Colorless Bi₂O₃-containing borophosphate glasses with high refractivity

Abstract

The effects of P₂O₅ substitution on the coordination structure of a Bi³⁺ in Bi₂O₃–B₂O₃ glasses were examined by applying ¹¹B and ³¹P MAS-NMR spectroscopy. Observation of the wide optical bandgap after the substitution revealed a substantial difference in the solvation shell structure between the P₂O₅ substituted and the P₂O₅-free Bi₂O₃-containing glasses, i.e., the P₂O₅ substitution replaced by the B₂O₃ is effective for forming the solvation shell, which leads to weak ligand field around a Bi³⁺. We report the optical properties of the Bi₂O₃–P₂O₅–B₂O₃ glass providing a wide optical bandgap (∼3.6 eV) and high refractive index (∼2.0).