Energy transfer and photoluminescence properties of Dy3+/Tb3+ co-doped oxyfluorosilicate glass–ceramics for solid-state white lighting

Singly doped Dy3+, Tb3+ and co-doped Dy3+/Tb3+ ions in oxyfluorosilicate glass–ceramics were prepared by conventional melt quenching technique to study their luminescence properties for the development of white light emitting diodes. The X-ray diffraction measurements confirmed the amorphous and KNbO3 crystalline nature of precursor glass and glass–ceramics, respectively. The effect of increasing the concentration of Tb3+ ions on the green emission from the 5D4 excited level has been investigated. The decay profiles of 4F9/2 excited level of Dy3+ ion were fitted to double exponential function and Inokuti-Hirayama (IH) model to determine the energy transfer rates from Dy3+ to Tb3+ ions. All the chromaticity (x, y) color co-ordinates determined from the emission spectra were found to be within the white light region of the CIE chromaticity color diagram.