The anisotropic thermal diffusivity α of the highly c-axis-oriented Y–Ba–Cu–O bulk superconducting crystals has been measured quasi-simultaneously with the thermal conductivity κ. The estimated values of the specific heat C by use of α and κ values parallel and perpendicular to the c-direction agreed with each other. In these crystals prepared by the modified melt texture growth (MMTG) method, fine Y2BaCuO5 particles are dispersed in the YBa2Cu3O7- x superconducting matrix phase. Based on a simple model, the thermal diffusivity and the specific heat of the YBa2Cu3O7- x matrix phase are separated using independently measured data of a Y2BaCuO5 polycrystal. The influence of Y2BaCuO5 particles on the thermal properties of the mixed crystals is discussed.

The -plane thermal conductivity ( ), thermal diffusivity ( ) and thermoelectric power ( ) were measured for the highly-oriented Ag-doped superconducting materials Sm 1+2 Ba 2+ Cu 3+ O 7+5 ( = 0 1 0 4) prepared by a melt process. The absolute value of and its characteristic enhancement below were suppressed with increasing content of the Sm 2 BaCuO 5 (Sm211) secondary phase, while they were enhanced with increasing content of doped-Ag. The application of the magnetic field up to 10 T clarified that the phonon scattering by vortex was most enhanced with the applied field perpendicular to the -plane. The trapped magnetic also seriously suppressed the ( ) enhancement.

Abstmct-One of the advantages of magnetic levitation using high-temperature superconducting (HTS) bulk i s that stable levitation can be achieved without any control systems. We have been investigating the electromagnetic behaviors of HTS bulk to realize a two-dimensional magnetic levitating transporter without any fixed guides. The characteristics of lift and stability are key parameters to design and optimize such a device. We measured the lift and the restoring force of a YBCO bulk, displaced by a distance in lateral direction, for various field-cooling conditions and permanent-magnet arrangements, Both lift and restoring force are closely related to the a i r gap in the field-cooling process, distance between the permanent magnets, number of permanent magnets, and permanent magnet arrangement, that is, external magnetic field distribution. The most suitable arrangement o f permanent magnets depends on the required levitation height and the weight of the levitating part. I t can be considered that the size of the levitating part and geometry are also very important to determine the optimal arrangement in the maglev device.

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We investigated the effect of Dy2BaCuO5 (Dy-211) addition to DyBa2Cu3Ox (Dy-123) bulk on superconducting properties. The composite was fabricated by a top seeding method in a temperature gradient in air. The single-domain Dy-123 pellets were about 18 mm in diameter and 5 mm in thickness. The maximum remnant Jc value and the maximum trapped field at 77.3 K were 30 kA cm−2 and 0.23 T, respectively, for the molar ratio Dy-123/Dy-211 of 1/0.3. In the samples with molar ratios 1/0.1, 1/0.2 and 1/0.3, the number of dispersed Dy-211 particles increased with increasing Dy-211 content. In the sample with the molar ratio 1/0.4, a coarsening of Dy-211 particles was observed.