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New Superconductors Containing Copper Oxides

IP.com Disclosure Number: IPCOM000037641D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Olson, BL: AUTHOR [+3]

Abstract

Copper oxide containing superconductors, such as the La2-xSrxCuO4 and REBa2Cu3O9-x (RE is Y and most other rare earths), have been shown to have high transitions. As of now the mechanism responsible for these high transition temperatures is not known and there is no generally accepted theory explaining why these copper oxides are unique. The transition temperature is directly related to the copper (III) concentration.

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New Superconductors Containing Copper Oxides

Copper oxide containing superconductors, such as the La2-xSrxCuO4 and REBa2Cu3O9-x (RE is Y and most other rare earths), have been shown to have high transitions. As of now the mechanism responsible for these high transition temperatures is not known and there is no generally accepted theory explaining why these copper oxides are unique. The transition temperature is directly related to the copper (III) concentration.

A series of oxides in the system La2-xSrxCuO4 were prepared where x was varied between 0.08 and 0.25; also several YBa2Cu3O9-x samples were prepared. Although structurally somewhat different, both these materials have the copper in an octahedral-like environment. The superconducting transition temperatures of these materials were measured and the samples were then analyzed for total copper and for copper (III) by a method where the Cu (III) oxidizing power with respect to Fe (II) was measured. By adding a known amount of standardized Fe (II) solution to the dry sample to reduce Cu (III) to Cu
(II), a portion of the Fe (II) is oxidized. The unused Fe (II) is titrated with standardized ceric (IV) solution. It is important that all standard solutions are prepared free from sulfate to prevent the precipitation of barium.

Plotting the Cu (III) concentration vs. the superconducting transition temperature Tc shows that there is a linear relationship between Tc and Cu (III). The fact that the Y-Ba-Cu-O material i...