STRUCTURAL AND ELECTROMAGNETIC STUDY OF THIN AND THICK RE-Ba-Cu-O (RE = RARE EARTH) SUPERCONDUCTOR TAPES FABRICATED BY METAL ORGANIC CHEMICAL VAPOR DEPOSITION WITH AND WITHOUT BUFFER MODIFICATION
Khatri, Narayan D 1984-
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High temperature superconducting (HTS) tapes are being developed for a wide range of energy and magnetic applications. One of the challenges in their large scale deployment has been the cost associated with their fabrication. In this study, a high growth rate metal organic chemical vapor deposition (MOCVD) process is used to investigate the development of structural and electromagnetic properties of thick RE-Ba-Cu-O (REBCO, RE = rare earth) HTS films on biaxially-textured substrates. REBCO films are deposited as a thickness gradient (thickness ranging from 0 nm to almost 150 nm) on biaxially-textured flexible templates to understand structural properties development of films in their early stage of nucleation and growth. This work is then extended to fabricate thick films of almost 3 μm to achieve high critical currents. The thick films are deposited as a multi-layered structure and chemical-mechanical polishing of the deposited film has been employed following deposition of each layer to obtain suitable surface for subsequent REBCO layer’s deposition. This method has been shown to achieve tapes (2.86 μm thickness) with high engineering critical current density in the temperature range of 50 – 65 K and applied magnetic field range of 3 – 5 T. Another aspect of HTS films explored in this study is pre-fabrication of nanodefects which provides the opportunity to grow nanodefects independent of superconducting film growth. Metallic nanorods have been grown on biaxially-textured substrates by two methodologies namely, ‘electron beam-assisted deposition’ and ‘electrodeposition’ methods. Microstructural and electromagnetic properties of REBCO films with prefabricated metallic nanorods have been investigated.