Order−Disorder Antiferroelectric Phase Transition in a Hybrid Inorganic−Organic Framework with the Perovskite Architecture

Abstract

[(CH₃)₂NH₂]Zn(HCOO)₃, 1, adopts a structure that is analogous to that of a traditional perovskite, ABX₃, with A = [(CH₃)₂NH₂], B = Zn, and X = HCOO. The hydrogen atoms of the dimethyl ammonium cation, which hydrogen bond to oxygen atoms of the formate framework, are disordered at room temperature. X-ray powder diffraction, dielectric constant, and specific heat data show that 1 undergoes an order−disorder phase transition on cooling below ∼156 K. We present evidence that this is a classical paraelectric to antiferroelectric phase transition that is driven by ordering of the hydrogen atoms. This sort of electrical ordering associated with order−disorder phase transition is unprecedented in hybrid frameworks and opens up an exciting new direction in rational synthetic strategies to create extended hybrid networks for applications in ferroic-related fields.