We report the epitaxial growth and superconducting properties of Y2O3-added YBa2Cu3Ox (YBCO) films grown on SrTiO3-buffered MgO substrates by pulsed-laser deposition using surface-modified YBCO targets. Areas of Y2O3 sectors on the YBCO target were increased to 5.44% and 9.22% of the total YBCO pellet in order to find a correlation between the Y2O3 content, morphology, and the pinning properties of YBCO+Y2O3 mixed films. The maximum global pinning forces, FP, at 77 K were 14.3 GN m−3 and 1.15 GN m−3 for the Y2O3 5.44A% and 9.22A%, respectively. The 5.44A% Y2O3-added sample presents a very high value of pinning force at 77 K, approaching the value obtained in YBCO films with added BaZrO3 nanorods, but with less depression in the superconducting critical temperature, Tc. In accordance with scanning transmission electron microscopy (STEM) observations, both films present nanoparticulate Y2O3 dispersed in a YBCO matrix where Y2Ba4Cu8O16 (Y248) intergrowths were also observed. Consistent with the strong pinning theory, the size and distribution of randomly dispersed Y2O3 particles are optimal for the flux pinning of a 5.44A% Y2O3-YBCO film, while in the case of a 9.22A% film, the YBCO matrix is degraded by jampacked Y248 intergrowth, which leads to a comparatively poor pinning performance. We further used the single-vortex dynamics model to account for vortex pinning in the samples. The 5.44A% Y2O3-YBCO film result shows good agreement with the model fit up to 4 T of the applied magnetic field.

With respect to the potential application as cryo-permanent magnets, melt-textured YBaCuO bulk parts were used to investigate various pulsed magnetization processes employing pulsed copper coils. Results for different multi-pulse processes including different peak fields, pulse durations, temperatures and geometries are compared. The strong current-carrying capabilities of HTS material, even for currents above the critical current J c , result in strong shielding effects, in particular for short pulse durations. It turns out that the inhomogeneities present in all real materials play an important role for the initial magnetic flux penetration. To fully magnetize the bulk samples, the non-stationary conditions and geometrical effects require peak fields, which substantially exceed twice the saturation magnetization measured at the sample surface. Transient magnetizations as well as shapes and absolute values of trapped flux profiles are reported.

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An independently oxidized AgMn alloy is used to gauge the overall tensile strength of technical Ag/Bi2223 composite flat wire through the contributions of individual constituent strengthenings. Theoretical analysis based on the rule of mixtures shows similarity between measured and calculated curves of the composite at room temperature (RT) and 77 K. The elastic modulus of the composite wire, deduced from initial and loading/unloading curves, is found to be around 95-98 GPa, while for Bi2223 filaments, the modulus of elasticity was estimated to be 129 GPa. The effect of thermal cycling between RT and 77 K on the electromechanical properties of the wire is also examined. The critical current is significantly reduced by tensile strain above 0.4% but not affected by the short thermocycle when measured across different specimens. Finally, the relation between the fracture strain and the strain span of the Bi2223 filaments is found to accommodate an intrinsic filament fracture strain of about 0.04-0.11% in the wire.

High-temperature superconductor bulk parts are batch processed using a semi-automated processing technique based on the melt-texturation process. Levitation properties under static and dynamic load levels were analysed using a test bench with a three-dimensional force sensor unit. Measurements of levitation force give no detailed suggestions on texture, secondary domains or cracks. Therefore other measurements to control homogeneity of the bulk were performed. Texture on full-size pellets (FWHM ) was verified by elastic neutron scattering. To study the influence of local texture on properties a pellet was divided into nine segments. Preliminary results indicate that a correlation between neutron data and levitation force needs further investigations. Flux maps of samples magnetized by permanent magnets or by a pulsed magnetization unit were used to verify the homogeneity and domain structure of the material and to evaluate macroscopic critical currents.