Formation and rapid evolution of domain structure at phase transitions in slightly inhomogeneous ferroelectrics and ferroelastics

Authors:
  • ABA. M. Bratkovsky
    A. M. Bratkovsky
  • ALA. P. Levanyuk
    A. P. Levanyuk
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Abstract
We present the analytical study of stability loss and evolution of domain structure in inhomogeneous ferroelectric and ferroelastic samples for exactly solvable models. The model assumes a short-circuited ferroelectric capacitor (free ferroelastic) with two regions with slightly different critical temperatures Tc1 > Tc2, where Tc1-Tc2 << Tc1, Tc2. We show that even a tiny inhomogeneity like 10-5 K results in splitting the system into domains below the phase transition temperature. At T < Tc2 the domain width a is proportional to (Tc1-T)/(Tc1-Tc2) and quickly increases with lowering temperature. The minute inhomogeneities in Tc may result from structural (growth) inhomogeneities, which are always present in real samples, and a similar role can be played by inevitable temperature gradients.