Raman scattering study of ß-Sr(0.33)V(2)O(5) in charge disordered and ordered phase.

Polarized Raman spectra of the strontium vanadium oxide bronze ß-Sr(0.33)V(2)O(5) are measured in the temperature range between 300 and 77 K. The charge ordering phase transition at about 165 K is characterized by the appearance of new Raman-active modes in the spectra, as well as through an abrupt change of the phonon frequencies and dampings. The Raman scattering spectra of ß-Sr(0.33)V(2)O(5) in the charge disordered phase are in apparent resemblance with those of α'-NaV(2)O(5), which suggests that there is a similar charge-phonon dynamics in both compounds. We also suggest that the electrons are delocalized into V(1)-O(5)-V(3) orbitals in the mixed valence state of ß-Sr(0.33)V(2)O(5).