Raman and IR phonons in ferroelectric Sr 0.35 Ba 0.69 Nb 2 O 6.04 single crystals

IR and Raman spectra of strontium barium niobate (SBN) with 35% of Sr were measured in a broad interval of temperatures (20–800 K). Anomalies in the frequencies and intensities of some IR and Raman active phonons were observed. These modes are presumably related to Sr and Nb–O vibrations. This brings evidence that, apart from the order–disorder nature of the ferroelectric phase transition in SBN, there could be some ferroelectricity induced by cation displacements in the low Sr content samples.