Large-area quantification of BaCeO₃ formation during processing of metalorganic-deposition-derived YBCO films

A method is described for the quantification of BaCeO₃ formation during the growth of YBa₂Cu₃O_7–x (YBCO) films on CeO₂ buffer layers. The method is based on the selective etching of BaCeO₃ followed by inductively coupled plasma (ICP) excitation spectroscopy. A 10% HNO₃ solution, at room temperature, dissolved BaCeO₃ and YBCO in minutes but did not significantly etch CeO₂ films. ICP excitation spectroscopy was used to quantify the extent of the reaction over macroscopic areas of film (∼1 cm²). BaCeO₃ peak areas were measured by x-ray diffraction (XRD) and calibrated to the ICP excitation spectroscopy results. XRD and ICP excitation spectroscopy results indicated that BaCeO₃ formation through a metalorganic deposition (MOD)-derived CeO₂ layer follows the parabolic growth law. Almost the entire ceria cap layer was consumed by the growth of BaCeO₃ after 2 h at 760 °C in the MOD process examined. BaCeO₃ growth was substantially slower at 725 °C; only 25 ± 3% of the ceria layer reacted.