A 1:1 adduct of phenazine (Phz) with chloranilic acid (H2ca) and bromanilic acid (H2ba), in which nonpolar neutral molecules are connected by the intermolecular O-H⋯N hydrogen bonds, shows ferroelectric transitions. Neutron diffraction analysis of these materials reveals that there are two inequivalent hydrogen-bonding sites below the ferroelectric transition temperature (253 K for Phz-H2ca and 168 K for Phz-H2ba). This asymmetry was also observed by the maximum entropy method (MEM) analysis of the synchrotron X-ray diffractions. The structure analysis results suggest that the origin of the polarization of the material is the symmetry breaking based on the two inequivalent hydrogen bonds.
ASJC Scopus subject areas
- Colloid and Surface Chemistry