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Structure refinements of superconducting and nonsuperconducting La 1.82 Ca 1.18 Cu 2 O 6 ± δ from neutron-diffraction data

Structure refinements of superconducting and nonsuperconducting La 1.82 Ca 1.18 Cu 2 O 6 ± δ from... The crystal structures of superconducting and nonsuperconducting La 1.82 Ca 1.18 Cu 2 O 6 ± δ synthesized under O 2 pressures of 400 and 2 atm were refined by Rietveld analysis of neutron-powder-diffraction data. These samples contained no impurities and their observed and calculated diffraction patterns were in excellent agreement. In both samples, Ca and La preferentially occupied, respectively, a 2a site in eightfold coordination and a 4e site in ninefold coordination; a slightly higher ordering was observed in the superconducting compound. An apical oxygen site was almost fully occupied. A trace of excess oxygen between two CuO 2 planes was detected in the superconducting compound. Cu-O(1) and Cu-O(2) bond lengths differed a little between the two samples. Increases in cation ordering and in interstitial oxygen might be important factors determining superconductivity in this system. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Physical Review B American Physical Society (APS)

Structure refinements of superconducting and nonsuperconducting La 1.82 Ca 1.18 Cu 2 O 6 ± δ from neutron-diffraction data

Kinoshita, K
Physical Review B , Volume 45 (10) – Mar 1, 1992
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Publisher
American Physical Society (APS)
Copyright
Copyright © 1992 The American Physical Society
ISSN
1095-3795
DOI
10.1103/PhysRevB.45.5558
Publisher site
See Article on Publisher Site

Abstract

The crystal structures of superconducting and nonsuperconducting La 1.82 Ca 1.18 Cu 2 O 6 ± δ synthesized under O 2 pressures of 400 and 2 atm were refined by Rietveld analysis of neutron-powder-diffraction data. These samples contained no impurities and their observed and calculated diffraction patterns were in excellent agreement. In both samples, Ca and La preferentially occupied, respectively, a 2a site in eightfold coordination and a 4e site in ninefold coordination; a slightly higher ordering was observed in the superconducting compound. An apical oxygen site was almost fully occupied. A trace of excess oxygen between two CuO 2 planes was detected in the superconducting compound. Cu-O(1) and Cu-O(2) bond lengths differed a little between the two samples. Increases in cation ordering and in interstitial oxygen might be important factors determining superconductivity in this system.

Journal

Physical Review B – American Physical Society (APS)

Published: Mar 1, 1992

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