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Electronic structure study of the formal oxidation states of thallium, lead, bismuth in the ASr sub 2 Ca sub n-1 Cu sub n O sub 2n+3 superconductors (A = Tl sub 0. 5 Pb sub 0. 5 , Tl sub 0. 5 Bi sub 0. 5 )

Journal Article · · Inorganic Chemistry; (USA)
DOI:https://doi.org/10.1021/ic00327a021· OSTI ID:6836740
; ;  [1]
  1. North Carolina State Univ., Raleigh (USA)
The formal oxidation states of Pb and Bi in the single rock salt layer superconductors ASr{sub 2}Ca{sub n{minus}1}Cu{sub n}O{sub 2n+3} (A = Tl{sub 0.5}Pb{sub 0.5}, Tl{sub 0.5}Bi{sub 0.5} n = 2,3) was examined by performing tight-binding band electronic structure calculations on the distorted AO{sub 3} layers and also molecular orbital calculations on the distorted AO{sub 6} octahedra. Results show that the most likely oxidation state of Pb is +4, and that of Bi is either +3 or +5. The similarities in the T{sub c} values of (Tl{sub 0.5}Pb{sub 0.5})Sr{sub 2}CaCu{sub 2}O{sub 7} and (Tl{sub 0.5}Bi{sub 0.5})Sr{sub 2}CaCu{sub 2}O{sub 7} suggest that the Bi atoms of (Tl{sub 0.5}Bi{sub 0.5})Ca{sub n{minus}1} Cu{sub n}O{sub 2n+3} are half in the +3 and half in the +5 oxidation states. Thus the Pb and Bi atoms of ASr{sub 2}Ca{sub n{minus}1}Cu{sub n}O{sub 2n+3} lower the copper oxidation state with respect to that of TlBa{sub 2}Ca{sub n{minus}1}Cu{sub n}O{sub 2n+3}. 9 refs., 3 figs., 1 tab.
DOE Contract Number:
FG05-86ER45259
OSTI ID:
6836740
Journal Information:
Inorganic Chemistry; (USA), Journal Name: Inorganic Chemistry; (USA) Vol. 29:2; ISSN 0020-1669; ISSN INOCA
Country of Publication:
United States
Language:
English