Effects of rare earth substitution on the optical properties of Bi2MoO6 for coloring applications

• New class of colored compounds BiREMoO6 (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.

A new class of colored inorganic compounds, BiREMoO6 (RE = Pr, Nd, Sm, Tb and Yb) has been synthesized by a solid state route. The substitution of different rare earths for Bi3+ in Bi2MoO6 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 O2p valence band to conduction band made of primary Mo4d and secondary Bi6p. The substitution of RE3+ 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 Bi2MoO6 from 2.99 eV to 2.19 eV. The developed compounds exhibited different shades of yellow hue and demonstrated good coloration to plastics.

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