Dielectric dispersion of ferroelectric triglycine sulphate in the microwave region

The dispersion of the dielectric constant of triglycine sulphate (TGS) is investigated in detail by measurements up to 10 GHz. The dispersion can be well described by a Debye equation. The characteristic relaxation frequency f̃o=fσ (σs-σ∞) shows only in the ferroelectric region an evident temperature dependence. The experimental data are compared with a recent phenomenological theory for the ferroelectric dispersion of electrostrictive ferroelectrics with a transition of second order; qualitative agreement is stated. The ratio of Curie-constants in the para-and ferroelectric region Cp/Cf is calculated for a clamped adiabatic crystal and compared with the experiment.