Structural Chemistry and Magnetic Properties of the BaMn_0.4Co_0.6O_2.83 Hexagonal Perovskite

Abstract

The complete structural characterization of the hexagonal cobaltite BaMn0.4Co0.6O2.83 has been performed by combining high-resolution transmission electron microscopy and electron and neutron diffraction. The structure is closely related to the 12H (cc‘chhh)2 with oxygen deficient cubic c‘-BaO2 layers. This framework forms a laminar structure in which tetramers of face-sharing octahedra occupied by manganese and cobalt are connected by corners to two tetrahedral layers mostly occupied by cobalt. A magnetic study shows only the presence of short-range magnetic interactions indicating that there are no interactions between the tetramers through the tetrahedral layers, thus impeding the three-dimensional magnetic ordering of the system. A spin-glass-like state was found to be compatible with the observed phenomenology.

Synthesis and crystal structure of a new hexagonal perovskite 7H-Ba7Li1.75Mn3.5O15.75with Mn4+/Mn5+charge distribution

“…5). Interestingly, the stabilisation of this compound was shown to be likely due to Mn/Co ordering in the octahedral and tetrahedral sites, respectively (disorder in Mn/Co results in the well-known 5H 33 and 12H 34 polytypes), Fig. 1.…”

Structures and Microwave Dielectric Properties of Ba[Ti1−x(Co0.5W0.5)x]O3 (x = 0.40–0.90) Perovskite Ceramics

“…All diffraction spots are sharp and no apparent streaking along the c * axis is observed. No sign of disorder is observed by SAED . Thus, an interesting phase transition from cubic to hexagonal and then to cubic double perovskite, with increasing x , was observed.…”

“…No sign of disorder is observed by SAED. 4,5,26 Thus, an interesting phase transition from cubic to hexagonal and then to cubic double perovskite, with increasing x, was observed.…”

New 10H perovskites Ba5Ln1−xMn4+yO15−δ with spin glass behaviour

“…Many doped BaM x Mn 1Àx O 3 systems have been explored, for example, with M ¼ Ca, 6,7 Ti, 8,9 Fe, 10,11 Co, 12,13 Ru, 14,15 Ir, 16 In, 17,18 and rare earths Ln. [19][20][21][22][23] This led to the discovery of a range of Mcation ordered 10H perovskites Ba 5 26 The Ba 5 MMn 4 O 15 10H perovskite structure consists of close packed BaO 3 layers in a (cchhh) 2 sequence.…”