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Title: Growth and charaterisation of multilayer YBCO coated conductors on curved surfaces
Author: Cheung, Yim Lui
ISNI:       0000 0001 3543 4640
Awarding Body: The University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2005
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Multilayers of STO/YBCO thin films on Ce02/YSZ/CeO2 buffered curved Nibased rolling-assisted biaxially textured substrates (RABiTS) have been grown successfully by pulsed laser deposition in order to demonstrate the feasibility of fabricating an in situ multi-turn superconducting coil on a cylindrical heated former by continuous deposition of sequential layers of superconductor and insulator. Such an approach would offer a radical alternative to the conventional winding of coils from pre-formed long lengths of wires and tapes. AC susceptibility, X-ray diffraction (θ - 20 ω - scans, ψ - scans), scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) were used to characterise the superconducting, crystallinity, morphology and microtextural properties of the grown samples. The microstructure and chemical analysis of the interfaces of the curved samples were further investigated by cross-sectional transmission electron microscopy (XTEM) and scanning transmission electron microscopy (STEM). The superconducting and crystallographic properties of the curved composite were similar to those achieved on flat surfaces. The optimum thickness of each YBCO layer in the multilayer architecture was below I gm on a buffered curved surface. In the multilayer structure of six YBCO layers insulated by six STO layers (STO/YBCO)6 on a buffered curved surface, biaxial texture can be still transmitted from the substrate to all the layers and all the YBCO layers had c-axis orientation. Moreover, no interfacial diffusion or chemical reaction was observed at all the interfaces of the multilayer. However, defects such as pores and outgrowths were commonly found which affected the superconducting properties of the curved samples.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available