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 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.

Precursor evolution and growth mechanism of BTO/YBCO films by TFA—MOD process

“…The peak at ∼ 515 cm −1 appears at 750 • C, which is attributed to A1(TO) due to BTO and TiO 2 nanoparticle. [28,29] Accordingly, the peaks at ∼ 337 cm −1 , ∼ 495 cm −1 , ∼ 565 cm −1 , and ∼ 622 cm −1 are assigned to YBCO, [30,31] and the peak at ∼ 622 cm −1 , which is assigned to the Cu-O stretching vibration of YBCO, is the typical peak of orthorhombic YBCO, this indicates the formation of a relatively complete structure of copper and oxygen. The Raman scattering peaks imply that the YBCO presents relatively good crystallinity.…”

Effect of Variation Substitution of Nd and Eu on the Crystal Structure of Y-124 Superconductor (Y1-x-yNdxEuyBa2Cu4O8??)

“…Puncak transmitansi pada rentang bilangan gelombang 400-1010 cm -1 adalah daerah ikatan logam dan oksigen yang terdapat pada sampel, yang mengindikasikan daerah dari YBCO termasuk fase impuritas Y 2 BaCuO 5 dan BaCO 3 seperti yang terdapat pada Gambar 5. Adanya puncak transmitansi pada bilangan gelombang kisaran 690 cm -1 dan kisaran 856 cm -1 menandakan adanya ikatan karbonat, dimana pita tersebut diindikasikan dengan BaCO 3 yang menandakan sampel mengandung pengotor dari BaCO 3 seperti yang diperlihatkan pada Gambar 5 [21,23,24]. Pada Gambar 5 dapat dilihat, pada bilangan gelombang kisaran 470 dan 644 cm -1 terdapat puncak transmitansi yang menandakan terdapatnya ikatan dari YBCO.…”

Synthesis and Physicochemical Properties of Nd‐, Sm‐, Eu‐Based Cuprate High‐Temperature Superconductors

“…[24] The inclusions of BaCuO 2 can be observed as a group of modes in Raman spectrum above 600 cm À1 , while a deficiency in oxygen leads to the activation of disorder modes located both near 240 cm À1 and above 600 cm À1 . [25] It should be noticed, that superconducting orthorhombic LREBa 2 Cu 3 O 7Àx structure is characterized by relatively high density of free carriers and therefore penetration of the sample by excitation laser beam is rather low, hence the intensities of Raman spectra are also very weak.…”