Effects of rare earth substitution on the optical properties of Bi{sub 2}MoO{sub 6} for coloring applications

Highlights: • New class of colored compounds BiREMoO{sub 6} (RE = Pr, Nd, Sm, Tb, Yb) was synthesized. • The substitution of RE gently red shifts the absorption edge to low energy side. • The differences in band gap depend on the position of the RE f bands. • The yellow colored compounds demonstrated good coloration to plastics. - Abstract: A new class of colored inorganic compounds, BiREMoO{sub 6} (RE = Pr, Nd, Sm, Tb and Yb) has been synthesized by a solid state route. The substitution of different rare earths for Bi{sup 3+} in Bi{sub 2}MoO{sub 6} produces visible light responsive compounds by gently red shifting the absorption edge to low energy side. The visible light absorption is based on the charge transfer transitions from O{sub 2p} valence band to conduction band made of primary Mo{sub 4d} and secondary Bi{sub 6p}. The substitution of RE{sup 3+} introduces partially occupied 4f electronic levels in between the band gap and the position of 4f level depend on the number of f electrons which allows tuning the band gap. Thus the rare earth substitution provides an opportunity to tailor the band gap of Bi{sub 2}MoO{sub 6} from 2.99 eV to 2.19 eV.more » The developed compounds exhibited different shades of yellow hue and demonstrated good coloration to plastics.« less