Superconducting energy gap in bapb1-xbixo3 determined from point-contact tunneling

Electron tunneling measurements have been performed on single crystals of BaPb1-xBixO3 with various values of x. The observed density of states in the superconducting state can well be described by the broadened BCS density of states proposed by Dynes et al. The ratio [formula ommitted] increases with increasing the Bi concentration of x, suggesting the increase of electron-phonon interactions, and saturates at around [formula ommitted] The values of [formula ommitted] in the saturated region coincide with the BCS value.