Synthesis and luminescent properties of Y₂O₃:Er³⁺ nanometer powder coated with SiO₂

The Y₂O₃:Er³⁺ nanometer phosphors coated with SiO₂ was synthesized by the microemulsion method. The X-ray diffraction results showed that the as-prepared powders were cubic phase of Y₂O₃. The TEM pictures demonstrated that the powders have the nearly spherical and the average diameter of the particles was in the range of 60~80 nm. Under the excitation of 980 nm diode laser, a very strong green emission centered at 562 nm and a red emission centered at 660 nm were observed, which were assigned to the transitions of ⁴S_3/2/² H_11/2→⁴I_15/2 and ⁴F_9/2→⁴I_15/2 energy levels of Er³⁺ ions, respectively. The research on luminescent intensity and the exciting power relations revealed that this up-conversion process was a two-photons absorption process. Because Y₂O₃ (nucleus)/SiO₂ (shell) has highly effective performance on the up-conversion luminescence and was easy to dissolve in the water and united with organic matter and biological member, the application of this nanometer nuclear-shell structure material in the biological fluorescence mark domain is significance.