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Title: On-line characterization of YBCO coated conductors using Raman spectroscopy methods.

Abstract

The use of Raman spectroscopy for on-line monitoring of the production of superconducting YBa2Cu3O6+X (YBCO) thin films on long-length metal tapes coated with textured buffer layers is reported for the first time. A methodology is described for obtaining Raman spectra of YBCO on moving tape exiting a metal-organic-chemical-vapor-deposition (MOCVD) enclosure. After baseline correction, the spectra recorded in this way show the expected phonons of the specific YBCO crystal orientation required for high supercurrent transport, as well as phonons of non-superconducting second-phase impurities when present. It is also possible to distinguish YBCO films that are properly textured from films having domains of misoriented YBCO grains. An investigation of the need for focus control on moving tape indicated that focusing of the laser on the surface of the highly reflective YBCO films exiting the MOCVD enclosure tends to produce aberrant photon bursts that swamp the Raman spectrum. These photon bursts are very likely a consequence of optical speckle effects induced by a combination of surface roughness, crystallographic texture, and/or local strain within the small grain microstructure of the YBCO film. Maintaining a slightly out-of-focus condition provides the best signal-to-noise ratio in terms of the obtained Raman spectra. In addition to examining movingmore » tape at the post-MOCVD stage, Raman spectra of the film surface can also be recorded after the oxygen anneal performed to bring the YBCO to the optimum superconducting state. Consideration is given to data processing methods that could be adapted to the on-line Raman spectra to allow the tagging of out-of-specification tape segments and, at a more advanced level, feedback control to the MOCVD process.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
EE
OSTI Identifier:
914897
Report Number(s):
ANL/CMT/JA-58131
Journal ID: ISSN 0003-7028; APSPA4; TRN: US200817%%1
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Appl. Spectrosc.; Journal Volume: 61; Journal Issue: 4 ; Apr. 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
36 MATERIALS SCIENCE; YTTRIUM OXIDES; BARIUM OXIDES; COPPER OXIDES; RAMAN SPECTRA; RAMAN SPECTROSCOPY; ON-LINE MEASUREMENT SYSTEMS

Citation Formats

Maroni, V. A., Reeves, J. L., Schwab, G., Chemical Engineering, and SuperPower, Inc.. On-line characterization of YBCO coated conductors using Raman spectroscopy methods.. United States: N. p., 2007. Web. doi:10.1366/000370207780466208.
Maroni, V. A., Reeves, J. L., Schwab, G., Chemical Engineering, & SuperPower, Inc.. On-line characterization of YBCO coated conductors using Raman spectroscopy methods.. United States. doi:10.1366/000370207780466208.
Maroni, V. A., Reeves, J. L., Schwab, G., Chemical Engineering, and SuperPower, Inc.. Sun . "On-line characterization of YBCO coated conductors using Raman spectroscopy methods.". United States. doi:10.1366/000370207780466208.
@article{osti_914897,
title = {On-line characterization of YBCO coated conductors using Raman spectroscopy methods.},
author = {Maroni, V. A. and Reeves, J. L. and Schwab, G. and Chemical Engineering and SuperPower, Inc.},
abstractNote = {The use of Raman spectroscopy for on-line monitoring of the production of superconducting YBa2Cu3O6+X (YBCO) thin films on long-length metal tapes coated with textured buffer layers is reported for the first time. A methodology is described for obtaining Raman spectra of YBCO on moving tape exiting a metal-organic-chemical-vapor-deposition (MOCVD) enclosure. After baseline correction, the spectra recorded in this way show the expected phonons of the specific YBCO crystal orientation required for high supercurrent transport, as well as phonons of non-superconducting second-phase impurities when present. It is also possible to distinguish YBCO films that are properly textured from films having domains of misoriented YBCO grains. An investigation of the need for focus control on moving tape indicated that focusing of the laser on the surface of the highly reflective YBCO films exiting the MOCVD enclosure tends to produce aberrant photon bursts that swamp the Raman spectrum. These photon bursts are very likely a consequence of optical speckle effects induced by a combination of surface roughness, crystallographic texture, and/or local strain within the small grain microstructure of the YBCO film. Maintaining a slightly out-of-focus condition provides the best signal-to-noise ratio in terms of the obtained Raman spectra. In addition to examining moving tape at the post-MOCVD stage, Raman spectra of the film surface can also be recorded after the oxygen anneal performed to bring the YBCO to the optimum superconducting state. Consideration is given to data processing methods that could be adapted to the on-line Raman spectra to allow the tagging of out-of-specification tape segments and, at a more advanced level, feedback control to the MOCVD process.},
doi = {10.1366/000370207780466208},
journal = {Appl. Spectrosc.},
number = 4 ; Apr. 2007,
volume = 61,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
}
  • Raman microprobe spectroscopy and scanning electron microscopy were used to study the initial nucleation and growth of YBCO in thick precursors by the BaF2 ex situ process. For quenched films of 2 mum thickness, the data indicate a low density of c-axis nuclei near the substrate, apparently due to a reduced oxygen concentration deep inside the precursor layer. Significant non c-axis growth was also observed; the majority of this material nucleates away from the substrate. Measurement of the conversion rate by in situ XRD for films in the range 0.2-2 mum suggest a weak thickness dependence.
  • Inclined substrate deposition (ISD) is an effective method for rapid fabrication of high-quality template layers for YBCO-coated conductors. We have deposited biaxially textured ISD-MgO films on flexible metallic tapes in a reel-to-reel system by electron-beam evaporation at rapid deposition rates, 2-10 nm{center_dot}s-1. Strontium ruthenium oxide (SRO) buffer and YBCO films were grown by pulsed laser deposition (PLD). Pole figure analysis of a meter-long ISD-MgO tape was carried out by X-ray diffraction using a Bruker's D8 DISCOVER equipped with GADDS (general area detection diffraction system). The c-axis of the ISD-MgO film was tilted away from substrate normal. A full-width at halfmore » maximum (FWHM) of {approx_equal}10 deg. was observed from the {phi}-scan of the MgO (002) diffraction measured on samples deposited with 35 deg. inclination angle. Surface morphology measured by atomic force microscopy revealed a roof-tile shaped structure for the ISD-MgO films. Through the use of the SRO buffer, biaxial alignment in the YBCO film deposited on the ISD-MgO template was improved. The {phi}-scan FWHM was 5.8 deg. for the YBCO (005) diffraction. We have measured the critical transition temperature Tc = 91 K and transport critical current density Jc >1.6x106 A{center_dot}cm-2 at 77 K in self-field on a SRO-buffered YBCO film grown with ISD-MgO architecture.« less
  • The Rolling-Assisted Biaxially Textured Substrates (RABiTS) process has been identified as one of the leading candidates for the fabrication of high performance YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) coated conductors. The RABiTS process uses standard thermomechanical processing to obtain long lengths of flexible, biaxially oriented substrates with smooth surfaces. The strong biaxial texture of the metal is then transferred to the superconductor by the deposition of intermediate oxide buffers that serve both as a chemical and structural buffer. The typical three-layer RABiTS architecture consists of an e-beam Y{sub 2}O{sub 3} seed, sputtered YSZ barrier and a sputtered CeO{sub 2} cap layer.more » Chemical solution deposition of buffer layers offers potential cost advantage relative to physical vapor deposition (PVD) processes. Our main goal of this study is to develop simplified buffer architectures and demonstrate high J{sub c} Metal-Organic Deposition (MOD)-YBCO films on all-MOD buffers. La{sub 2}Zr{sub 2}O{sub 7} (LZO)/CeO{sub 2} buffers have been identified as potential candidates for this study. MOD-YBCO films with a critical current, I{sub c} of 212 A/cm have been achieved on MOD-LZO seeds with sputtered YSZ and CeO{sub 2} cap layers. In addition, MOD-YBCO films with a critical current, I{sub c} of 140 A/cm have been achieved on all MOD buffers of LZO/CeO{sub 2} for the first time. This offers a potential toward fabrication of lower cost YBCO coated conductors.« less
  • A solution processing technique was used to deposit an epitaxial Y2O3 film on (001)[100] cube textured Ni tapes for YBa2Cu3Ox (YBCO) coated conductors manufacturing. The cube texture was developed in Ni by a conventional thermo-mechanical process. A precursor solution of yttrium 2-methoxyethoxide in 2-methoxyethanol was spin-coated on the Ni substrate. The as-deposited amorphous film was thermally treated at 1100 deg. C in a flowing Ar+4%H2 gas mixture. The {theta}-2{theta} X-ray spectra revealed predominantly (001) reflections, indicating a high degree of out-of-plane orientation. Pole figures for the (222) Y2O3 reflections demonstrate a single in-plane texture. The out-of-plane and in-plane epitaxial relationshipmore » is [400]Y2O3//[200] Ni and [110]Y2O3//[100] Ni, respectively. The full-width-half-maximum (FWHM) of the {omega}-scans and {phi}-scans is 6 deg. and 11 deg. , respectively.« less