Dielectric and Raman studies of La modified Lead Scandium Niobate ceramics

The disordered Lead Scandium Niobate (PSN) is a typical relaxor having high dielectric constant and dielectric maximum temperature (Tm) above room temperature. La modified samples showed shift in dielectric maxima temperature towards lower temperature side, broadening of their phase transition, and the frequency dispersion in their permittivity. However, these samples exhibit relaxor feature for up to 10% substitution but for higher values these are very diffuse in nature. Raman spectra showed a shift to lower frequencies of F2g mode and changes in the intensities and the linewidths of the dirty modes on increase in the La subtitution. The low-wave number (180 to 400 cm-1) regions showed significant change due to structural distortion with increase in the La substitution.