Superconductivity in Bismuth Oxysulfide Bi sub( 4)O sub( )4S sub( 3)

Bismuth oxysulfide ..., which has recently been claimed to be an exotic superconductor (Tc=4.5 K), was investigated by magnetic susceptibility and electrical resistivity measurements as well as by electron probe microanalysis. Single-phase ... was successfully prepared by a high-pressure method, and its lattice parameters and normal-state resistivity, as well as the density of states at the Fermi level, were found to be comparable to those determined earlier. However, the observed superconductivity was most likely impurity-driven, strictly contradictory to the observations in ongoing experiments. The present results indicate that the superconductivity of ... does not truly reflect the bulk nature of the BiS2 layered phase, regardless of the manner in which ... is synthesized. We discuss possible superconducting impurities. (ProQuest: ... denotes formulae/symbols omitted.)