engleski

On the Urbach rule in SbSI ferroelectric crystal

Optical absorption edge of SbSI ferroelectric crystal is studied in a broad temperature range. An Urbach behaviour of the absorption edge is observed in paraelectric (T > Tc) and partly in ferroelectric (130 K < T < Tc) phases, whereas deviations from the Urbach rule are revealed at T < 130 K. The influence of crystal lattice disordering of various types on the Urbach absorption edge parameters is studied. The non-Urbach behaviour of the absorption edge is explained by a presence of dynamic structural disordering due to temperature-dependent phonon-defect interactions.

phase transition; ferroelectric; absorption edge; Urbach rule

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