Domainlike defects observed in the high-temperature superconductor Y-Ba-Cu-O

Transmission-electron microscopy of the high-superconductivity-transition-temperature oxide ${\mathrm{Y}}_1{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_x$ reveals the presence of planar defects along [110] direction more-or-less uniformly spaced (spacing ∼300 Å) and dispersed throughout the specimens. These defects persisted on cooling down to the transition temperature (93 K), but disappeared on heating above 400°C in in situ experiments inside the electron microscope. The possible role of these "domains" or interfaces in superconductivity is discussed.