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Studies the strain tolerance of doctor blade tapes of a high-temperature superconductor to determine the suitability of these materials for magnet conductors. Method of the study; Results and discussion; Conclusion.

Presents a study that utilized transport currents in a cross strip superconducting-normal metal-superconducting (SNS) Josephson junction to bias the current-voltage characteristics of the junction. Features of SNS junctions; Approximation of the current-voltage characteristics of SNS junctions.

Thermodynamic critical fields, H[sub c], have been measured for the La[sub 2-x]Sr[sub x]CuO[sub 4] family of superconductors in order to determine the changes in free energy of the system as the number of carriers is reduced. Magnetization vs. magnetic field curves are thermodynamically reversible over large portions of the H-T plane, so the free energy is well defined in these regions. Magnetization vs. field data are then fit to theoretical models to determine the thermodynamic critical fields. As the Sr concentration is changed from x = 0.10 to 0.23, the values of H[sub c](T = 0) goes through a maximum at optimum doping in a manner similar to the T[sub c] vs x curve. The ratio of H[sub c](T = O)/T[sub c] also peaks in the region of x somewhat larger than optimum doping. As the value of x increases from underdoped to optimum doping, the cross-over temperature in the M[sub sc] vs. T curve, T[sup *], approaches the transition temperature. In the overdoped regime there is no crossing in these M[sub sc] vs. T curves. [ABSTRACT FROM AUTHOR]

Measurements of 10 GHz microwave surface resistance, R[sub s], of dense MgB[sub 2] wire and pellet are reported. Significant improvements are observed in the wire with reduction of porosity. The data lie substantially above the theoretical estimates for a pure Bardeen-Cooper-Schrieffer s-wave superconductor. However, the R[sub s] (20 K) of the wire is an order of magnitude lower than that of polycrystal YBa[sub 2]Cu[sub 3]O[sub 6.95] and matches with single-crystal YBa[sub 2]Cu[sub 3]O[sub 6.95]. The results show promise for the use of MgB[sub 2] in microwave applications. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Procedures have been developed for the preparation of long slender fibers of Bi-Sr-Ca-Cu-O using a gas jet to shape and freeze the material. The fibers emerge in amorphous form and are converted to the Bi[sub 2]Sr[sub 2]Ca[sub 1]Ca[sub 2]O[sub x] phase by subsequent heat treatment. Magnetization and scanning electron microscopy studies show the material to be a very fine grained bulk superconductor with intragranular critical currents of 7 × l0[sup 6] A/cm² at 5 K and 1.8 T. [ABSTRACT FROM AUTHOR]