The first high-temperature multiaxial ferroelectric host-guest inclusion compound

A host-guest inclusion compound, 18-crown-6 oxonium tetrachloride-gallium(iii), was shown to undergo a 4/mmmFmm2-type ferroelectric phase transition with four crystallographically equivalent polarization directions at 337 K. To the best of our knowledge, this is the first host-guest inclusion compound shown to be a high-temperature multiaxial molecular ferroelectric.