Magnetic susceptibility of sintered and powdered Y-Ba-Cu-O

Abstract
The real and imaginary parts of ac susceptibility of a sintered Y1Ba2Cu3O7−δ superconductor were measured before and after powdering. The temperature-dependent susceptibility may be separated into two contributions, one sensitive and the other relatively insensitive to the magnitude of the measuring field. The former is partially suppressed by coarsely crushing the sample. It is completely suppressed after finely powdering, whereupon the susceptibility curves become insensitive to the magnitude of the measuring field. Several models apparently consistent with the results are discussed.