Vibrational properties of impurity substituted α′-NaV2O5

Abstract We report the polarized infrared reflectance of Ti 4+ -doped α′-NaV 2 O 5 and an analysis of the frequency dependent conductivity. Impurity incorporation allows us to resolve a number of new rung-polarized vibrational features due to local symmetry breaking. Variable temperature measurements both above and below the charge ordering transition indicate that the majority of zone-folding modes in Ti 4+ substituted α′-NaV 2 O 5 are a subset of those in the pristine material; minute new folded modes are observed at 46 ( E ∥ a ), 105 ( E ∥ a ), and 636 ( E ∥ b ) cm −1 . We discuss our results in terms of disruption of the rung in the vicinity of the Ti 4+ defect.