▎ 摘　　要

The effect of graphene flakes (GF) admixing to the Er3+,Yb3+:Y2O3 nanocrystalline powders on upconversion (UC) emission was investigated. It was found that GFs significantly reduce not only the overall intensity of UC transitions but also change their intensity distribution. In particular the red band corresponding to the F-2(9/2) -> I-4(15/2) transition decreases in comparison to the green band associated with the H-2(11/2) -> I-4(15/2) and S-4(3/2) -> I-4(15/2) transitions which were significantly weakened. The green to red ratio of transition band intensities (G/R) varied with a content of graphene flakes. It was observed that G/R ratio was dependent on excitation laser power. For larger concentration of GFs there was observed the broadband white emission centered at 650 nm that increased exponentially with excitation power with simultaneous dumping of UC transitions.