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Superconducting Ceramics Fabricated by Glass Devitrification

IP.com Disclosure Number: IPCOM000050376D
Original Publication Date: 1982-Oct-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Gambino, RJ: AUTHOR

Abstract

Known ceramic methods for fabricating superconducting oxides of the type BaPb(1-x) Bi(x)0(3) are not suitable for the fabrication of complex shapes, such as coils.

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Superconducting Ceramics Fabricated by Glass Devitrification

Known ceramic methods for fabricating superconducting oxides of the type BaPb(1-x) Bi(x)0(3) are not suitable for the fabrication of complex shapes, such as coils.

A superconducting body (of BaPb(.7) Bi(.3) O(3), for example) of any shape is obtained through the preparation of a glass by melting together its constituents BaCO(3), PbO, Bi(2)O(3), B(2)O(3) and K(2)CO(3) and shaping the glass into its desired final shape by conventional methods of glass technology. The conversion of the glass to a superconducting body occurs during an annealing treatment in an oxygen ambient at a temperature near the softening point. This leads to the oxidation of the lead and bismuth to higher valence states. This devitrification and formation of the superconductive BaPb(1-x) Bi(x)O(3) occurs preferentially at the surface of the glass and is allowed to proceed until a continuous superconducting layer covers the entire surface. Enhancement of surface crystallization is possible by packing the glass in an ionic crystalline solid, such as BaCO(3) powder, during the annealing process.

Multiple superconducting filaments in the mass of a body are obtained by a two-draw process similar to the one used to fabricate glass microchannel plates. Bundles of drawn fibers are heated and drawn again to form a honeycomb array of smaller glass fibers with channels in between. The glass is then devitrified in an oxidizing ambient to form th...