Among ferroelectric crystals based on small molecules, plastic/ferroelectric crystals are currently receiving particular attention because they can be used as bulk polycrystals. Herein, we show that an ionic molecular ferroelectric crystal, guanidinium tetrafluoroborate, exhibits significant malleability and multiaxial ferroelectricity despite the absence of a plastic crystal phase. Powder samples of this crystal can be processed into transparent bulk crystalline plates either by pressforming or by melt-growing. The plates show high ferroelectric performance and related properties, demonstrating the largest hitherto reported spontaneous polarization for bulk polycrystals of small-moleculebased ferroelectrics. Owing to the ready availability of large-scale materials and processability into various bulk crystalline forms, this ferroelectric crystal represents a highly promising functional material that will boost research on diverse applications as bulk crystals.

Among ferroelectric crystals based on small molecules, plastic/ferroelectric crystals are currently receiving particular attention because they can be used as bulk polycrystals. Herein, we show that an ionic molecular ferroelectric crystal, guanidinium tetrafluoroborate, exhibits significant malleability and multiaxial ferroelectricity despite the absence of a plastic crystal phase. Powder samples of this crystal can be processed into transparent bulk crystalline plates either by pressforming or by melt-growing. The plates show high ferroelectric performance and related properties, demonstrating the largest hitherto reported spontaneous polarization for bulk polycrystals of small-moleculebased ferroelectrics. Owing to the ready availability of large-scale materials and processability into various bulk crystalline forms, this ferroelectric crystal represents a highly promising functional material that will boost research on diverse applications as bulk crystals.