The effects of high-voltage pulse electric discharges on ion adsorption on activated carbons

The effects of high-voltage pulse electric discharges (HPED) on sorption of boron and sulfate ions on activated carbons of different kinds (KM-2, BAU, DAK) were investigated. The effect of HPED activation on the sorption characteristics of the systems was found to be similar to the temperature effect.     

Crystal structures of dioxonium hexafluorotantalate and dioxonium hexafluoroniobate complexes with tetrabenzo-30-crown-10

Two isostructural complexes of dioxonium [H₅O₂]⁺ with tetrabenzo-30-crown-10 of the compositions [(tetrabenzo-30-crown-10 · H₅O₂)][TaF₆] (I) and [(tetrabenzo-30-crown-10 · H₅O₂)][NbF₆] (II) are studied using X-ray diffraction. The complexes crystallize in the monoclinic crystal system (space group C2/c, Z = 4). The unit cell parameters of these compounds are as follows: a = 15.6583(12) Å, b = 15.2259(13) Å, c = 16.4473(13) Å, and β = 99.398(6)° for complex I and a = 15.7117(12) Å, b = 15.2785(15) Å, c = 16.5247(15) Å, and β = 99.398(7)° for complex II. These complexes belong to the ionic type. The dioxonium cation [H₅O₂]⁺ in the form of the two-unit cluster [H₃O · H₂O]⁺ is stabilized by the strong hydrogen bond OH?O [O?O, 2.353(4) Å] and encapsulated by the crown ether. Each oxygen atom of the dioxonium cation also forms two oxygen bonds O?O(crown). The crown ether adopts an unusual two-level (pocket-like) conformation, which provides a complete encapsulation of the oxonium associate. The interaction of the cationic complex with the anion in the crystal occurs through contacts of the C-H?F type.     

Characteristic of spontaneous polarization in Li<Subscript>2</Subscript>Ge<Subscript>7</Subscript>O<Subscript>15</Subscript> crystals

The temperature dependence of spontaneous polarization in Li₂Ge₇O₁₅, a ferroelectric with one polarization axis, is studied in the temperature range from 4.2 K to T_C. An unusual character of spontaneous polarization associated with the change of the crystal behavior from the Ising to multipole type is revealed in the vicinity of T_C. The low value of spontaneous polarization is explained not by the relation between certain physical quantities, but rather by the interaction of the components of higher order (n > 2) electric moments which, by definition, have rather low values. The Li₂Ge₇O₁₅ structure is built by macrofragments consisting of two types of mesotetrahedra whose distortion results in the appearance of pseudopolarization of the nonvector type.     

Study of the structure and electrical conductivity of lithium-conducting polymer electrolytes based on PEG-1500—LiX (X = SCN,N(CF3SO2)2)

Russian Chemical Bulletin - A comprehensive study of lithium-conducting polymer electrolytes based on polyethylene glycol 1500 and lithium salts (LiSCN and LiN(CF3SO2)2) was carried out using...     

Specific features of the growth of A II B VI films on (0001)Al2O3 substrates

The structure and orientation of CdTe and ZnO films on sapphire have been investigated for different techniques of pregrowth substrate treatment. Polycrystalline CdTe films are found to grow of substrates unannealed or annealed in vacuum at a residual pressure P < 0.13 Pa. Epitaxial CdTe films with the sphalerite cubic structure, oriented parallel to the substrate by the (111) plane, grow on substrates annealed in air at a temperature of 1000°C or more and having a system of smooth terraces and steps on the surface. For ZnO films with a wurtzite hexagonal structure obtained by magnetron sputtering, a similar correlation between the structural quality and the regime of treatment of sapphire substrates is observed. It is shown that thermal annealing of (0001) sapphire plates in air is the optimal way of substrate preparation for growing epitaxial ZnO films with the base orientation. The obtained epitaxial CdTe films contain a certain amount of structural defects (mosaicity and twins), while the epitaixal ZnO films treated in the same way are close to perfect.