Characterization of MBa₂Cu₃O_7-x Thin Films by Raman Microspectroscopy

Abstract

Thin film embodiments of MBa2Cu3O7-x (MBCO, M = yttrium or a rare-earth metal) prepared by several different deposition methods on a variety of substrates were investigated by Raman microspectroscopy. Several of the unique characterization capabilities of Raman spectroscopy in the analysis of MBCO thin films are highlighted by the results of these investigations. The Raman active phonons of the orthorhombic and tetragonal forms of MBCO that are most useful for characterization of textured MBCO films are diagrammed and discussed. A rapid procedure for qualitative texture mapping of MBCO thin films using Raman microscopy techniques is presented, and a new approach for investigating phase separation at the sub-micrometer level in MBCO thin films based on curve resolution of the MBCO Cu2 phonon is described. The assignment of a particular feature often observed in Raman spectra of MBCO films to cation disorder is reinforced by results of a cation substitution study. The depth of penetration of the laser into MBCO films and the type of information that can be obtained by varying the extent of defocusing of the laser are also discussed.

Progress in Nanoengineered Microstructures for Tunable High‐Current, High‐Temperature Superconducting Wires

“…The two spectra for each specimen are normalized to the YBCO O2+/O3-phonon. [91] We consistently find (with relatively few exceptions) that the spectral features attributable to YBCO in single spot static measurements show an excellent match to the moving scan averaged spectra. [92] Finally, low-magnification SEM imaging of single-layer MOD YBCO films typically shows a uniform surface morphology with few surface imperfections.…”

Local transport properties of coated conductors by laser-scan imaging methods

“…The black spectrum is similar to a previous report of polarized Raman scattering spectroscopy of SmBCO coated conductors [13]. This indicates that the normal surface of GdBCO has well-aligned orthorhombic compounds [15]. The changes between the two spectra are the intensities of an out-of-phase mode (O(2)+/O(3)-) and the secondary phases.…”

Characterization of Co-Evaporated ${\rm SmBa}_{2}{\rm Cu}_{3}{\rm O}_{7}$ Coated Conductors by Polarized-Raman Scattering Spectroscopy

“…The peaks at and , which are the O-O out-of-phase bending (O(2)+/O(3)-) in the plane and the O(4) apical mode, respectively, are strong and sharp in comparison with other peaks. If the textured film has the -axis orientation, the O(2)+/O(3)-mode should be at the maximum intensity, whereas the O(4) apical mode should be at a minimum [5]. Therefore, we can infer that (d) is better aligned in the -axis than (a), (b), and (c).…”

“…Raman scattering spectroscopy is a powerful method for examining the above-mentioned effects. Polarized-Raman scattering spectroscopy is not only a useful tool for identifying phonon modes, cation disorder, secondary phases, and impurities in a REBCO-coated conductor [4], but it is also valuable for investigating the stoichiometry and microstructure [5].…”