Neutral and warm white light emission in Tb3+/Sm3+ zinc phosphate glasses

Abstract

A spectroscopy analysis of Tb3+ and Tb3+/Sm3+ doped zinc phosphate glasses based on emission spectra and decay time profiles was performed. The Tb3+ singly doped glass shows a green overall emission with x=0.258 and y=0.429 CIE1931 chromaticity coordinates, upon Tb3+ excitation at 318nm. Under co-excitations of Tb3+ and Sm3+ at 344, 361 and 374nm, the Tb3+/Sm3+ co-doped glasses display neutral and warm white overall emissions with CIE1931 chromaticity coordinates in ranges of x=0.407–0.487 and y=0.437–0.485, color temperature in the range of 2447–4024K and quantum yield up to 12.38%, depending on the excitation wavelength and relative amount of Tb3+ and Sm3+. In all cases, it was observed that the Sm3+ emission is enhanced by the addition of Tb3+, which is correlated with a quenching of the Tb3+ emission as consequence of a non-radiative Tb3+→Sm3+ energy transfer process. The non-radiative nature of the energy transfer process was inferred by the shortening of the Tb3+ emission decay time observed in the Tb3+/Sm3+ co-doped zinc phosphate glasses. An analysis of the Tb3+ emission decay time profiles by the Inokuti–Hirayama model suggests that an interaction electric dipole–dipole into the Tb3+–Sm3+ clusters might dominate in the energy transfer process with efficiency and probability of 0.23–0.25 and 96.22–111.35s−1, respectively.