Broadband yellow–white and near infrared luminescence from Bi-doped Ba10(PO4)6Cl2 prepared in reductive atmosphere

Bismuth ions doped Ba10(PO4)6Cl2 was synthesized by solid state reaction and its spectral properties were investigated. The results showed that the samples prepared in air only presented typical ultraviolet (UV) luminescence of Bi3+ at 370 nm, however broadband yellow–white and near infrared (NIR) emission could be observed in the samples prepared in reductive atmosphere, indicating those broadband emissions are related to the presence of low valent bismuth species. Correlating excitation and emission data with the charge of available lattice sites suggest that Bi3+ coexist with Bi+, and each locate on one of the two available Ba2+ lattice sites. We propose that broadband yellow–white and NIR emissions are ascribed to the related transitions of Bi+ ion.