Structural and Raman spectroscopic studies of poled lead-free piezoelectric sodium bismuth titanate ceramics

Lead-free piezoelectric sodium bismuth titanate (NBT) ceramics are synthesized by a solid state reaction method. Poled NBT ceramics possess rhombohedral R3c structure. Vibrational phonon frequencies associated to Bi-O, Na-O, TiO6 octahedra and oxygen vibrations are observed. Experimentally unreported lowest frequency region peak centered at 111 cm−1 is assigned to E(TO1) mode related to Bi-O vibrations. Appearance of lowest frequency mode may be due to well-polished surfaces with reduced Rayleigh scattering background and well-defined ordering of Bi and Na ions in the lattice.