A microRaman study of the structural properties of PLD high Tc superconducting thin films

Characterization of MBa2Cu3O7-x Thin Films by Raman Microspectroscopy

“…For example, one can (1) qualitatively gauge the relative amounts of in-plane textured versus tilted/aaxis grains from the relative intensities of the O2ϩ/O3Ϫ and O4 modes, [28][29][30][31] (2) distinguish MBCO/O from MBCO/T using the frequencies of the O4, Cu2, and O2ϩ/O3ϩ phonons, 16 and (3) obtain an estimate of the extent of oxygenation of MBCO (i.e., the value of x in MBa 2 Cu 3 O 7-x ) from the frequency of the O4 mode. [16][17][18][19] Coupling this capability with the well-established basis for identifying the relevant non-superconducting secondary phases that occur during precursor heat treatment to form MBCO films (e.g., CuO, Y 2 Cu 2 O 5 , Y 2 BaCuO 5 , BaCuO 2 , Ba 2 Cu 3 O 5 , etc. ), 37 it becomes demonstrably clear that Raman microscopy is a broadly useful methodology for interrogating MBCO coated conductors.…”

“…The most commonly utilized chemical/microstructural characterization techniques have included X-ray diffraction (see, e.g., List et al 12 ), scanning and transmission electron microscopy, 13,14 and Raman spectroscopy. [15][16][17][18][19][20] The interrogation of MBCO thin films using Raman spectroscopy has proven to be rapid, simple, versatile, and nondestructive (if properly done). Little or no sample preparation is required, and pertinent aspects of both phase chemistry and microstructure can be determined simultaneously (which goes beyond what one normally gleans from the other techniques commonly used to characterize coated conductors).…”

“…Little or no sample preparation is required, and pertinent aspects of both phase chemistry and microstructure can be determined simultaneously (which goes beyond what one normally gleans from the other techniques commonly used to characterize coated conductors). Raman scattering is sensitive to local chemical and physical phenomena and therefore lends itself to the detection of features that are not readily observable by other techniques, such as cation disorder, 16,18,[20][21][22][23][24] broken Cu-O chain structures, 16,17,24 and orthorhombic/tetragonal phase separation. [16][17][18][19]22 Also, it is useful in determining the presence of NSPs, such as barium cuprates, CuO, and M 2 BaCuO 5 (211 phase).…”

“…Raman scattering is sensitive to local chemical and physical phenomena and therefore lends itself to the detection of features that are not readily observable by other techniques, such as cation disorder, 16,18,[20][21][22][23][24] broken Cu-O chain structures, 16,17,24 and orthorhombic/tetragonal phase separation. [16][17][18][19]22 Also, it is useful in determining the presence of NSPs, such as barium cuprates, CuO, and M 2 BaCuO 5 (211 phase). 15,[25][26][27] Raman spectroscopy also supplies qualitative (and in some cases quantitative) information regarding out-ofplane texture (c-axis tilt and/or a-axis grain growth), [28][29][30][31] and can in an indirect way provide some information on the quality of in-plane epitaxy transmission.…”

“…15,[25][26][27] Raman spectroscopy also supplies qualitative (and in some cases quantitative) information regarding out-ofplane texture (c-axis tilt and/or a-axis grain growth), [28][29][30][31] and can in an indirect way provide some information on the quality of in-plane epitaxy transmission. 30,31 In addition to the above, Raman scattering is sensitive to the local oxygen content in MBCO [16][17][18][19]32 and to strain effects. 33 From all of the above, it is evident that Raman spectroscopy is a highly informative characterization method for the interrogation of MBCO films, one that could serve as a diagnostic tool for in situ characteriza-tion and process monitoring during MBCO coated conductor fabrication.…”