Ferroelectric phase transitions and domain relaxation in KTa1-xNbxO3

Abstract
Linear birefringence, dielectric permittivity and second harmonic generation are measured on KTa1-xNbx with x = 0.03 in order to elucidate its sequence of para-to-ferroelectric phase transitions, which occur at about 44, 42 and 39 K. The data are compatible with cubic-tetragonal-orthorhombicrhombohedral symmetry changes as in KNbO3. Domain formation and relaxation gives rise to slow polydispersive polar dynamics as evidenced by dielectric dispersion and time-dependent SHG intensity.