Blue-green photoluminescence in BaZrO3−δ powders

BaZrO3−δ (δ = 0.0, 0.1 and 0.2) powders were prepared by the sol–gel process. XRD patterns revealed that all samples present a major cubic structure as well as a ZrO2 secondary phase for δ = 0.1 and 0.2 samples, which is confirmed by the Raman study. Besides, blue-green photoluminescence (PL) emission at room temperature was observed. This emission is directly related to the decrease of singly ionized VO and the increase of the doubly ionized VO clusters, leading to the formation of intermediary energy levels in the band gap where an electron and a hole can recombine in the structure.