[en] This invention relates to granular metal and metal oxide superconducting films formed by ion beam sputter deposition. Illustratively, the films comprise irregularly shaped, randomly oriented, small lead grains interspersed in an insulating lead oxide matrix. The films are hillock-resistant when subjected to thermal cycling and exhibit unusual josephson-type switching characteristics. Depending on the oxygen content, a film may behave in a manner similar to that of a plurality of series connected josephson junctions, or the film may have a voltage difference in a direction parallel to a major surface of the film that is capable of being switched from zero voltage difference to a finite voltage difference in response to a current larger than the critical current

[en] Cluster formation in metallic crystal lattices is important for most high-temperature superconductors

[en] The superconducting properties of thin granular lead films provide evidence for the existence of clusters which mitigate electrostatic charging effects and allow Josephson coupling to remain favorable in samples with normal-state sheet resistance near the maximum metallic resistivity of 30 000 Ω/sq. The disappearance of zero-resistance transitions together with the precipitous onset of temperature broadening in this range is therefore most likely associated with the localization of electronic states

No abstract available

[en] High-resolution x-ray diffraction (HRXRD) measurements of strained-layer superlattices (SLS's) have been carried out using a four-crystal monochromator. A wide asymmetric range of sharp higher-order x-ray satellite peaks is observed indicating well-defined periodic structures. Using a kinematical diffraction step model very good agreement between measured and simulated x-ray satellite patterns could be achieved. These results show that this x- ray method is a powerful tool to evaluate the crystal quality of SLS's

[en] Superconducting transition temperatures of some binary transition-metal borides and a new series of ternary transition-metal borides are reported. The variation of T/sub c/ vs electron/atom ratio and the crystal chemical behavior of the borides in relation to their superconducting behavior are discussed. (auth)

No abstract available

[en] The stabilization of A15 Nb₃Ge in its high T/sub c/ form is of fundamental interest and also technologically important. One factor, the influence of gaseous impurities, has been discussed for some time by various authors. A second, epitaxial growth, was studied on Nb₃Ir and an improvement of T/sub c/ and phase purification of the Nb₃Ge was observed, although T/sub c/ did not exceed that of single sputtered films prepared by others. Gavaler et al. have reported that impurities near the substrate-film interface expand the A15 cell and suggest that subsequent deposition results in a homoepitaxial growth with cell size decreasing with increasing thickness. This is consistent with the observed increse in T/sub c/ with increasing film thickness. The results of similar experiments using the getter sputtering method of film preparation are reported. Of particular interest was examination of (1) the structural and phase relationships of Nb₃Ge films prepared with and without an A15 underlayer; (2) how variation of film thickness and deposition temperature affected these properties of T/sub c/; and (3) the potential application and usefulness of multilayered films for the stabilization of A15 Nb₃Si

[en] The interfacial structure of a lattice-matched InGaAs/InP/(100)InP superlattice with a long period of ∼630 Angstrom has been studied by fully dynamical simulations of high-resolution x-ray diffraction curves. This structure exhibits a very symmetrical x-ray pattern enveloping a large number of closely spaced satellite intensities with pronounced maxima and minima. It appears in the dynamical analysis that the position and shape of these maxima and minima is extremely sensitive to the number N of molecular layers and atomic spacing d of the InGaAs and InP layer and in particular the presence of strained interfacial layers. The structural model of strained interfaces was also applied to an epitaxial lattice-matched 700 Angstrom InP/400 Angstrom InGaAsP/(100)InP beterostructure. 9 refs., 3 figs

[en] Sc-Cr alloys stabilized by adding small amounts of B were found to exhibit superconductivity, the optimum composition being Sc₀.₇₅Cr₀.₁₈₇₅B₀.₀₆₂₉ x-ray diffraction patterns showed that the sample contained 15-20 percent of a new metastable superconducting phase, whose composition was estimated to be Sc₂.₁₅Cr₀.₈₅B/sub x/ (x < 0.01). 6 refs