Vibrational Dynamics of Ferroelectric K(Ta1-xNbx)O3 Studied by Inelastic Light Scattering.

The Fano resonance of non-doped KTa1-xNbxO3 (x = 0.32) single crystals was investigated by the Raman spectroscopy. The intensity of central peak (CP) and parameters of the Fano resonance revealed a significant anomaly in the vicinity of the Curie temperature, TC = 259 K. The vibrational dynamics and the symmetry breaking in the cubic phase are discussed in the framework of weak random fields. It is concluded that the coupling between continuum states induced by polar nanoregions (PNRs) and a transverse optic (TO2) phonon at about 194 cm−1 is the origin of a Fano resonance in non-doped KTN crystals. [ABSTRACT FROM AUTHOR]