Abstract
We have studied the electronic structure of BaPb1-xBixO3 and its changes across the composition-dependent metal-semiconductor transition using photoemission and O 1s x-ray-absorption spectroscopy. For the parent insulator BaBiO3, the peak-to-peak splitting of the Bi 6s band is found to be large, whereas, the minimum gap is much smaller, qualitatively consistent with the large (approximately 2 eV) optical gap of the direct type and the smaller (approximately 0.5 eV) transport gap of indirect type. Pb substitution for Bi induces new states of Pb 6s character outside the band gap of BaBiO3 and does not induce in-gap spectral weight unlike in cuprate superconductors; the splitting of the Bi 6s band is not significantly reduced by Pb substitution throughout the semiconducting region. Substituted Pb remains tetravalent in the semiconducting phase and does not supply the Bi-O network with extra holes, which explains the stability of the semiconducting phase up to the Pb content of approximately 65%. Nevertheless, the band gap collapses in the metallic region (x
Original language | English |
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Pages (from-to) | 16917-16925 |
Number of pages | 9 |
Journal | Physical review. B, condensed matter |
Volume | 48 |
Issue number | 23 |
Publication status | Published - 15 Dec 1993 |
Externally published | Yes |
Keywords
- RESONANT-PHOTOEMISSION
- STATES
- SUPERCONDUCTIVITY
- BABIO3
- BA1-XKXBIO3
- SYSTEM
- MODEL