Phase transition study on degenerate modes of Pb(Yb1/2Nb1/2)O-3 and Pb(Yb1/2Ta1/2)O-3

Abstract

Pb(Yb1/2Nb1/2)O-3 [PYN] and Pb(Yb1/2Ta1/2)O-3 [PYT] are highly ordered enough to be a prototype for spectroscopic studies of complex lead-based perovskite compounds Pb(B', B")O-3 system. We find out changes in the numbers of vibrational mode at each phase by Raman scattering. PYN based antiferroelectrics have the modes with the triple degeneracy. It may originate from antiparallel arrangements of cations and the accompanied octahedral tilting. PYT systems display an additional degeneracy as lowering a temperature. These results implicate Raman spectroscopy is more efficient than other methods for characterizing phases of PYN and PYT.