Effect of heavy atom disorder on the intensities of powder XRD lines of YBa₂Cu₃O_7-y

Abstract

It is shown that heavy atom disorder resulting from Y ↔ Ba, Ba ↔ Cu and Y ↔ Cu interchanges due to local stoichiometric constraints can cause significant changes in the intensities of X-ray powder diffraction lines of YBa₂Cu₃O_7-y . A comparison of the theoretically predicted intensities with published patterns for specimens prepared by the conventional dry route reveals that Ba ↔ Cu interchanges involving copper atoms in the CuO₂ planes can occur quite frequently and may be mistaken for (00l) texture.

Key Words:

• Heavy atom disorder
• high T _c superconductor
• YBa₂Cu₃O₇-y