Low temperature Raman scattering study of barium doped lead ytterbium tantalate ceramics

Abstract

Raman spectra of a complex perovskite system (Pb[Formula: see text]Ba[Formula: see text](Yb[Formula: see text]Ta[Formula: see text])O3, [Formula: see text] and 0.2 have been studied at low temperature in the range of 10–250[Formula: see text]K. The fascination of the system is that it undergoes a crossover from a highly ordered antiferroelectric ([Formula: see text]) to ferroelectric ([Formula: see text]) to disordered relaxor ferroelectric ([Formula: see text]). The nature of splitting that prevails in F2g ([Formula: see text][Formula: see text]cm[Formula: see text]), F1g ([Formula: see text][Formula: see text]cm[Formula: see text]) modes and their gradual merging and disappearance with [Formula: see text] indicates an orthorhombic symmetry for [Formula: see text] and a pseudo-cubic structure for [Formula: see text]. The mode at 420[Formula: see text]cm[Formula: see text] suggests the existence of rhombohedral distortion in all the compositions. The soft mode behavior of the F2g modes has been analyzed by fitting the data with the power law [Formula: see text].