Oxygen-vacancy ordering in the ${\mathrm{Ba}}_2\mathrm{Y}{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}$ ($0\le x\le 1$) superconducting system

Diffuse scattering streaks or bands have been observed in electron diffraction photographs for samples belonging to the superconducting system ${\mathrm{Ba}}_2\mathrm{Y}{\mathrm{Cu}}_3{\mathrm{O}}_{7-x}$ ($0\le x\le 1$). In situ experiments show that this diffuse scattering can be associated with short-range ordering of oxygen vacancies. The same vacancy ordering occurs in previously reduced samples. Three types of diffuse scattering are observed, each corresponding to a short-range-order scheme.