Diffuse scattering from ${\mathrm{YBa}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ oxide caused by Magneli-type plane defects

It is shown that if a periodical faulting of the double-period orthorhombic (1/200) phase in ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ produces a Magneli series, ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7(\mathrm{n}/(2\mathrm{}\mathrm{n}+1)}$, with a regular superlattice spots at [1/2+1/2(2n+1),0,0], the random faulting results in either broadening the (1/200) diffraction maximum or its splitting into two maxima, (1/2±ε,0,0), depending on the stoichiometry. The observation of these effects is a strong argument in favor of an assumption that this compound is inherently inhomogeneous due to the accommodation of nonstoichiometry by means of the formation of interstitial plane defects.