Synthesis, characterization and magnetic properties of a manganese (II) silicate containing frustrated S=5/2 zig–zag ladders

Abstract

The hydrothermal synthesis, structural characterization and magnetic properties of a manganese silicate with ideal formula of NaMn2Si3O8(OH) is reported. This compound is a synthetic analog to the naturally occurring mineral Serandite. The crystal structure comprises MnO6 octahedra and SiO4 tetrahedra. The MnO6 share four edges with neighboring octahedra forming double chains. These chains are connected by silicate chains Si3O8(OH) resulting in an open framework structure with six-member ring channels where sodium ions are located. From the magnetic point of view, the intra-chain exchange between neighboring S=5/2 manganese ions is weak, partly due to the distortion observed in the octahedra, but also due to the frustrated topology of the chain. A successful fitting of the magnetic susceptibility was obtained by considering a double chain numerical model with Monte Carlo derived empirical parameters.