Electronic structure of high-T/sub c/ Ba/sub 0. 6/K/sub 0. 4/BiO/sub 3/ by x-ray photoelectron spectroscopy

Journal Article · Wed Mar 01 00:00:00 EST 1989 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.39.4752· OSTI ID:6419133

Hegde, M S; Barboux, P; Chang, C C; Tarascon, J M; Venkatesan, T; Wu, X D; Inam, A

We have investigated the electronic structure of Ba/sub 1-//sub x/K/sub x/BiO/sub 3/ (0<0.4) by x-ray photoelectron spectroscopy. The Bi(4f) core levels show a normal valency of +3 as in Bi/sub 2/O/sub 3/ and we find no evidence for the disproportionation of Bi/sup 4+/ to Bi/sup 3+/ and Bi/sup 5+/. Instead, we find that BaBiO/sub 3/ has mixed valent O/sup 2-/ and O/sup 1-/ ions. As the potassium doping is increased, the binding energy of the O/sup 2-/ ions in the O(1s) photoelectron spectra steadily decreases from 529.7 to 528.8 eV. The effect of lowering the O(1s) binding energy is to raise the O(2p) band towards E/sub F/ and at the superconducting composition a finite density of O(2p) states is observed near E/sub F/. Similarly, the Ba(5p) binding energies decrease with potassium doping, indicating increased metallicity. The behavior of the O(1s), Ba(5p), and the valence band resembles that of all the cuprate superconductors and we conclude that in all these oxide superconductors, a hole in the (filled) O(2p) band is the carrier responsible for superconductivity, which predicts hole conduction in the Ba-K-Bi-O and Ba-Pb-Bi-O systems.

• Research Organization: Center for Ceramics Research, Rutgers University, Piscataway, New Jersey 08854
• OSTI ID: 6419133
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Vol. 39:7
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BARIUM OXIDES
ELECTRONIC STRUCTURE
SUPERCONDUCTIVITY
BISMUTH OXIDES
POTASSIUM OXIDES
BINDING ENERGY
HOLES
PHOTOELECTRON SPECTROSCOPY
QUANTITY RATIO
X RADIATION
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
BISMUTH COMPOUNDS
CHALCOGENIDES
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTROMAGNETIC RADIATION
ELECTRON SPECTROSCOPY
ENERGY
IONIZING RADIATIONS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
POTASSIUM COMPOUNDS
RADIATIONS
SPECTROSCOPY
360204* - Ceramics
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