Temperature-dependent Raman spectra of ferroelectric potassium strontium niobate

The temperature dependence of vibrational modes polarized parallel to the polar axis of potassium strontium niobate, a 'tungsten-bronze'-type ferroelectric, is investigated using polarized Raman techniques. The low-frequency Rayleigh component of the spectrum may be fitted to a Debye relaxation spectral function, the relaxation time appearing to increase towards the ferroelectric-paraelectric phase transition as is observed in some hydrogen-bonded ferroelectrics. Dielectric dispersion measurements are presented which are consistent with a Debye relaxation over a comparable frequency regime. Measurements of the integrated intensity of the A 1 (TO) modes as a function of temperature are discussed in terms of the static dielectric properties of the material.