Short-Range Ferroelectric Order Induced by Proton Transfer-Mediated Ionicity

Short-range ferroelectric order is postulated to explain unusual one-dimensional dielectric response in ferroelectric 1,4-diazabicyclo[2.2.2]octane. In this pure organic salt, the polar regions are created in the antiferroelectric matrix of hydrogen-bonded polycationic chains due to the random proton transfers in NH + ···N hydrogen bonds. This results in a local spontaneous polarization along the nonferroelectric direction of the crystal, inconsistently with its macroscopic symmetry. The phenomenon arising from a self-discrimination of the crystal ionic structure strongly resembles the behavior of ferroelectric relaxors induced by an artificial compositional disorder.