Detection by XRD of hidden defects in epitaxial Bi2 Sr2 CaCU2 O8 thin films grown by PLD

X-ray Diffraction (XRD) analysis of epitaxial Bi2 Sr2 CaCU2 O8 (Bi-2212) thin films grown by Pulsed Laser Deposition (PLD) reveals the presence of the two parent compounds Bi-2201 (calcium free) and Bi-2223 (calcium excess) within the main Bi-2212 phase. These stoichiometric defects are, in many cases, hidden by their dilution as random intercalates within the main matrix. A careful analysis involving subtle Bragg peak deviations with respect to their expected positions in the pure phase and, in some cases, a peculiar signature in the shape of the rocking curves allow us to detect and identify this kind of hidden defects.