Structural inhomogeneities in crystals of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}}

Structural inhomogeneities in crystals of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} are characterized using high resolution x-ray diffraction. Rocking curves and a high resolution specular radial scan show features indicating that the crystals are not truly single. The high resolution radial scan of a crystal that had a superconducting transition width of only one-half Kelvin, as determined by ac susceptibility, and appeared to be free of gross defects, when examined with conventional x-ray diffraction techniques, shows a distribution in the c-axis lattice parameter. These results suggest that crystals with sharp transitions should be carefully examined for the presence of structural anomalies which might influence the superconductive properties.