Hard-mode Raman spectroscopy and structural phase transition in the relaxor ferroelectric lead scandium tantalate, Pb(Sc_0.5Ta_0.5)O₃

Abstract

The phase transition in the relaxor ferroelectric lead scandium tantalate, Pb(Sc0.5Ta0.5)O3, is investigated in both ordered and partly disordered (Sc, Ta disorder) modifications through the technique of hard-mode Raman spectroscopy. The vibrational modes for ordered para phase, ordered ferroelectric phase, disordered para phase and disordered ferroelectric phase are assigned to different representations of the respective groups (Fm3m (Z=2), R3m (Z=2), Pm3m (Z=1) and R3m (Z=1)) using the usual group-theoretical methods. The temperature evolution of the strong Raman band at 61cm-1 (hard mode) is investigated from 102 K to 873 K, for both phase transitions, namely ordered para to ordered ferro and disordered para to disordered ferro phases. The temperature variations of integrated intensity, full width at half maximum and square of the frequency of the 61cm-1 band are discussed in the light of phase transition mechanisms involved in relaxor ferroelectrics for both cases.

Influence of electric field on local phase transformations in relaxor ferroelectrics PbSc0.5Ta0.5O3 and Pb0.78Ba0.22Sc0.5Ta0.5O3

“…7,14 It has been shown that T ? can be determined from the abrupt sharpening of the Raman peak near 240 cm À1 originating from off-centered B-site cations (see Fig.…”

Cation arrangement in the complex perovskites and vibrational spectra

“…Raman scattering, considering both possibilities, has been demonstrated on disordered and ordered forms of PST, respectively. 35 In the present paper, we analyze only cubic phases of the complex perovskite compounds. In other words, these are phases in which the oxygen compounds are synthesized at high temperatures.…”

Brillouin scattering studies of acoustic phonon modes and central peak in single-crystal Pb(Sc1/2Ta1/2)OSivasubramanian1, Kojima2 2012Phys. Rev. B

“…[11][12][13] Raman and IR spectroscopic studies of PST showed the increase in intensity and narrowing of the width of the phonon modes with increase in B-site chemical ordering. 14,15 The presence of Pb vacancies also strongly influences the structural and dielectric behavior of PST. It has been found that in disordered PST with Pb vacancies (PST-DV) the spontaneous relaxor-ferroelectric transition is suppressed and the compound shows only relaxor behavior.…”