MAGNETIC-FIELD DISTRIBUTION ABOVE A SUPERCONDUCTING Y-BA-CU-O SAMPLE AS AN INDICATION OF SAMPLE INHOMOGENEITIES

A method based on the measurement of the distribution of the magnetic field B(sz) produced by shielding currents in a superconducting Y-Ba-C u-O disc has been used to detect macroscopic inhomogeneities of the sa mple. A small-active-area Hall probe was used for magnetic field measu rement. The phase composition and microstructure of the sample were de termined by the XRD method and SEM respectively. Regions with irregula r distribution of B(sz), corresponding to degraded current-carrying pr operties, were found in the investigated sample. An attempt to correla te observed irregularities with some features of the phase composition and microstructure has been made.