Raman studies in tetragonal structure PbTeO3

Raman spectra of tetragonal phase PbTeO3 have been acquired from single-crystal sample synthesized by hydrothermal method. Theory calculations have been carried out to analyze the Raman spectra. Raman bands between 600 cm−1 and 800 cm−1 are attributed to the internal modes of Te-O bonds in TeO3 pyramid, while Raman bands between 136 cm−1 and 400 cm−1 are assigned to the external modes of TeO3 pyramid. The vibration corresponding to Raman frequencies below 119 cm−1 are consisted of Pb lattice modes and external modes of TeO3. The effects of pressure on the Raman spectrum of PbTeO3 have been investigated up to 23 GPa. A splitting of 119 cm−1 peak was observed at 13.4 GPa, which may caused by the rotation of TeO3 pyramid instead of the phase transition.