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Observation of superconductivity in (Y/sub 1-x/Ca/sub x/)Ba/sub 2/Cu/sub 3/O/sub 6/

Journal Article · · J. Solid State Chem.; (United States)
Substitution of Ca/sup 2 +/ for Y/sup 3 +/ in YBa/sub 2/Cu/sub 3/O/sub 6/ converts this tetragonal semiconductor into a tetragonal superconductor with a T/sub c/ of 50 K. Furthermore, the structure of (Y/sub 0.8/Ca/sub 0.2/)Ba/sub 2/Cu/sub 3/O/sub 6/, determined by neutron powder diffraction, is fully consistent with partial oxidation of the Cu(2)-O sheets, whereas the linear O-Cu(1)-O units do not undergo oxidation. Observation of a limited solid solubility for Ca/sup 2 +/ in this structure is attributed to a maximum allowed oxidation state for Cu(2). This implies that in the superconductor YBa/sub 2/Cu/sub 3/O/sub 7/ the Cu-O chains are responsible for the T/sub c/ of 90 K, whereas the Cu-O sheets alone produce superconductivity at 50 K in YBa/sub 2/Cu/sub 3/O/sub 6.5/.
Research Organization:
E. I. du Pont de Nemours and Co., Inc., Wilmington, DE (USA)
OSTI ID:
6182483
Journal Information:
J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Vol. 78:1; ISSN JSSCB
Country of Publication:
United States
Language:
English