Identifying the local structural units in La 0.5 Ba 0.5 MnO 2.5 and BaY 0.25 Fe 0.75 O 2.5 through the neutron pair distribution function

Neutron pair distribution function data are used to investigate the local structures of two oxygen deficient perovskites with simple cubic crystal structures. La_0.5Ba_0.5MnO_2.5 is found to have alternating layers of MnO₆ octahedra and MnO₄ tetrahedra, making it similar to other members of the La_1-xBa_xMnO_2.5 series with smaller x values which have brownmillerite crystal structures. Our fitting results suggest that La_0.5Ba_0.5MnO_2.5 is not locally …