Publications

The gradual substitution of Cu by Ag in the Al62Cu25.5-xAgxFe12.5 icosahedral phase (x less than or equal to 10) is investigated by X-ray diffraction from the viewpoint of the induced structural changes. The phonon and random phason disorders, estimated from diffraction linewidths, increase with x, the latter showing, however, an induction range of Ag concentrations. EXAFS results at the CuK and FeK edges show. for low Ag contents, and enhanced disorder in the first coordination sphere, partly relaxed for higher x values. The 6D hypercubic lattice parameter is found to be independent of the Ag content, despite the large diameter of monovalent Ag. The latter facts suggest a d-sp hybridization of the Ag bonds to the surrounding Al, taking place above a certain x value.

SnO2 sensors were prepared by precipitating Sn(OH)(4) from an aqueous solution of SnCl4 or by evaporating SnO2 in the UHV. Subsequent X-ray and TEM measurements show grain sizes in the nanometer range after annealing at different temperatures or annealing times. The effect of Pt and Pd doping upon the response to CO is studied. Parameters, which we focused on, are sensor signal dependent on the operating temperature and dependent on the gas concentration. The results for ceramic sensors are compared with those for thin film sensors.

First searches for the coherent dissociation of relativistic oxygen nuclei into four alpha particles are reported. It is shown that reactions of this type are characterized by a significantly lower decay temperature than the conventional multifragmentation of residual projectile nuclei. The momentum spectra and correlations of alpha particles are not reproduced by the simple statistical model of direct fragmentation. The possibility that the oxygen nucleus undergoing fragmentation acquires a nonzero angular momentum in the collision process is discussed.

The results of the potentiostatic polarization studies taken on some Al-Mm-MT metallic glasses in reducing acid media are presented. The rest potentials development and the electrochemical parameters evaluated from the anodic and cathodic curves were correlated with the alloys composition, and related to those of the alloying components in crystalline state. Our results indicate that: alloying with rare earths does not affect interface processes; the transition metals interfere with the hydrogen reduction kinetics determining its acceleration by increasing Ni content in the alloy composition; substitution of Ni by Fe contributes to corrosion rate reduction, to passive state extension and stabilization, so that Al-Mm-Fe alloy behaves better than Al-Mm-(Fe, Ni) and Al-Mm-Ni alloys.

Using a high electric field method, the anchoring energy was measured for tilted homogeneous cells filled with nematic liquid crystals (5CB, ZLI 1132). These cells contain aligment layers of five different types obtained either by SiO depositions at various incidence angles or by special polyvinylic alcohol (PVA) coatings. The observed differences in the anchoring energy values are due to the differences in the layer topography.

LiNbO3 crystals with three different stoicliiometries(0,88; 0,945 and 1) in the melt were grown and dcped with the same concentration of Nd3+ (0.33%). The Nd3+ centres were systematically investigated by laser spectroscopy for these three crystals. The same Nd3+ centres were obtained for all stoichiometries but its relative distribution depends on the [Li]/[Nb] ratio.

Three alternative routes of the oxalate method for synthesis of the high-T-c superconducting oxide Bi1.7Pb0.3Sr2Ca2Cu3O10+x have been studied. The best results were obtained using the compound III as precursor.

New experimental results related to the harmonic dependence of the characteristics of SC-cut quartz resonators on various material and electrode parameters are presented. On the basis of the analysis of SC-cut trapped-energy resonators vibrating in the coupled thickness-shear and thickness-twist in the vicinity of the fundamental and odd overtone thickness-shear frequency dependencies were established of effective mass-loading, effective coupling coefficient, motional capacitance and static capacitance on electrode material and dimensions. The results put into evidence the influence of the non-uniform distribution of motion on behaviour of the SC-cut resonators. The plane-parallel polished SC-cut quartz plate of 14mm diameter with different thickness Ag and CrAu electrodes and two values of electrode diameter were used for the experimental investigations.