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Effect of annealing in oxygen on the structure formation of Bi-Sr-Ca-Cu-O thin films

Journal Article · · Phys. Rev. B: Condens. Matter; (United States)

The structure, bonding, and T/sub c/ of Bi-Sr-Ca-Cu-O superconducting films, prepared by rf magnetron sputtering, changed systematically upon varying the annealing conditions in oxygen. The spacing between the double Bi-O layers decreased from 22 to 18 A and the degree of c-axis orientation became higher with the annealing. No change in the Bi core-level electron spectra with the annealing was observed. The Cu core-level electron spectra indicated an increase of the Cu valence with the annealing. The core-level electron spectra of Sr and Ca showed the possibilities of random distribution of the Ca and Sr atoms between the double Bi-O layers prior to annealing and exchanging their lattice sites in the Bi/sub 2/Sr/sub 2/Ca/sub 2/Cu/sub 3/O/sub y/ crystal structure after annealing. The zero-resistance temperature of the films was 10 K before annealing, and rose up to 96 K (midpoint 105 K) after annealing. The annealing favors both oxidation of Cu and ordering of Sr and Ca atoms within the unit cell of the 2:2:2:3 crystal structure.

Research Organization:
Central Research Laboratories, Matsushita Electric Industries, Moriguchi, Osaka 570, Japan
OSTI ID:
6479535
Journal Information:
Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 39:7; ISSN PRBMD
Country of Publication:
United States
Language:
English