Microstructure and magnetization of Y-Ba-Cu-O prepared by melt quenching, partial melting and doping

Y-Ba-Cu-O samples prepared by means of a variety of melt-based techniques exhibit high values for their magnetic properties compared with those of samples prepared by solid state sintering. These techniques include single-stage partial melting as well as melt quenching followed by a second heat treatment stage, and they have been applied to the stoichiometric 123 composition as well as to formulations containing excess yttrium or other dopants. The structure of these melt-based samples is highly aligned, and the magnetization readings exhibit large anisotropy. At 77 K and magnetic field intensities of about 2 kOe, diamagnetic susceptibilities as high as -14 x 10(exp -3) emu/g were obtained in the cases of melt-quenched samples and remanent magnetization values as high as 10 emu/g for samples prepared by partial melting

Melt-processed bulk superconductors: Fabrication and characterization for power and space applications

Melt-process bulk superconducting materials based on variations on the base YBa2Cu3O(x) were produced in a variety of shapes and forms. Very high values of both zero-field and high-field magnetization were observed. These are useful for levitation and power applications. Magnetic measurements show that the effects of field direction and intensity, temperature and time are consistent with an aligned grain structure with multiple pinning sites and with models of thermally activated flux motion