Nanocomposites based on thermoplastic elastomers with functional basis of nano titanium dioxide

Nanocomposites based on a thermoplastic elastomer (TPE) (low-density polyethylene (LDPE) and 1,2-polybutadiene in a ratio of 60/40) with functional titanium dioxide nanoparticles of different nature, TiO₂/TPE, have been prepared and investigated by a complex of methods (X-ray diffraction analysis using X-ray and synchrotron radiation beams, scanning electron microscopy, transmission electron microscopy, and X-ray energy-dispersive spectroscopy). The morphology of the composites is found to be somewhat different, depending on the TiO₂ characteristics. It is revealed that nanocomposites with cellular or porous structures containing nano-TiO₂ aggregates with a large specific surface and large sizes of crystallites and nanoparticles exhibit the best deformation?strength and fatigue properties and stability to the effect of active media under conditions of ozone and vapor?air aging.     

Peculiarities of the microstructure of a nanoscale modification of η-TiO2

Samples with nanoscale η-TiO₂ phase have been obtained by sulfate and modified sulfate methods and are characterized by a complex of techniques: X-ray diffraction, electron diffraction, small-angle X-ray scattering (SAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy, and X-ray energy-dispersive analysis. The effect of sample formation conditions on the size and shape of crystallites, content of the amorphous component in the samples, and their elemental composition has been established. A significant change (depending on the synthesis conditions) in the parameters of the diffraction reflection with d ～ 17–21 Å (intensity and interplanar spacing d, Å), pronounced for η-TiO₂, is revealed. This change is most likely related to the variation in the content of water molecules in the interlayer space of η-TiO₂ structure and/or the change in crystallite shape.     

Unusually high efficiency of the separation of polymers by hydrodynamic chromatography on hollow capillary columns

A series of polystyrene standards was separated by means of hydrodynamic chromatography on a open capillary with a length of 5 m (active zone is 4.5 m) and an inner diameter of 2 μm. Unusually high efficiency in the separation of polymers with masses of up to 500 kDa was noticed: 1.5 × 10⁶ theoretical plates at a retention time of ～70 min for a sample of polystyrene with a mass of 390 kDa. It was established that the column efficiency decreases rapidly for polymers with a mass above 500 kDa. A calibration curve for polystyrene standards was constructed. It was shown that, in contrast to the models described in the literature, it is described by a simple two-term expression without quadratic terms. It is concluded that hydrodynamic chromatography is a technique complementary to exclusion chromatography, especially in the separation of high-molecular polymers.     

Microstructural Features of Poly(N-Vinylpyrrolidone)−La(NO3)3 ⋅ 6H2O Hydrogel

Crystallography Reports - The structural features of the poly(N-vinylpyrrolidone)–La(NO3)3 ? 6H2O composite hydrogel were studied by scanning and transmission electron microscopy. The...     

Crystallization and properties of CrSi2 single crystals grown from a tin solution-melt

Using the solution-melt method combined with the Bridgman method, CrSi₂ single-crystal needles and single-crystal tubes are grown at a temperature lower than their melting (crystallization) temperature. Microcrystals thus grown feature an anomalously high thermal emf. The growth of CrSi₂ single-crystal tubes is an important step forward in the production of various devices based on high-temperature thermoelectric materials.     

On the growth of higher manganese silicide films on silicon

The growth of manganese silicide films on silicon under the conditions of equilibrium and non-equilibrium diffusion doping of the silicon from the vapor phase is studied for different weight percent of the dopant.     

75LiF + 25SmF3 Eutectic Composite and Ionic Conductivity of SmF3 near the Polymorphic α–β Transition

Crystallography Reports - 75 mol % LiF + 25 mol % SmF3 eutectic composite is obtained by fusing components in a CF4 atmosphere. The composite is multiphase and consists of β-SmF3 (sp. gr....     

Ge dots on Si (1 1 1) and (1 0 0) surfaces with SiO2 coverage: Raman study

Germanium quantum dots formed on Si (1 1 1) and (1 0 0)-oriented surfaces coated with ultra-thin oxide layers are studied using Raman spectroscopy technique. Some structural properties (height, stoichiometry and mechanical stresses) of the dots were estimated from Raman data. For analysis of the experimental data, the Raman spectra of Ge nanoclusters containing some hundreds of Ge atoms were calculated numerically. The effects of the resonance enhancement of the intensity of Raman scattering in the Ge-nanoclusters–SiO₂–Si system were discussed. The influence of the lateral sizes of Ge nano-clusters on the frequencies of phonons localized in them was studied using numerical simulation. The influence of multi-layer growth on the structure of the Ge quantum dots was investigated.