Recent improvements in bulk properties of ceramic superconductors

Ceramic superconductors are being considered for uses ranging from large-scale applications such as the generation, transmission, and storage of electricity to small-scale applications such as electronic circuitry. These applications require that the electrical, mechanical, and chemical properties of superconductors meet certain specifications. The properties of superconductors are strongly influenced by each step of the processing procedure, which includes powder processing to form the superconductor powder, shape forming to produce bulk superconductors in convenient shapes, and finally an appropriate heat treatment to yield good superconducting properties. In this paper, the processing procedures for Y-Ba-Cu-O, Bi-Sr-Ca-Cu-O, Tl-Ca-Ba-Cu-O are reviewed. Improvements in the processing procedures, and the resulting improvements in the mechanical and electrical properties are discussed. In addition, several fabrication techniques are described which have produced bulk conductors having critical current densities approaching those of thin films