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Dielectric dispersion in ferroelectric hydrogen bonded glicyne phosphite crystal was investigated in the frequency range 100 Hz -27 GHz. Dielectric relaxation of Debye type observed in the paraelectric phase shows a critical slowing down of the polarization fluctuations. The relaxation frequency decreases with temperature according to fs = 0.305(Τ -Τ0) GHz in the paraelectric phase. The activation energy for flipping dipole motion ΔU = 2.07kΤc confirms order-disorder character of the phase transition. In the ferroelectric phase pronounced low frequency (100 Hz -1 MHz) dispersion related to domain contribution to permittivity was found.

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The dielectric behaviour of ferroelectric hydrogen‐bonded betaine phosphite crystals is investigated in the frequency range up to 77 GHz. The dielectric dynamics of Debye‐type shows a critical slowing‐down of the polarization fluctuations. The frequency of the relaxational soft mode in the paraelectric phase varies according to vs = 0.36(T‐218) GHz and decreases to 2.4 GHz at Tc = 224 K. The calulated activation energy for flipping proton motion ΔU = 2.7kTc shows the order‐disorder character of the proper ferroelectric phase transition.