In this chapter, we review the recent experimental work in emerging superconductors, i.e., bismuth chalcogenides, including the newly discovered BiS(e)2-based layered superconductors and some topological superconductor candidates. Their crystal structure and various physical properties are reviewed in detail, with the correlation between structure and superconductivity as the main clue throughout this chapter. Bi2OS2 is the simplest structure in Bi─O─S compounds and probably the parent compound of this series. Superconductivity emerges when carriers are introduced by intercalation or chemical substitution. The superconducting layer is extended to BiSe2 layer in LaO1−xFxBiSe2, which has an improved superconductivity. Moreover, the topological insulator Bi2Se3 can be turned into superconductors by intercalating metal atoms into van der Waals space, e.g., SrxBi2Se3, a potential topological superconductor, whose quantum oscillations reveal a possible topological surface state. The intermediate external pressure can efficiently suppress superconductivity, which reemerges when pressure is further increased, while Tc is nearly invariant in high-pressure region, indicating an unconventional pairing state.
Part of the book: Superfluids and Superconductors