Synthesis and atom-scale microstructure of Ba6Mn5O16

Layered manganate Ba6Mn5O16 was prepared by a traditional solid-state reaction method and its microstructure at atomic level was investigated in detail by means of high-resolution transmission electron microscopy (HRTEM). Although the sample shows, from the XRD data, a nearly single-phase n=5 layered Ba6Mn5O16 phase of the hexagonal Ban+1MnnO3n+1 homologous series, the presence of numerous structural defects, especially intergrowth faults of the hexagonal Ban+1MnnO3n+1 homologous series with different n in it, was revealed by HRTEM. Furthermore, a minor 2H BaMnO3 phase was also found to coexist with the layered Ba6Mn5O16 phase. These defects could have a correlation with the magnetic properties of the sample, i.e. the TN being very broad and the appearance of the Curie tail in the susceptibility.