Transformation of the relaxational soft mode into an optical phonon in rochelle salt

Abstract

The dielectric spectra ε′(ν) and ″(ν) of the Rochelle salt have been measured at frequencies 4–24 cm⁻¹ and temperatures 300–80 K. The low-frequency dielectric relaxation known as a ferroelectric soft mode has been observed to transform into an optical phonon at low temperatures, far from the phase transition point T₁=255 K.