High spontaneous polarization in PbTiO3–BiMeO3 systems with enhanced tetragonality

Pb Ti O 3 – Bi Me O 3 (Me=Fe, Zn1/2Ti1/2, and Zn3/4W1/4) solid solutions exhibit unusually enhanced tetragonality (c/a). Lattice dynamics and structure of PbTiO3–BiMeO3 with enhanced c/a were investigated by Raman scattering technique and x-ray Rietveld method, respectively. The A1(1TO) soft mode, associated with the order parameter spontaneous polarization (PS), abnormally shifts upward, which is different with almost all other PbTiO3-based compounds. It is interesting to find that the A1(1TO) mode increases linearly with the PS displacement. The PS could be basically judged from the variation of A1(1TO) not only with normally reduced c/a but also with unusually enhanced c/a in the PbTiO3-based systems.