Electron microscope studies of sodium and lithium intercalation in TiS2

Lithium and sodium intercalation in TiS₂ have been studied by transmission electron microscopy using lattice imaging and diffraction contrast techniques. Na_xTiS₂ samples (0 ≤ x ≤ 0.6) from $\text{Na}\text{NaI}$ in propylene carbonate/TiS₂ batteries were found to contain a complex variety of phases inhomogeneous on a fine scale. Observations showed variable staging and a 2H phase not previously reported for this system at ambient temperatures. Observations on both Na_xTiS₂ and chemically prepared Li_xTiS₂ showed highly dislocated structures. A model is proposed whereby dislocations are introduced to accommodate misfit strains caused by nonuniform intercalation and, in the case of Na_xTiS₂, to initiate phase transformations, leading to potentially irreversible structural changes in cycled material.     

Étude de l'adsorption électrochimique de l'oxygène sur des lames minces d'or par la mesure de leur résistance électrique

The electrical resistance changes of thin gold film electrodes of preferential orientation [111] with film thickness and potential have been studied. The applicability of the Fuchs-Sondheimer (FS) relation to the decrease of resistance observed at the first negative polarization and the first few potential sweeps for different thicknesses have shown that this phenomenon is due to a surface process, interpreted as a cleaning of the electrodes. The resistance changes observed during the electrochemical adsorption and desorption of oxygen also obey the FS relation. The analysis of the resistance variation with the charge exchanged during these reactions has allowed us to show that the electrochemical adsorption of oxygen, on these gold films occurs by a two-dimensional island mechanism with formation of different structures of the surface layer. The values of the resistivity change caused by the adsorption of 1% oxygen atoms (with respect to the total number of metal atoms in the films) at low coverage have been compared with those observed in other systems (metal-gas, metal-metal).     

Influence of extrasphere cations on the thermal stability of hydrates of iron (III) ethylenediaminetetraacetates

Russian Chemical Bulletin -     

Inflationary scenario in the supersymmetric economical 3-3-1 model

We construct the supersymmetric economical 3-3-1 model which contains inflationary scenario and avoids the monopole puzzle. Based on the spontaneous symmetry breaking pattern (with three steps), the F-term inflation is derived. The slow-roll parameters ∈ and η are calculated. By imposing as experimental five-year WMAP data on the spectral index n, we have derived a constraint on the number of e-folding N _Q to be in the range from 25 to 50. The scenario for large-scale structure formation implied by the model is a mixed scenario for inflation and cosmic string, and the contribution to the CMBR temperature anisotropy depends on the ratio M _X /M _Pl. From the COBE data, we have obtained the constraint on the M _X to be M _X ∈ [1.22 × 10¹⁶, 0.98 × 10¹⁷] GeV. The upper value M _X ≃ 10¹⁷ GeV is a result of the analysis in which the inflationary contribution to the temperature fluctuations measured by the COBE is 90%. The coupling α varies in the range: 10⁻⁷−10⁻¹. This value is not so small, and it is a common characteristics of the supersymmetric unified models with the inflationary scenario. The spectral index n is a little bit smaller than 0.98. The SUGRA corrections are slightly different from the previous consideration. When ξ ≪ 1 and α lies in the above range, the spectral index gets the value consistent with the experimental five-year WMAP data. Comparing with string theory, one gets ξ < 10⁻⁸. Numerical analysis shows that α ≈ 10⁻⁶. To get inflation contribution to the CMBR temperature anisotropy ≈90%, the mass scale M _X < 3.5 × 10¹⁴ GeV.     

Synthesis, crystal structure and reactivity of uranium(IV) complexes with p-tert-butylcalix[4]arene ligands

Reactions of UCl4 with 25,27-dimethoxy-5,11,17,23-tetra-tert-butylcalix[4]arene (H2Me2calix) in THF or pyridine at 80 degrees C gave [UCl2(Me2calix)L2] [L = THF (1) or pyridine (2)]. Similar treatment of U(acac)(4) (acac = MeCOCHCOMe) with H2Me2calix in THF or pyridine afforded [U(acac)2(Me2calix)] (3). The bis-calixarene compound [U(Me2calix)(H2calix)] (4) was obtained by reaction of U(OTf)4 or U(OTf)3 with H2Me2calix in pyridine at 110 degrees C. Treatment of UCl4 with H2Me2calix in pyridine at 110 degrees C gave [Mepy][UCl2(Hcalix)(py)2] (5) resulting from demethylation and acid cleavage of the methoxy groups of the calixarene ligand of 2. Adventitious traces of air were responsible for the formation of [Hpy][Mepy]4[{UCl(calix)}3(mu3-O)][UCl6] (6) during the reaction of UCl4 and H2Me2calix, and of [{U(Me2calix)(mu3-O)LiCl(THF)}2] (7) during the reaction of 2 with tBuLi. The X-ray crystal structures of 1.2THF, 2.2py, 3.0.25L (L = THF and py), 4.2py, 5, 6.3py and 7.THF have been determined.