Figure 1: Structure and the sign of carriers in Sr_3−xSnO.

(a) Powder X-ray diffraction spectrum of a superconductive Sr_3−xSnO batch-A sample. The spectrum was taken at room temperature on a lightly crushed sample with Kapton film and vacuum grease protecting it from air. Some impurity peaks can be seen marked with asterisks. The inset compares the perovskite SrSnO₃ and antiperovskite Sr₃SnO, emphasizing the change in oxidation states: Sr²⁺ corresponds to Sn⁴⁻, Sn⁴⁺ to O²⁻, and O²⁻ to Sr²⁺. (b) Hall coefficient measured as a function of temperatures showing hole-like carriers for a batch-A sample.