Influence of yttrium ions on the emission transfer features of Ce3+/Yb3+ co-doped lithium silicate glasses

Optical absorption absorption and photoluminescence spectra (PL) of the glasses possessing compositions (49 - x) Li2O-x Y2O3-50 SiO2:1.0 Ce2O3/1.0Yb(2)O(3) and (49 - x) Li2O-x Y2O3-50 SiO2:(0.5 Ce2O3 + 0.5 Yb2O3) with x varying from 5 to 15 mol% were studied. The PL spectra of Ce3+ doped glasses excited at 360 nm exhibited two broad parity allowed 5d(D-2) -> 4f(F-2(5/2),(7/2)) bands in the blue spectral region, whereas the spectra of Yb3+ doped glasses excited at 900 nm exhibited a broad emission band centered at about 980 nm due to F-2(5/2) -> F-2(7/2) transition. A significant enhancement in the intensity of NIR emission is observed due to the sensitization with Ce3+ ions. The increase in the rate of energy transfer from Ce3+ to Yb3+ could be observed with increasing Y2O3 content. The reasons for such improvement have been discussed within a framework of structural modifications taking place in the vicinity of Yb3+ ions. (C) 2012 Elsevier B.V. All rights reserved.