Textured and single-crystalline filaments of YBa2YCu3O7-δ containing dispersions of ∼1 μm BaY2CuO5 particles were fabricated by the laser-heated floating zone technique. The volume fraction of the superconducting phase decreased linearly with increasing growth rate over the entire range investigated, from 1.1 to 8.33 μm/s. The effects on the critical current density (Jc) of grwoth rate (R), filament orientation with respect to applied magnetic field, and temperature were investigated by magnetization measurements. The samples were solidified with planar front, at velocities below 3.1 μm/s. Jc increased with growth rate in these samples, despite the observed decrease in the volume fraction of Ba2YCu3O7-δ. The samples solidified with cellular or dendritic fronts at growth rates above about 3.1 μm/s. The critical current density of these samples decreased with increasing growth rate, as expected. Magnetization measurements performed in a field of 0.05 T applied perpendicular to the sample axis and transport measurements in self-field resulted in Jc values larger than 105 A/cm2 at 77.3 K. A weak field dependence of Jc was observed in a single-crystalline filament at and below 50 K. For the same sample, magnetization Jc values close to 106 A/cm2 at 30 K and in excess of 3×106 A/cm2 at 4.2 K were measured with the applied field perpendicular to the sample axis. The magnetization of a single-crystalline sample measured in a perpendicular fild at different angles of rotation (θ) of the sample about its axis followed a dependence of the type ΔM = A + B |cosθ|.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering