Doping effect on the phase transition temperature in ferroelectric SrBi sub(2-x)Nd sub(x)Nb sub(2)O sub(9) layer-structured ceramics: a micro-Raman scattering study

The temperature dependence of Raman spectra for SrBi sub(2-x)Nd sub(x)Nb sub(2)O sub(9) ceramics (x from 0 to 0.2) has been studied in a wide temperature range from 80 to 873K. It is found that the peak position of the A sub(1g)[Nb] phonon mode at 207cm super(-1), which is directly associated with the distortion of NbO sub(6) octahedron, decreases with increasing Nd composition, while the A sub(1g)[O] phonon mode at 835cm super(-1) increases. Moreover, both the peak position and intensity of the A sub(1g)[Nb] phonon mode reveal strong anomalies around the ferroelectric to paraelectric phase transition temperature. It indicates that the phase transition temperature decreases from about 710 to 550K with increasing Nd composition, which is due to the fact that the introduction of Nd ions in the Bi sub(2)O sub(2) layers reduces the distortion extent of NbO sub(6) octahedron. Copyright copyright 2011 John Wiley & Sons, Ltd. The temperature dependence of Raman spectra for SrBi sub(2-x)Nd sub(x)Nb sub(2)O sub(9) ceramics has been measured. Many anomalous changes were observed and discussed in detail. The T sub(C) decreases from ~710 to 550 K with the Nd composition because of the reduced distortion extent and tilting angle of NbO sub(6) octahedron.