A white light emitting Li₂SiO₃:Tb³⁺, Eu³⁺ phosphors: structural, thermal, spectroscopic properties and energy transfer mechanism

In this communication, a series of Li₂SiO₃:0.04Tb³⁺, yEu³⁺ (y = 0.01, 0.02, 0.03, 0.04, and 0.05 mol) phosphors has been prepared by solid state reaction method at 950℃ in an air and their crystal structures, luminescent characteristics, energy transfer mechanism and lifetime, were thoroughly examined. An orthorhombic structure is confirmed by the powder X-ray diffraction (PXRD) spectra. The PXRD data was further refined using the Rietveld refinement process. When stimulated at 378 nm, a sequence of distinctive emissions of Li₂SiO₃:0.04Tb³⁺, yEu³⁺ phosphors were seen in the emission spectra at approximately 541 nm (⁵D₄→⁷F₅ transition), 593 nm (⁵D₀→⁷F₁ transition), and 617 nm (⁵D₀→⁷F₂ transition). The crystal distance (R_c) was determined using the concentration quenching method, and it was shown that the energy transfer process between Tb³⁺ and Eu³⁺ was of the resonant type through a dipole–dipole (d-d) mechanism. Under the UV excitation (378 nm); the optimized Li₂SiO₃:0.04Tb³⁺, 0.04Eu³⁺ materials demonstrates improved thermal stability up to 150^oC compared to similar findings. White light emission can be tuned out of the Li₂SiO₃:Tb³⁺, Eu³⁺ phosphors, according to the CIE chromaticity coordinates system. The possible luminescence mechanism involved has systematically been investigated and discussed. The photometric results indicate that the synthesized phosphors have a promising potential for solid state lighting.