Structural and up-conversion properties of Er3+ and Yb3+ co-doped Y2Ti2O7 phosphors

Abstract

Y₂Ti₂O₇ (YTO) and Er³⁺/Yb³⁺ co-doped Y₂Ti₂O₇ (EYYTO) phosphors have been prepared by solid-state reaction method. Structures of YTO and EYYTO phosphors are identified as face centered cubic pyrochlores. Up-conversion emission spectra of EYYTO under 976 nm excitation is studied, which revealed three prominent emission lines at ∼524, 548 and 661 nm originating from ²H_11/2 → ⁴I_15/2, ⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 electronic transitions of Er³⁺ ion, respectively in green and red regions. The power dependence study suggests that these bands arise due to two photon absorption. The monodispersed laser ablated colloidal solution of EYYTO shows strong red and green emissions on excitation with 976 nm laser. The variation of luminescence intensity at different laser excitation powers is observed and thus a color can be tuned. The photoluminescence lifetime of green band at 548 nm (⁴S_3/2 level) has been found to be ∼446 μs.