Cationic perovskite superconductor from high-pressure synthesis

Quantum materials with unprecedented properties are often stabilized under high pressures. Here we present the discovery of superconductivity at T_c = 15 K in new perovskite antimonates Ba_1−xK_xSbO₃ (BKSO) synthesized at a high pressure of 12 GPa. The sibling perovskites Ba_1−xK_xBiO₃ (BKBO) are known as anionic high-T_c superconductors with even higher T_c = 30 K. The distribution of valence electrons onto the cations (Sb or Bi) and ligands (O) is slightly different in BKSO compared to BKBO. Metal-oxygen covalency is suggested to become more important in BKSO.