Structural and Optical Properties of Eu³⁺-DOPED Sr₃Y₂Ge₃O₁₂ as an Efficient Red Phosphor for WLED Application

This paper is aimed at investigating the structure and luminescence properties of Sr₃Y₂Ge₃O₁₂ activated by Eu³⁺ (SYGO:Eu³⁺), which were synthesized by using the sol-gel method. The synthesis was conducted at 1200°C for 8 h, with an optimal doping concentration of 5 mol% Eu³⁺. Under near-ultraviolet excitations at 395 nm, SYGO:x mol.% Eu³⁺ phosphors showed the red emission of Eu³⁺ (⁵D₀–⁷F₁) at 612 nm, and the photoluminescence intensity was highest at 5 mol.% Eu³⁺ doping. X-ray diff raction analysis of SYGO materials displays a single-phase structure that belongs to the Ia3d (230) space group. The result showed that the Eu³⁺ ion substitutes the asymmetrical location in the SYGO host, particularly the Sr²⁺ position, by calculating the ionic radius. In addition, the investigated red phosphors show high luminescence intensity and deep red emission. Thus, they show application potential as redemitting phosphor materials in white LEDs under near-ultraviolet excitations.