Order–disorder transition of a rigid cage cation embedded in a cubic perovskite

Abstract

The structure and properties of organic–inorganic hybrid perovskites are impacted by the order–disorder transition, whose driving forces from the organic cation and the inorganic framework cannot easily be disentangled. Herein, we report the design, synthesis and properties of a cage-in-framework perovskite AthMn(N3)3, where Ath+ is an organic cation 4-azatricyclo[2.2.1.02,6]heptanium. Ath+ features a rigid and spheroidal profile, such that its molecular reorientation does not alter the cubic lattice symmetry of the Mn(N3)3− host framework. This order–disorder transition is well characterized by NMR, crystallography, and calorimetry, and associated with the realignment of Ath+ dipole from antiferroelectric to paraelectric. As a result, an abrupt rise in the dielectric constant was observed during the transition. Our work introduces a family of perovskite structures and provides direct insights to the order–disorder transition of hybrid materials.

Tunable Dielectric Switching of (Quinuclidinium)[MnCl4] Hybrid Compounds

“…It is found that both order−disorder transformations of polar organic cations and weak displacements of inorganic frameworks make contributions to its switchable dielectric properties. 17,18 Particularly, recent scientific reports have revealed that for hybrids with spherical molecules 19 such as dabco (1,4diazabicyclo[2.2.2]octanium) or Q (quinuclidinium), a dynamic rotation or reorientation freezing involves interesting physicochemical properties and structural PT. 20,21 The search for good switchable dielectric materials is nontrivial, mainly due to satisfying simultaneously different requirements, e.g., attractive working temperature, sharp steplike phase transition, small-frequency dependence as well as easy and profitable technology.…”

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

“…As the frequency increases, the dielectric switching gradually shifts toward higher temperatures with a decrease in the dielectric constant, indicating a dielectric relaxation behaviour of this compound. The large dielectric anomaly and frequency dispersion observed in crystal 2 imply that the molecular dynamics of SO 2− 4 in this compound is significantly changed during the phase transition, 7,29,37,38,55 and the different dielectric properties of compounds 1 , 2 , and 3 suggest that the variation of metal centers with different radii efficiently controls the molecular motions of molecular rotors in this molecular rotor–stator system.…”

“…Dalton Transactions molecular dynamics of SO 2À 4 in this compound is significantly changed during the phase transition, 7,29,37,38,55 and the different dielectric properties of compounds 1, 2, and 3 suggest that the variation of metal centers with different radii efficiently controls the molecular motions of molecular rotors in this molecular rotor-stator system.…”

“…Therefore, tuning the dynamic motion of a rotating dipole in a molecular rotor-stator system is an effective way to control the dielectric switching of materials. [5][6][7]29,[34][35][36][37][38][39][40][41] In our previous study, we synthesized a series of dynamic single crystals of [M II (en) 3 ](ox) (M II = Fe II , Co II , Ni II , Zn II , and Cd II , en = ethylenediamine and ox 2− = oxalate dianion), in which the [M II (en) 3 ] 2+ complex cation and the ox 2− dianion serve as molecular stator and rotor, respectively. In response to the dynamic motion of ox 2− , these compounds show interesting shape transformations and anisotropic magnetic switching.…”

Sn1/3Na2/3Sn(OH)6 Perovskite with Sn4+/Na+ Disorder for Photocatalytic Degradation of 2,4-Dichlorophenol

“…It has a significant effect on electrons and phonons in solids, affecting their physicochemical properties. Accordingly, lattice disorder has received extensive attention in the thermoelectric, electrocatalysis, and photocatalysis fields. − For instance, in photocatalysis, it can be applied to modulate the bandgap of a material and photogenerated-carrier recombination.…”