Raman scattering study of the soft phonon modes in the ferroelectric srtio3

Abstract

Raman scattering spectra from soft phonon branches in SrTiO3 were observed for the case that the ferroelectric transition was actuated by either applying the (100> uniaxial mechanical stress or adding small amounts of Ba ion. Variations of phonon frequencies of the ferroelectric soft mode were examined. It was found that the soft mode frequencies do not tend toward zero value as the stress or the temperature approaches toward the critical point, though the observed Raman line profile remains always underdamped.