An Order-Disorder Type High-Temperature Multiaxial Supramolecular Ferroelectric

Much progress has been witnessed in exploring host-guest type ferroelectrics represented by ammonium-crown ether compounds. However, the major obstacles in expanding their promising applications in nonvolatile memory elements, capacitors, and sensors are relatively low Curie temperature (T-c) and uniaxial attribute. Herein, by screening different organic cations and inorganic anions to assemble with 18-crown-6 molecule, it is found that a new ammonium-crown ether inclusion ferroelectric 1, [(ATHTP)(18-crown-6)]BF4 (ATHTP = protonated 4-aminotetrahydrothiopyran), undergoing a ferroelectric phase transition at a much higher T-c of 392 K which is comparable to BaTiO3 (T-c = 393 K). Notably, the distinct symmetry breaking, that is, 4/mmmFmm2, leads to a biaxial ferroelectric with four equivalent directions of polarization. Such high T-c and multiaxial nature are rare in existing crown ether-based ferroelectrics. This work can help the exploration of high-T-c multiaxial ferroelectrics toward further device applications.