Color-tunable emission by cation substitution in Ba3−ySryY4O9:Bi3+ and sites occupation preference

Highlights: • when Sr²⁺ ions are doped into samples, the abnormal two-peak emission behavior can be achieved under 347 nm excitation. • The present work studies sites occupation of Bi³⁺ by employing the complex crystal valance bond theory calculation. • Analysis suggests that two components of emission band are ascribed to Bi³⁺ which occupies Y2/Y4 and Ba1/Ba2 sites. - Abstract: A series of Ba₃Y₄O₉:Bi³⁺ phosphors with trigonal lattice in the R3 (146) space group are investigated in the aspect of structure and luminescence. The Ba₃Y₄O₉:Bi³⁺ phosphor exhibits a promising broad yellowish-green emission peaking at 524 nm at the excitation of 347 nm. When Sr²⁺ ions are introduced into series of samples, the abnormal two-peak emission behavior centered at 412 nm and 524 nm can be observed, simultaneously. Eventually, tunable emission colors are obtained from yellowish-green to blue via controlling the ratio of Sr²⁺/Ba²⁺ content. Through calculation, the corresponding environmental factor of every Y³⁺ and Ba²⁺ site can be obtained. Analysis suggests that two components of the excitation band at 344 and 361 nm are ascribed to Bi³⁺ ions which occupies Y(2)/Y(4) and Ba(1)/Ba(2), respectively. It can be further expected that the anomalous emission of 412 nm is attributed to Bi³⁺ ions which occupies Sr(1)/Sr(2) sites when substitution occurs.