DIFFUSE-SCATTERING FROM YBA2CU3O7-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 YBa2Cu3O7- produces a Magneli series, YBa2Cu3O7(n/(2n+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, (1/2,0,0), 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. © 1990 The American Physical Society.