Upconversion Luminescence Properties of Gd₂O₃: Er³⁺ Nanospheres and Gd₂O₃: Er³⁺@Silica Nanocomposites

Abstract

The upconversion luminescence (UCL) of Gd 2 O 3 : Er 3+ monodisperse nanospheres, synthesized by multistep chemical method, and nanoparticles, produced by combustion synthesis, are presented for comparison. The UCL of nanospheres Gd 2 O 3 : Er 3+ and Gd 2 O 3 : Er 3+ @Silica have shown strong red or green emission under excitation at 976 nm or 980 nm by a diode laser with a remarkable increase of the bright red color in the nanospheres. In the core/shell structured nanospheres Gd 2 O 3 : Er 3+ @Silica, we find a higher intensity of upcoversion emission, increased stability and better dispersion capability in solvents and water. The UCL intensities of green and red color while 976 nm or 980 nm excitation were dependent on the diode laser power. The slope values of Er 3+ ion's transitions 2 H 11/2 4 I 15/2 , 4 S 3/2 4 I 15/2 and 4 F 9/2 4 I 15/2 in the silica-coated nanospheres are 1.99, 1.62 and 1.66 respectively, which properly indicate the two-photon mechanism of upconversion emission. The synthesized Gd 2 O 3 nanospheres codoped with Yb and Er show strong UCL intensity than those of Gd 2 O 3 : Er 3+ . The obtained Gd 2 O 3 : Er 3+ nanospheres and nanoparticles, as well as Gd 2 O 3 : Yb 3+ , Er 3+ and its silica-coated versions, are promising materials to develop with potential application in high technology and biomedicine.

Recent Progress in Nanostructured Functional Materials and Their Applications II

“…In the second paper, 188) Eu 3+ doped La 3 PO 7 nanoparticles are synthesized by combustion method and their optical properties are investigated in detail. The third paper 189) shows the results of upconversion luminescence properties of Ge 2 O 3 nanoparticles doped with Er 3+ and that combined with silica nanocomposite. In the fourth paper, 190) characterization of Gd 2 O 3 :Eu 3+ nanocomplexes conjugate with IgG for the identification of CEA tumor cells.…”