Preparation and characterization of upconversion luminescent Tm3+/Yb3+ co-doped Y2O3 nanophosphor

Tm³⁺/Yb³⁺ co-doped Y₂O₃ nanophosphor has been synthesized by the solution combustion technique. Heat treatment of the phosphor materials at higher temperatures modifies the structural and optical properties. At low concentration of Yb³⁺, an intense upconversion emission is observed in blue region (478?nm) on excitation with 976?nm radiations. Emission has also been observed in the ultraviolet (UV) region viz. at 300?nm. The intensity of blue emission initially increases with dopant concentration as well as with the annealing temperature. However, for higher concentrations of Yb³⁺ (10?mol%), emission in the blue region is greatly suppressed and NIR emission at 813?nm appears with a large intensity. Intensity ratio of NIR and blue emission (I _NIR/I _B) reaches 74, resulting in almost monochromatic light at 813?nm. To check the suitability of blue emission for display devices, CIE color coordinates (x,y), color purity and the dominant wavelength (?? _d) for the blue emission have been calculated and the resulting value is found to be close to the coordinates of available standard blue phosphors.