Sr1−xKxSi1−yGeyO3−0.5x: a new family of superior oxide-ion conductors†
Abstract
Monoclinic SrMO3 (M = Si or Ge) contains (001) planes of M3O9 units of three corner shared MO4 coplanar complexes separated by close-packed planes of Sr2+ ions each coordinated, top and bottom, by three terminal oxygen on three different M3O9 units. Substitution of K+ for Sr2+ introduces terminal-oxygen vacancies that are either not accommodated by corner sharing with a neighboring M3O9 unit, apparently because of steric hindrance by the large Sr2+ and K+ ions, or are accommodated by a distortion that creates an interstitial mobile