Microstructure of melt-textured YBa2Cu3O7-δ

Abstract The microstructure of stoichiometric Bridgman melt-textured YBa 2 Cu 3 O 7-δ was investigated by transmission electron microscopy and electron diffraction. Crystal defects like twins, dislocations, small second-phase inclusions and lattice distortions are observed. The density of the dislocations is extremely high (1.7 × 10 10 / cm 2 ) and the average diameter of the second-phase inclusions (BaCuO 2 ) of 35 nm is rather small. The density of the inclusions amounts to 6 × 10 19 / m 3 . The formation of the microstructural defects and their influence on flux pinning is discussed. It is supposed that the observed lattice distortions are possible defects which cause the fish-tail effect.