Dipolar ordering and relaxations in acetonitrile-β-hydroquinone clathrate

Single crystals of this clathrate have been studied by measurements of the frequency and temperature dependent dielectric permittivity as well as with polarization-electric field cycles and x-ray diffraction. The dipole moments of the acetonitrile guest molecules form Ising chains that are coupled by the electric dipole-dipole interaction and that are arranged in a triangular array. At 345 K a phase transition from a partially disordered antiferroelectric to a ferrielectric arrangement is observed.