Photoemission Studies of Electronic Structures of BaPb_1−xBi_xO₃

抄録

Photoemission spectra of BaPb_1−xBi_xO₃ are measured for x=0, 0.25, 0.3 and 0.6 by use of synchrotron radiation. A remarkable discrepancy from the results of band calculation is recognized. It is found that the O 2p_⊥ band has a high density of states (DOS) at binding energies (E_B) of 3.0∼3.5 eV. The DOS at the Fermi level (E_F) is found to be negligibly small in all samples. The E_B of the Pb 5d bands for x=0.3 and 0.6 are around 0.3 eV smaller than those for x=0. It is also found that the Ba 5p core levels shift to larger E_B by ∼0.3 eV with increasing x. The Bi 5d core levels have shown no additional structure besides the spin-orbit splitting, whereas the Pb 5d core spectra are remarkably distorted for x=0.3 and 0.6. These effects are discussed in regard to the charge transfer and the hybridization of electronic states.