Dielectric dispersion as an indication of the formation of a polar phase in ferroelectrics

The regularity of the appearance of dispersion in the rf range immediately at the Curie point upon transition to the polar phase is demonstrated using the three-dimensional dependences of the permittivity ε22′ (f, T) for a triglycine sulfate single crystal as an example. This regularity is common to all ferroelectrics and can be used for the direct objective determination of the phase transition temperature.