Synthesis and characterization of MnCrO4, a new mixed-valence antiferromagnet

A new type of composite structure is described consisting of the todorokite-type [Mn6O12] framework with large square tunnels accommodating columnar fragments of the rock-salt structure. The crystal structure of the new todorokite-type [SrF0.8(OH)0.2]... The new todorokite-type [SrF0.8(OH)0.2]2.526[Mn6O12] compound represents a new type of composite structure consisting of the todorokite-type [Mn6O12] framework with large square tunnels accommodating columnar [SrF0.8(OH)0.2] fragments of the rock-salt structure. It demonstrates a much larger number of cations inside the tunnels in comparison with the known synthetic and natural marine todorokites.