Investigation of Structural Phase Diagram and Superconductivity Mechanism in New Perovskite Antimonates

We propose elastic neutron powder diffraction experiments on new perovskite antimonates (Ba,K)SbO3. Recently, we confirmed that heavily K doped antimonates become superconducting at Tc = 13 K. This superconductivity could primarily be understood by strong electron-phonon coupling of the material, which also gives rise to structural distortions and two distinct Sb-O bond lengths in un- and under-doped insulating compounds. By investigating the atomic structure and Sb-O bond length across the boundary of an insulator-to-superconductor transition, we can not only draw the complete structural phase diagram of these new antimonates, but also get an important clue to find their superconducting mechanism. These results will help understand the mechanism of high-Tc superconductivity in main-group oxide perovskites, and can be applied to a design principle of novel superconductors in the future.