The electronic structure of conducting and nonconducting forms of Bi2S
r2CaCu2O8+x ceramics was investigated by X-ray and X-ray photoelectron
spectroscopy. The conducting form differs in structure from the nonco
nducting one by the presence of oxygen and bismuth atoms in two oxidat
ion states as well as by pd-hybridization of O2p- and Cu3d-electrons i
n the valence band.