Distribution of Magnetic Flux in Powder-Melting-Processed YBCO Superconductors

Using magnetic decoration technique, the distribution of magnetic flux in power-melting-processed Y-Ba-Cu-O superconductor has been studied in an applied field of 200 G at 64 K. The decoration patterns indicate that twin boundaries act as strong flux pinning sites and the nonsuperconducting Y2BaCuO5 (211) inclusions provide pinning sites in their vicinity by inducing lattice distortion. Chain-like vortex distribution, distorted hexagonal flux line lattice and anisotropic vortices have been observed.