Investigations of the free-domain-wall contribution to the dielectric properties of TGS crystals using a fast-response step voltage technique

Single-crystal samples of triglycine sulphate in the form of capacitors with electrodes applied perpendicular to the ferroelectric axis were studied using an electrical charge/discharge method to investigate their dielectric properties. Experiments at room temperature on freshly prepared capacitors yielded well defined relaxation times with corresponding relaxation frequencies, f r , in the audio-frequency range. The relaxation frequencies were found to change with temperature below the Curie temperature according to the equation f r =f r0 exp(- Delta u/kT) and the average value of the activation energy, Delta u, was found to be 0.509+or-0.013 eV. The magnitude of the currents, and the total charge associated with each charge and corresponding discharge decreased in a pronounced manner as the samples aged. Samples with only a few domains showed much smaller current and charge than those having more domains. Consequently, the polarisation process could be attributed to the dynamics of the free domain walls.