by the tendency to the close packing of atoms a formalism based on the using of the Riemann geometry methods (which were successfully applied lately to the description of structures of quasicrystals and glasses) is developed. Basing on this formalism we find in particular the criterion of stability of precipitates of the Frank-Kasper phases in metallic systems. The nature of the ''rhenium effect'' in W-Re alloys is discussed.Comment: 14 pages, RevTex, 2 PostScript figure

    Synthesis of TiO2 and F-doping TiO2 powders via "reverse" hydrolysis of titanium tetraisopropoxide

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    TiO2 and F-TiO2 powders were prepared by hydrolysis of titanium tetraisopropoxide with reversed mixing of different hydrolytic reagents. The typeof the hydrolytic agentstronglyinfluences particle size, morphology and phase composition ofpowder.It was found, that the amount of injected water is significantly affects on BET surface area and particle size ofbare TiO2.The presence offluorinemakes the samplemore porous and preventsanatase to rutile phase transformation under prolonged heat treatment, also particle formed are bigger in comparison with un-doped TiO2

    Synthesis of TiO2 and F-doping TiO2 powders via "reverse" hydrolysis of titanium tetraisopropoxide

    No full text
    TiO2 and F-TiO2 powders were prepared by hydrolysis of titanium tetraisopropoxide with reversed mixing of different hydrolytic reagents. The typeof the hydrolytic agentstronglyinfluences particle size, morphology and phase composition ofpowder.It was found, that the amount of injected water is significantly affects on BET surface area and particle size ofbare TiO2.The presence offluorinemakes the samplemore porous and preventsanatase to rutile phase transformation under prolonged heat treatment, also particle formed are bigger in comparison with un-doped TiO2
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