Piezoelectric Response of Plastic Ionic Molecular Crystals: Role of Molecular Rotation

Plastic ionic molecular crystals are a novel class of materials that have attracted recent interest due to the discovery ferroelectric and piezoelectric properties together with an orientationally disordered mesophase high plasticity. Despite growing interest, little is known about mechanisms underpin their properties. To address this knowledge gap, we use density functional theory calculations van der Waals functionals study dielectric, piezoelectric, elastic 11 plastic crystals. The coefficients were found reach values comparable inorganic piezoelectrics. Further, some strikingly large anisotropies. For HQReO4 (quinuclidinium perrhenate) anisotropy |d16/d33| = 118 was found, times LiNbO3, phase pure noted for its anisotropy. Our links rotational motion constituent molecules in response shear stress. coefficients, yet modest dielectric permittivity, results coupling coefficients─a measure suitability energy harvesting─with up 0.79. points engineering as key realizing outstanding these compounds.