Structural and optical studies on Dy3+:Tb3+ co-doped zinc leadfluoro-borophosphate glasses for white light applications

Abstract A new series of Dy 3+ :Tb 3+ co-doped zinc leadfluoro-borophosphate glasses were prepared by varying Tb 3+ ions concentration through melt quenching technique. Influence of Tb 3+ ions concentration on the structural and spectroscopic properties of Dy 3+ :Tb 3+ co-doped title glasses were explored through FTIR, Raman, optical absorption, luminescence and decay measurements. The phonon vibrational energy of the chosen glass host is found to be 998 cm −1 through Raman spectrum. Dy 3+ ions act as sensitizer to Tb 3+ ions emission which originates from the 5 D 4 metastable state of Tb 3+ ions through non-radiative energy transfer with a maximum efficiency of 44%. At higher Tb 3+ ions concentration, the 4 F 9/2 metastable state of the Dy 3+ ions can also be mutually sensitized by Tb 3+ ions which inturn increases the lifetime of the 4 F 9/2 state of Dy 3+ ions. Nature of energy transfer in both the cases was investigated through Dexter's energy transfer mechanism and Inokuti-Hirayama (IH) model. These results suggest that dipole-dipole type of interaction is responsible for Dy 3+ to Tb 3+ energy transfer and dipole-quadrupole interaction is responsible for Tb 3+ to Dy 3+ energy transfer. The characteristic emission color of the prepared glasses were examined through CIE 1931 chromaticity coordinates and the corresponding correlated color temperature (CCT) values were estimated which indicates the possible neutral white light emission from the title glasses. All these studies concludes that 0.25 wt% Tb 3+ ions co-doped 0.5 wt% Dy 3+ ions incorporated titled glass is more suitable for neutral white light emitting applications.