Wide Band Dielectric Spectroscopy at Ferroelectric Phase Transition of BaTiO3 Ceramics

Abstract

Ultrawide band dielectric spectra from kHz to THz were measured to investigate quantitatively the contributions of ionic and dipole polarizations to the ferroelectric phase transition in BaTiO3 (BT) ceramics. Permittivity derived from ionic polarization (εionic) exhibited its maximum at the Curie temperature (Tc), attributing to the softening of the soft phonon mode. Permittivity derived from dipole polarization (εdipole) was nearly constant below the Tc, while εdipole remained above the Tc and εdipole increased on cooling, exhibiting its maximum near the Tc. The behavior in εdipole above the Tc could be interpreted as precursor phenomenon of ferroelectric phase transition and the εdipole above the Tc was due to the local tetragonal type distortion in paraelectric phase.