Highest-T_c organic enantiomeric ferroelectrics obtained by F/H substitution

Abstract

(R)- and (S)-(N,N-dimethyl-3-fluoropyrrolidinium) iodide show the highest phase transition temperature (Tc) of 470 K among enantiomeric ferroelectrics.

Target Designing Phase Transition Materials through Halogen Substitution

“…How to chemically synthesize and obtain crystalline materials with high phase transition temperature is crucial concerning the practical applications. [17][18][19] From the point view of crystallography, the symmetry of the crystal structure is usually described using 32 point groups and 230 space groups, [20,21] and the solid-solid phase transition is always accompanied by the symmetry breaking, [22] which reveals the physical and/or mathematical characteristics of the phase transition. The symmetry breaking is essential for understanding phase transition behaviors of crystalline materials, especially for the hybrid organic and inorganic materials and electrolyte materials.…”

“…Those phase transition crystalline materials have broad applications in the fields of the photoelectric switch, [6–9] switchable dielectric equipment, [10–12] ferroelectric memory devices, [13–15] sensors, [16] etc . How to chemically synthesize and obtain crystalline materials with high phase transition temperature is crucial concerning the practical applications [17–19] . From the point view of crystallography, the symmetry of the crystal structure is usually described using 32 point groups and 230 space groups, [20,21] and the solid‐solid phase transition is always accompanied by the symmetry breaking, [22] which reveals the physical and/or mathematical characteristics of the phase transition.…”

H/F substitution for advanced molecular ferroelectrics

“…However, from the perspective of crystallography, the introduction of bulky substituents often changes the parent molecular crystal structure, which may result in vanished ferroelectricity. Because of the closest van der Waals radius and the most similar steric parameters between H and F atoms, monofluorination can ensure the minimum disruption of the crystal structure, but significantly change the physical and chemical properties [28][29][30][31]. Resembling the isotope effect, the substitution of an F atom can remarkably increase the T c .…”

Observation of Transition from Ferroelasticity to Ferroelectricity by Solvent Selective Effect in Anilinium Bromide

“…[5] Among them, the simple organic ammonium halides are of particular interest by their outstanding performances that can be comparable to and even surpass those of inorganic ferroelectrics.D iisopropylammonium bromide has been found as ah igh-temperature molecular ferroelectric with aspontaneous polarization (P s )of23mCcm À2 (close to that of BaTiO 3 )a nd high T c of 426 K( above that of BaTiO 3 ). [6] Diisopropylammonium chloride is also am olecular ferroelectric with ah igh T c of 440 K. [7] Moreover,b yi ntroducing chiral center in molecules,the organic ammonium halides can be optically active homochiral ferroelectrics,such as (R)-(À)-3-hydroxlyquinuclidinium halides, [8] and (R)-and (S)-N,Ndimethyl-3-fluoropyrrolidinium iodide, [9] which are multiaxial molecular ferroelectrics as well. Although great efforts have been made to extend attractive simple ferroelectric organic salts,h owever,t he ammonium halide ferroelectrics still remain very sparse.…”

“…Diisopropylammonium chloride is also a molecular ferroelectric with a high T c of 440 K [7] . Moreover, by introducing chiral center in molecules, the organic ammonium halides can be optically active homochiral ferroelectrics, such as ( R )‐(−)‐3‐hydroxlyquinuclidinium halides, [8] and ( R )‐ and ( S )‐ N , N ‐dimethyl‐3‐fluoropyrrolidinium iodide, [9] which are multiaxial molecular ferroelectrics as well. Although great efforts have been made to extend attractive simple ferroelectric organic salts, however, the ammonium halide ferroelectrics still remain very sparse.…”