Optical response and luminescence characteristics of Sm3+ and Tb3+/sm3+ co-doped potassium-fluoro-phosphate glasses for reddish-orange lighting applications

Potassium-fluoro-phosphate (KFP) glasses singly doped with different concentrations of samarium (0.1, 0.3, 0.5, 1.0, 1.5 and 2.0 mol%) and co-doped with Tb3+(0.1, 0.5, 1.0 mol%) were prepared, and their luminescence properties were investigated. Optical transition properties of Sm3+ ions were evaluated by using Judd-Ofelt theory. Various emission properties were studied from luminescence spectra. Reddish-orange emission of Sm3+ exhibits mainly by 4G5/2 level to 6H7/2 located at 600 nm. Concentration quenching and energy transfer were observed from fluorescence spectra and decay curves respectively. The non-exponential decay profiles were analyzed Inokuti-Hirayama model (I-H). From this model, various energy transfer kinetic parameters were also calculated and analyzed. By co-doping with Tb3+, energy transfer from Tb3+ to Sm3+ takes place and contributes to enhancement in emission intensity and intense reddish-orange emission was obtained. The optimized properties of the Tb3+/Sm3+ co-doped KFP glasses indicate that these glasses can be used as luminescent materials.