Year

1997

Degree Name

Doctor of Philosophy

Department

Department of Materials Engineering

Abstract

The aim of this study was to identify and explore possible ways to improve the critical current density of Bi-2212/Ag tapes. The work was divided into two parts: growth and characterisation of Bi-2212 crystals; and improvement of Bi-2212/Ag superconducting tapes. In the first part, the focus was on growing high quality Bi-2212 single crystals in order to gain knowledge in relation to the formation of Bi-2212 phase, the uptake and release of structural oxygen from B-2212 crystal structure, the relation between critical transition temperature and cation stoichiometry. Also, due to some uncertainty regarding the fundamental parameters of the Bi-2212 phase such as the higher critical field (Hcz), penetration depth (k) and coherence length (Q, good quality Bi-2212 single crystals were used for measurements of these parameters. The knowledge gained in the first part of this study was used in the second part as a basis for the design of new procedures to increase the critical current density of Bi- 2212/Ag tapes.

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