Dielectric relaxation mechanism in the incommensurate phase of K2SeO4-type crystals

Abstract The dynamic susceptibility x(w) in the incommensurate phase of K2SeO4-type crystals has been derived from the phenomenological kinetic equations of the Landau-Khalatnikov type using phase soliton model. The critical slowing-down of the polarization fluctuation which has been observed around the incommensurate-commensurate transition temperature T c can be explained as the softening of the phase mode of the discommensuration lattice. In the case of K2SeO4 crystals, the frequency of the soft phase mode is estimated as w1/2° = 0.7(T - Tc)1/2 (cm−1) near T c.

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