Publication Date

1993

Document Type

Dissertation/Thesis

First Advisor

Dąbrowski, Bogdan

Degree Name

M.S. (Master of Science)

Department

Department of Physics

LCSH

High temperature superconductivity||Copper oxide superconductors||Superconductivity||Solid state chemistry

Abstract

The La[sub 2-x]Ca[sub 1+x]Cu[sub 2]O[sub 6+y] (0212) material, having the simplest double copper oxygen plane structure common to all high-T[sub c] superconductors, was synthesized in oxygen using pressures up to 600 bar and temperatures up to the melting point. Samples with 0 5 x < 0.5 synthesized in air usually contained a small amount of impurities and were not superconducting. Superconductivity was observed only for samples synthesized under high oxygen pressure and temperatures above 900°C. The range of single phase solid solutions depended on synthesis temperature and was the largest (0.1 £ x £0.3) at 1180°C. The crystal structure was studied by x-ray and neutron powder diffraction. The M(l) site was occupied by Ca atoms only, Ca substitution for La went into M(2) site. There was oxygen deficiency for samples synthesized in air. Oxygen content was increased after high pressure synthesis. The superconducting properties were determined by DC resistivity and AC susceptibility techniques. The highest T[sub c](10%) for a single-phase 0212 material was found to be about 60 K for a sample with x = 0.18, which was post-annealed in oxygen after high pressure synthesis.

Comments

Includes bibliographical references (pages [64]-67)

Extent

67 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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