Large-area quantification of BaCeO_3 formation during processing of metalorganic-deposition-derived YBCO films

A method is described for the quantification of BaCeO_3 formation during the growth of YBa_2Cu_3O_7– x (YBCO) films on CeO_2 buffer layers. The method is based on the selective etching of BaCeO_3 followed by inductively coupled plasma (ICP) excitation spectroscopy. A 10% HNO_3 solution, at room temperature, dissolved BaCeO_3 and YBCO in minutes but did not significantly etch CeO_2 films. ICP excitation spectroscopy was used to quantify the extent of the reaction over macroscopic areas of film (∼1 cm^2). BaCeO_3 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 BaCeO_3 formation through a metalorganic deposition (MOD)-derived CeO_2 layer follows the parabolic growth law. Almost the entire ceria cap layer was consumed by the growth of BaCeO_3 after 2 h at 760 °C in the MOD process examined. BaCeO_3 growth was substantially slower at 725 °C; only 25 ± 3% of the ceria layer reacted.