Target Designing Phase Transition Materials through Halogen Substitution.

Abstract

Crystalline materials have received extensive attention due to their extraordinary physical and chemical properties. Among them, phase transition materials have attracted great attention in the fields of photovoltaic, switchable dielectric devices, and ferroelectric memories, etc. However, many of them suffer from low phase transition temperatures, which limits their practical application. In this work, we systematically designed crystalline materials, (TMXM)2 PtCl6 (X=F, Cl, Br, I) through halogen substitution on the cations, aiming to improving phase transition temperature. The resulting phase transition of (TMXM)2 PtCl6 (X=F, Cl, Br, I) get a significant enhancement, compared to the parent compound [(CH3 )4 N]2 PtCl6 ((TM)2 PtCl6 ). Such phase transition temperature enhancement can be attributed to the introduction of halogen atoms that increase the potential energy barrier of the cation rotation. In addition, (TMBM)2 PtCl6 and (TMIM)2 PtCl6 have a low symmetry and crystallize in the space group C2 /c and P21 21 21 , respectively. This work highlights the halogen substitution in designing crystal materials with high phase transition temperature.