Micro-Raman spectroscopic investigation of rare earth-modified lead zirconate titanate ceramics

Rare earth-modified lead zirconate titanate (PRZT) ceramics [R/Zr/Ti = 8/60/40; R = La and Pr] are prepared by a sol–gel technique. Substantial changes in the dielectric, ferroelectric and piezoelectric properties are observed between La- and Pr-modified PZT ceramics. To correlate the observed differences in the electrical properties with structural modifications, temperature-dependent Raman scattering measurements have been carried out. Significant asymmetric phonon line broadening with a noticeable downward shift has been observed for peaks associated with E and A1 symmetry, particularly in Pr-modified PZT when the sample temperature increases. In addition, low-temperature Raman spectra of Pr-modified PZT show splitting of the A1(1TO) mode and appearance of the sub-peak structures. Such sub-peak structures arising around A1(1TO) mode could be due to the presence of thermodynamically stable defect-impurity complexes.