Expanding the Ruddlesden–Popper Manganite Family: The n = 3 La3.2Ba0.8Mn3O10 Member
journal contributionposted on 05.11.2012, 00:00 by Joke Hadermann, Artem M. Abakumov, Alexander A. Tsirlin, Marina G. Rozova, Eleni Sarakinou, Evgeny V. Antipov
La3.2Ba0.8Mn3O10, a representative of the rare n = 3 members of the Ruddlesden–Popper manganites An+1MnnO3n+1, was synthesized in an evacuated sealed silica tube. Its crystal structure was refined from a combination of powder X-ray diffraction (PXD) and precession electron diffraction (PED) data, with the rotations of the MnO6 octahedra described within the symmetry-adapted mode approach (space group Cccm, a = 29.068(1) Å, b = 5.5504(5) Å, c = 5.5412(5) Å; PXD RF = 0.053, RP = 0.026; PED RF = 0.248). The perovskite block in La3.2Ba0.8Mn3O10 features an octahedral tilting distortion with out-of-phase rotations of the MnO6 octahedra according to the (Φ,Φ,0)(Φ,Φ,0) mode, observed for the first time in the n = 3 Ruddlesden–Popper structures. The MnO6 octahedra demonstrate a noticeable deformation with the elongation of two apical Mn–O bonds due to the Jahn–Teller effect in the Mn3+ cations. The relationships between the octahedral tilting distortion, the ionic radii of the cations at the A- and B-positions, and the mismatch between the perovskite and rock-salt blocks of the Ruddlesden–Popper structure are discussed. At low temperatures, La3.2Ba0.8Mn3O10 reveals a sizable remnant magnetization of about 1.3 μB/Mn at 2 K, and shows signatures of spin freezing below 150 K.