Green and red luminescence in Tb³⁺ and Eu³⁺:Zn₂SiO₄ powders

We report the preparation and photoluminescence spectral analysis of Tb³⁺ and Eu³⁺ doped Zn₂SiO₄ powders in sol-gel sol-gel process. On exposure to an UV source, these rare earth ions doped zinc silicate materials have shown prominent luminescent green and red colors, due to the electronic transitions of ⁵D₄→⁷F₅ (Tb³⁺) and ⁵D₀→⁷F₂ (Eu³⁺) respectively. The green emitting transition of Tb³⁺ material has been a magnetic dipole in nature and the red emitting transition of Eu³⁺ material has been due to an electric dipole in nature with a hypersensivity in its luminescence. Systematic characterization has been carried out to understand the fluorescence efficiency of these two materials by measuring their excitation, photoluminescence, time-resolved luminescence spectra and lifetimes of the emission transitions (⁵D₀→⁷F_0,1,2,3,4&5) of Eu³⁺ at two different excitation wavelengths of 226 nm and 395 nm. However, for the emission transitions (⁵D₄→⁷F_6,5,4,3,2&1) of Tb³⁺ doped material, one excitation wavelength of 229 nm was used. Structural characterization of these materials was carried out with an XRD and TEM measurements. The computed color coordinates suggest that both the phosphors have all desirable features for CRT screen applications.