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

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 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 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 (4S3/2 level) has been found to be ∼446 μs.