Polarizability investigation by first order phase transition in the self-consistent phonon approximation for PSN system

Abstract

Considering a quadratic Anharmonic model Hamiltonian and using double time temperature dependent Green's function method and Dyson's equation treatment, expression for polarizablity in the frequency response for mixed perovskite type ferroelectrics has been obtained. Using the experimentally observed temperature dependent dielectric constant, loss tangent, soft mode frequency and width for Na_1-x K_xNbO₃ (where x = 0, 0.4 and 0.5), the polarizablity has been calculated for these samples at 10 and 100 kHz.