Thermodynamic Property and Solid-State Molecular Dynamics of Cs2MnBr4·2H2O Crystal

The lattice constants of Cs2MnBr4·2H2O crystals grown by the slow evaporation method were determined by X-ray diffraction. The thermal stability of Cs2MnBr4·2H2O was investigated as a function of its H2O content, and an endothermic peak at 378 K (= Tp) obtained by differential scanning calorimetry (DSC) was related to the loss of 2H2O. Thermogravimetric analysis (TGA) and DSC results revealed that Cs2MnBr4·2H2O was transformed to Cs2MnBr4 at temperatures above the TP. In addition, from 133Cs magic angle spinning nuclear magnetic resonance (MAS NMR) results, one Cs site was observed at temperatures below the TP and two Cs sites above it. The change of the spin–lattice relaxation time T1ρ near TP is related to variations in the symmetry of the octahedral Cs+ environment consisting of four Br− ions and two water molecules, upon the loss of H2O.