Room-Temperature Ferroelectricity and Gigantic Dielectric Susceptibility on a Supramolecular Architecture of Phenazine and Deuterated Chloranilic Acid

Ferroelectricity and large dielectric constant at room temperature have been demonstrated for cocrystals of phenazine and anilic acids constructing supramolecular assemblies. Deuteration of the anilic acids gives rise to an increase by more than 50 K in the transition temperature, which exceeds room temperature for the deuterated chloranilic acid. At room temperature in air, the crystals show a clear polarization hysteresis with a small coercive field. Application of hydrostatic pressure and halogen substitution in the anilic acids bring about the structural effect on the transition temperature in a parallel way, whereas the deuterium substitution does this in a distinct way. The observed large deuteration effect cannot be elucidated by the geometric change of the hydrogen bond, which has been considered as the possible mechanism of ferroelectricity in the conventional hydrogen-bonded with double-well potential.

室温下，构建超分子组装体 (supramolecular assemblies) 的吩嗪 (phenazine) 与苯胺酸 (anilic acids) 共晶体 (cocrystals) 已被证实具备铁电性 (Ferroelectricity) 与高介电常数 (dielectric constant)。对苯胺酸进行氘代 (Deuteration) 处理，可使其相变温度 (transition temperature) 升高50 K以上，其中经氘代的氯冉酸 (chloranilic acid) 的相变温度甚至超过了室温。在室温空气环境中，该类晶体呈现出清晰的极化滞回 (polarization hysteresis) 曲线，且矫顽场 (coercive field) 较小。对苯胺酸施加静水压 (hydrostatic pressure) 与卤代取代 (halogen substitution)，均通过结构效应对相变温度产生同向调控作用，而氘代取代的调控方式则截然不同。本次观测到的显著氘代效应无法通过氢键 (hydrogen bond) 的几何形变予以解释，而氢键几何形变曾被认为是传统双阱势 (double-well potential) 氢键型铁电性的潜在作用机制。