Dipolar ordering and glassy freezing in a clathrate

The dielectric permittivity of methanol-β-quinol clathrates has been studied as a function of temperature, frequency and methanol concentration. Higher concentrated samples undergo a first-order antiferroelectric transition, lower concentrated ones are established as dipole glasses. The main structural motif are ferroelectric chains, respectively chain segments. The largely different strength of the intrachain and the interchain coupling, the frustration leading to the glass state, and the relaxational dynamics are interpreted in terms of the dipole-dipole interaction in combination with the rhombohedral symmetry of the host lattice.