Reversible phase transition and switchable dielectric behaviors triggered by rotation and order-disorder motions of crowns

Abstract

Solid-to solid-state reversible phase transitions are widely used in switchable dielectrics, ferroelectrics, piezoelectrics, and pyroelectric and non-linear optical materials. Herein we report a new crown ether clathrate, [Habf-(18-crown-6)] [PF] (Habf = p-ammonium benzene formamide) which shows an interesting reversible phase transition near room temperature (263 K). X-ray single crystal diffraction analysis shows that the synergetic rotation motion between the 18-crown-6 crown ethers and the order-disorder motions of both hexafluorophosphate guest anions and 18-crown-6 crown ether host molecules lead to the phase transition. This reversible phase transition is confirmed by an evident thermal anomaly behavior around 263 K. The apparent step-like dielectric change around the phase transition indicates that it has potential application in dielectric switches.

A Narrow Bandgap of 2D Ruddlesden‐Popper Bilayer Perovskite with Giant Entropy Change and Photoluminescence

“…For most solid materials with reversible phase transitions, especially first‐order phase transitions, there are usually significant thermal anomalies near the phase transition temperature, including changes in entropy, enthalpy, specific heat capacity (C p ), etc [16] . DSC measurement can be used to measure the endothermic or exothermic phenomenon in the reversible phase transition process [17] .…”

Nonlinear Optical Responsive Molecular Switches

“…Similarly, solid-solid-state reversible phase transitions are widely used in the switchable dielectric, ferroelectric, piezoelectrical, and pyroelectrical and NLO materials. For instance, Yi [61] [57]; American Chemical Society, 2001).…”

“…Several demonstrations of integrated graphene-based modulators, switches, detectors, and nonlinear devices have been reported [63]. [61]; Royal Society of Chemistry, 2013).…”

“…Rotaxanes have, therefore, both molecular and supramolecular character: molecular because the components are held together mechanically and can be unlinked only by breaking strong covalent bonds; supramolecular because of the presence of weak noncovalent interactions[60].Similarly, solid-solid-state reversible phase transitions are widely used in the switchable dielectric, ferroelectric, piezoelectrical, and pyroelectrical and NLO materials. For instance, Yi[61] reported a new crown ether clathrate, [Habf-(18crown-6)1.5] + [PF6] − (Habf = p-ammonium benzene formamide) synthesis scheme as shown in Figure 8, which showed an interesting reversible phase transition and…”

“…Figure 8. The preparation of [Habf-(18-crown-6)1.5] + [PF6] − (Habf = p-ammonium benzene formamide) (Adopted from[61]; Royal Society of Chemistry, 2013).…”