Effects from A-site substitution on morphotropic phase boundary and phonon modes of (Pb1–1.5xLax)(Zr0.42Sn0.40Ti0.18)O3 ceramics by temperature dependent Raman spectroscopy

The complex perovskite ferroelectric/antiferroelectric of (Pb 1−1.5 x La x )(Zr0.42Sn0.40Ti0.18)O3 (PLZST) ceramics have been investigated by Raman scattering spectra from 77 to 480 K. It was found that phase transition occurs between La composition of 2.6% and 2.8% for PLZST ceramics. Softing of A1(TO1) mode and dramatic changes of relative strength from E(TO2) mode are observed at morphotropic phase boundary (MPB). Moreover, it was found that MPB characteristic shows a wider and lower trend of temperature region with increasing La composition. This could be ascribed to the diminishment of the energy barrier and increment of A-cation entropy.