Raman investigation of the metastable barium cuprate BaCu3O4 in thin films

Metastable BaCu3O4 has been synthesised by MOCVD on perovskite substrates. Strain effects lead to an epitaxial island-growth of micrometer-sized cryst allites with two orientations relative to the substrate surface. They were used for a polarized single crystal analysis by micro-Raman spectrometry. T he results can be used to detect BaCu3O4 as an impurity phase in RBa2Cu3O7 thin films with a mole fraction level of less than 1%, a sensitivity which exceeds that of XRD by at least one order of magnitude. (C) 1999 Elsevier S cience B.V. All rights reserved.