Structure and magnetic properties of Ba5Ce1.25Mn3.75O15, a new 10H-polytype in the Ba–Ce–Mn–O system

Based on the peculiar magnetic properties that are observed in pseudo one-dimensional manganites, we decided to synthesize the new Ba5Ce1.25Mn3.75O15 compound. The preparation was performed by solid state reaction in air at about 1350 °C, for which we found that the compound crystallizes in a hexagonal symmetry with space group P63/mmc (No-194) and cell parameters a=b=5.7861(2) Å and c=23.902(1) Å. The structural description was correlated with neutron diffraction and bond valence calculations, confirming the presence of Ce4+ and Mn4+ segregated in the different crystallographic positions. Ba5Ce1.25Mn3.75O15 displays evidence for strong AFM couplings already set at room temperature. The main arrangement of Mn4+ in magnetically isolated tetramers of face-sharing octahedra is responsible for a metamagnetic-like transition around 50 K.