Phenomenological model for the antiferroelectric phase transition in thin films and small particles

A phenomenological Landau model for the antiferroelectric phase transition in thin films and small cylindrical and spherical particles is developed. The boundary value problem was solved numerically for polarizations of polar sublattices and components of the susceptibility tensor. The spatial distribution of polarization and susceptibility and their temperature dependences were calculated. The enhancement of diagonal components of the susceptibility tensor compared to bulk was found. The size-dependent shift of the antiferroelectric phase transition temperature was obtained.