Determination of the composition of an oxidized Tb_0.32Dy_0.67Fe_1.92 thin film by anomalous x-ray scattering

In this work, Tb_0.32Dy_0.67Fe_1.92 thin films were prepared by DC magnetron sputtering and then annealed at 550 °C in vacuum. The structure of sputtering Tb_0.32Dy_0.67Fe_1.92 thin films and their surface oxidation layers were characterized by anormalous X-ray diffraction. Diffraction peaks of rare-earth oxides, Tb₂O₃, Dy₂O₃ and other non-stoichiometric peaks were found. Since the structure of Tb₂O₃ is the same as Dy₂O₃, also the lattice constant is almost similar, the composition of Tb₂O₃ and Dy₂O₃ cannot be determined by standard XRD separately. By using synchrotron radiation anomalous X-ray scattering, the amount of Tb and/or Dy oxidized at different annealing conditions were determined. In addition, using the anomalous X-ray diffraction and electron probe micro-analyzer, the Fe clusters phase segregated from the bulk matrix without oxidation was also identified. These pure Fe cluster without oxidation might be due to the presentation of Dy and Tb matrix which protect Fe from oxidation.