Phase transition, dielectric switching property of an In (III)-based organic-inorganic hybrid compound: (C5H16N2)InBr5

An indium-based organic-inorganic phase transition material (C5H16N2)InBr5 (1) was synthesized by the reaction of In2O3 and 2, 2-dimethyl-1, 3-propanediamine in excess hydrobromic acid solution. Differential scanning calorimetry (DSC) measurement reveals that 1 experiences a first-order structural phase transition at Curie temperature Tc = 176 K. A step-like dielectric anomaly was recorded at around phase transition temperature. Further the variable-temperature single crystal X-ray diffraction indicates that the order-disorder transition of (C5H16N2)(2+) cation is the main factor drove the phase transition, changing from the non-centrosymmetric (NCS) space group of P2(1)2(1)2(1) to centrosyrnmetric (CS) space group Pnma upon heating. This finding paves the avenue to design and explore dielectric switching materials based on In-based organic-inorganic hybrid compounds.