Magnetic Properties of YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ Melt Textured Samples Prepared by Powder Melting Process and Quench and Melt Growth Techniques

The microstructure and magnetic properties of the melt textured YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ samples prepared by the powder melting process, in which Y$\text{}_{2}$Cu$\text{}_{2}$O$\text{}_{5}$ and BaCuO$\text{}_{2}$ were used as precursors, and those prepared by the quench and melt growth method are described and compared. The lattice parameters and T$\text{}_{c}$ values for the samples prepared by the both techniques were similar. The penetration and the spatial distribution of the magnetic flux in the superconducting samples was imaged by means of a field-mapping device using a Hall probe. In the range of low magnetic fields up to 820Am$\text{}^{-1}$ no significant differences in penetration of magnetic flux between the samples prepared by the powder melting process and the quench and melt growth were observed. The mapping could not resolve any grain boundaries, single grains and structural defects. By the ac and virgin volume magnetisation characteristics, which were measured in the zero-field cooled condition by a 2nd order SQUID gradiometer, no weak links were identified. Better magnetic properties of the quench and melt growth samples in high magnetic fields can be explained by the differences in microstructure and/or by the risen content of the finely dispersed 211 and Pt containing phases. The increase factor in magnetisation is about 2.5. Some aspects of the Bean model for textured YBa$\text{}_{2}$Cu$\text{}_{3}$O$\text{}_{7-δ}$ samples are discussed.