Local structural changes in lithium-doped YBa sub(2)Cu sub(3)O sub(y)

The structure of orthorhombic and tetragonal samples of lithium (Li)-doped YBa sub(2)Cu sub(3)O sub(y) has been determined by neutron powder diffraction measurements. The experiment shows that when the samples are synthesized in oxygen, Li substitutes for the copper of the CuO sub(2) planes. When th...

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Bibliographic Details
Published in:Physica. C, Superconductivity Superconductivity, 2000-01, Vol.333 (1), p.121-132
Main Authors: Maury, F, Nicolas-Francillon, M, Bouree, F, Ollitrault-Fichet, R, Nanot, M
Format: Article
Language:English
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Summary:The structure of orthorhombic and tetragonal samples of lithium (Li)-doped YBa sub(2)Cu sub(3)O sub(y) has been determined by neutron powder diffraction measurements. The experiment shows that when the samples are synthesized in oxygen, Li substitutes for the copper of the CuO sub(2) planes. When the samples are synthesized in air, a small fraction ( approximately 20%) of the Li substitutes for the copper of the Cu-O chains. Moreover, the best fits to the diffraction spectra, as well as the best overall understanding of a number of experimental observations, are obtained by assuming that each substitution of a Li for a Cu entails the loss of the neighbouring apical oxygen. This feature seems to be retained during the annealing in argon at 750 degree C, which transforms the crystallographic structure from orthorhombic to tetragonal.
ISSN:0921-4534