Raman spectroscopic study of molten PbBr2-NaBr and PbBr2-KBr mixtures

Raman spectra of molten PbBr2-NaBr and PbBr2-KBr systems showed the strongly polarized bands at about 150 cm−1. These Raman bands were identified as the totally symmetric stretching vibration modes of tetrahedral species PbBr42− by consulting with the result of neutron diffraction. The shape of Raman spectra did not change drastically with increasing concentration of alkali bromide or a rise of temperature. These results suggest that there existed PbBr42− complex ions in the mixture melts, which might not form further clustering or networking.