Switchable Dielectric Behaviors, Heat Anomalies and Ferroelastic Property of [Zn(en)₃]SO₄

Abstract

Investigations on reversible phase transition of coo‐rdination compounds have attracted much interest because they are promised to have wide application on energy storage, temperature controlling, data communication, ferroelastic and ferroelectric materials. Here we report the ferroelastic property, dielectric and heat anomalies of [Zn(en)3]SO4, 1 (en=ethylene diamine).1undergoes two sequential reversible phase transitions. The firestone occurs in the vicinity of 134 K, attributing to the order‐disordered motion of SO42−ions. The second one happens at 202 K, which origins form the symmetry improvement in the trigonal crystal system. Its switchable dielectrical bistability between high and low dielectric states accompanying with large entropy changes (ΔS=10.18 J⋅mol−1⋅K−1) for the phase transitions was confirmed by dielectric and differential scanning calorimetry (DSC) measurements.

A series of dynamic single crystals of [MII(en)3]SO4 (M = Ni, Mn, and Cd) shows tunable dielectric properties and anisotropic thermal expansion

“…The small dielectric switchings in these compounds are similar to the reported compound [Zn II (en) 3 ]SO 4 that undergoes the same P 3̄1 c to P 3̄ phase transition. 54 However, the dielectric switching in compound 2 is distinctly different from compounds 1 and 3 . As shown in Fig.…”

“…S3, ESI †). [51][52][53][54] The SO 2À 4 and complex cations are alternately arranged in the crystals and connected through N-H⋯O hydrogen bonds and electrostatic interactions. In the RTP, these compounds crystallize in a trigonal crystal system with the space group of P3 ˉ1c (No.…”

Reversible Structural Phase Transition and Dielectric Switches Induced by Disordering‐Ordering Motion of Tetrachloroferrate (III) Anions

“…According to documented mechanism of the structural phase transition, they can roughly be classified as displacement motion type, hydrogen bond shift type and ordering‐disordering motion type. In particular the ordering‐disordering motion type especially containing AX 4 anions (A=central atoms, L=auxiliary atoms) structure of phase transition materials exhibits significant advantages and become one of the hot topics in structural phase transition materials which include various kinds of anions such as ReO 4 2− , SeO 4 2− , ClO 4 − , BF 4 − , PO 4 3− et al ,…”

“…However, to our knowledge, few literatures document another special type of AX 4 metal structural anions, such as AuCl 4 − , FeCl 4 − , and ZnCl 4 2− etc ,…”