Characterization of co-evaporated SmBa₂Cu₃O ₇ coated conductors by polarized-raman scattering spectroscopy

SmBa₂Cu₃O₇(SmBCO)-coated conductors were grown on IBAD-MgO templates by in-situ co-evaporation using a drum-in-dual-chambers system. The conductors, which had a coating thickness of up to 3 μ, showed a critical temperature of 92 ̃ 94 K and a critical current of 150 ̃ 625 A/cm-w at 77 K in a self-field. The phonon modes and cation disorder of the SmBCO-coated conductors were examined by polarized Raman scattering spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy. XRD showed (00l) peaks for the SmBCO phase. The Raman spectra revealed common vibration modes, including Ba-Ba stretching, Cu2-Cu2 stretching, O(2)+/O(3)-, and apical O(4) modes. In addition, polarized-Raman spectra were obtained to examine the crystal orientation and grain growth behavior. Structural information from the Raman spectra turned out to be useful to determine the optimal thickness of SmBCO-coated conductors with high critical currents.