EXAFS study of Er,Yb doped hollow and dense SiO2 microspheres

PL measurements of the Er3 + emission at 1.54 μm were performed, on hollow and dense SiO2 microspheres, for different Er3 +/Yb3 + ratios, ranging from 1:3 to 1:10 mol%. Upconversion was observed in all samples, ordered by efficiency for the studied Er,Yb environments as: glass-ceramic (NaYF4 environment) ≫ hollow SiO2 microspheres (Er,Yb fluoride crystalline environment) > dense SiO2 microspheres (Er,Yb oxide crystalline environment). X-ray excited optical luminescence (XEOL) confirmed the Er green upconversion results.