Electronic structure of Ba Pb 1 − x Bi x O 3

摘要: Electronic-structure calculations have been carried out for representative members of the $\mathrm{Ba}{\mathrm{Pb}}_{1\ensuremath{-}x}{\mathrm{Bi}}_{x}{\mathrm{O}}_{3}$ alloy series with use self-consistent, scalar-relativistic, linear augmented plane-wave (LAPW) method and virtual-crystal approximation. The study includes LAPW high-temperature cubic ($x=0,0.3, 1$) as well room-temperature tetragonal ($x=0.3$) monoclinic ($x=1$) phases. results exhibit nearly-rigid-band---like behavior feature a ten-band $\mathrm{O}(2p)\ensuremath{-}[\mathrm{Pb}(6s),\mathrm{Bi}(6s)]$ complex near ${E}_{F}$ containing pair broad (\ensuremath{\sim}16 eV) $\ensuremath{\sigma}$-bonding $2p\ensuremath{-}6s$ subbands that are approximately centered on nonbonding O $2p$ states. $6s\ensuremath{-}2p$ band overlap metallic properties predicted all $x$ in phase. principal features structure survive distortion, predicting nearly spherical Fermi surface low density states at concentration range $0.05\ensuremath{\le}x\ensuremath{\le}0.30$ where superconductivity (${T}_{c}\ensuremath{\approx}13$ K) is observed. A strong Fermi-surface instability shown to occur terminal BaBi${\mathrm{O}}_{3}$ compound, explaining both stability phase its semiconducting properties.