Superconductivity in (Ba,K)SbO(3)

(Ba,K)BiO(3) constitute an interesting class of superconductors, where the remarkably high superconducting transition temperature T(c) of 30 K arises in proximity to charge density wave order. However, the precise mechanism behind these phases remains unclear. Here, enabled by high-pressure synthesis, we report superconductivity in (Ba,K)SbO(3) with a positive oxygen–metal charge transfer energy in contrast to (Ba,K)BiO(3). The parent compound BaSbO(3−δ) shows a larger charge density wave gap compared to BaBiO(3). As the charge density wave order is suppressed via potassium substitution up to 65%, superconductivity emerges, rising up to T(c) = 15 K. This value is lower than the maximum T(c) of (Ba,K)BiO(3), but higher by more than a factor of two at comparable potassium concentrations. The discovery of an enhanced charge density wave gap and superconductivity in (Ba,K)SbO(3) indicates that strong oxygen–metal covalency may be more essential than the sign of the charge transfer energy in the main-group perovskite superconductors.