Study of optical properties and up-conversion mechanism in Nd3+/Yb3+ ions co-doped SiO2-Al2O3-Na2CO3-SrF2-CaF2 glasses for green light emitting display device applications

Abstract

The oxyfluorosilicate glasses with the composition of (44-x)SiO2 + 5Al2O3 + 17 Na2CO3 + 18SrF2 + 15CaF2 + 0.5Nd2O3 + xYb2O3 (x = 0.1, 0.5, 1.0 and 2.0 mol %) have been prepared by conventional melt quenching technique. The optical absorption, emission and up-conversion spectra were carried out. The strong absorption peak observed at 804 nm corresponding to the transition 4I9/2 → 4F5/2 + 2H9/2. The emission spectra were recorded for Nd3+ singly and Nd3+/Yb3+ co-doped glasses with 808 nm laser diode as an excitation source. For the present investigation, the glass co-doped with 0.5 Nd3+, 0.5 mol% Yb3+ ions have the highest emission intensity. PL up-conversion (UC) emission have been analysed under the excitation of 980 nm laser diode. It is observed that four intense up-conversion emission bands at around 500 nm, 537 nm, 596 nm and 662 nm ascribed to the electronic transitions 4G9/2 → 4I9/2, 4G7/2 + 2K13/2 → 4I9/2, 4G5/2 + 2G7/2 → 4I9/2 and 4G7/2 + 2K13/2 → 4I13/2 respectively. The green emission band at 500 nm (4G9/2 → 4I9/2) has the highest peak intensity for 0.5 mol % Nd3+ and 2.0 mol % Yb3+ ions co-doped glass. For the present work the values for n = 1.76, 1.93 and 2.25 for UC emission at 500, 596, 662 nm respectively. The value n≈2 suggesting that two photons are involved in the UC process of present glass system. The above results suggesting that the prepared glasses co-doped with Nd3+/Yb3+ ions may be used for green light emitting display device applications.