The electronic structure of ${\mathrm{Ba}}_{1\mathrm{-}\mathit{x}}$${\mathrm{K}}_{\mathit{x}}$${\mathrm{BiO}}_3$ has been studied by photoemission spectroscopy. With increasing x, the spectra are generally shifted towards the Fermi level (${\mathit{E}}_{\mathit{F}}$), indicating a downward shift of ${\mathit{E}}_{\mathit{F}}$ due to hole doping. The magnitudes of the shifts, however, are substantially smaller than those predicted by band-structure calculations. In the cubic metallic phase, although band-structure calculations on the cubic structure predict the density of states (DOS) to show a peak at or close to ${\mathit{E}}_{\mathit{F}}$, the photoemission intensity decreases towards ${\mathit{E}}_{\mathit{F}}$, suggesting that the splitting of the Bi 6s band persists and results in a pseudogap behavior. We propose that the suppression of the DOS peak at ${\mathit{E}}_{\mathit{F}}$ is caused by dynamical lattice distortion: The DOS peak predicted for the cubic structure presumably induces the lattice instability, leading to the dynamical lattice distortion.

• Received 16 May 1994

DOI:https://doi.org/10.1103/PhysRevB.50.13674