Publications

The structure of vacuum annealed amorphous sputtered Cr and CrNi (55:45) thin films has been studied by transmission electron microscopy (TEM) and electron diffraction (TED). The thin films with thicknesses ranging from 150 to 600 angstrom were annealed while still on their alkali halide substrates under high vacuum at temperatures ranging from 200 to 370-degrees-C. The TEM and TED data permitted to establish the annealing conditions (temperature, duration), which lead to the nucleation and growth of nanosized crystals in the Cr and CrNi icosahedral glasses.

A magnetron with 75 cm2 effective area for reactive sputtering in pure oxygen was realised by modifying AV 500 standard equipment. Dielectric Al2O3 and Ta2O5 thin films of 30 cm2 area and thickness between 0.1-1-mu-m were obtained. Their amorphous structure and excellent visible transmission recommend them for electroluminescent devices production.1-3

Amorphous ribbons of (Fe1-xYx)84B16 with 0 < x < 0.21 were studied using Mossbauer and magnetic measurements. The results proved a short-range order interaction in the prepared samples and nonhomogeneous regions induced by yttrium presence.

The crystalline phases in the superconducting ceramic Bi:Sr:Ca:Cu2:O(x) exhibiting either low superconducting transition (almost-equal-to 80 K) or both, low and high superconducting transitions (almost-equal-to 110 K) are identified by X-ray and electron diffraction. Two types of modulated structures are observed and their relation to T(c) is discussed within the frame of the oxygen-displacive mode theory.

We consider homogeneous states of quantum multicomponent plasmas described by a spin-independent Hamiltonian. Using generalized-moment inequalities we show that the relation between the response and the correlation functions of the spin magnetic moments approaches the classical one in the infinite-wavelength limit (k-->0). For small k, the first correction is of order k2 and is bounded by the semiclassical correction.

The temperature dependence of the critical current density at high temperatures and in weak applied magnetic field for YBa2Cu3O7-y ceramic samples with a pronounced granular character is analyzed. The experimental results can be explained in terms of thermally activated motion of the intergrain Josephson vortices at grain boundaries, which may be an indication that the actual limiting factor for the critical current density in ceramic samples results from a weak pinning force density for the intergrain vortices rather than from the weak-link quenching.