Effect of Gd3+ Ion Substitution on the Structural and Luminescence Properties of Ce3+-Doped YAG Phosphors.

In this study, we successfully synthesized Ce³⁺-activated gadolinium aluminum garnet phosphors using the sol–gel method, incorporating various Gd³⁺ substitution levels denoted by the chemical formula (Y_0.98−xGd_x)₃Al₅O₁₂:Ce: 0.06 (x = 0, 0.2, 0.4, 0.6). This study allowed us to discern the impact of Gd³⁺ substitution on garnet phase stability, crystallographic parameters, morphology, and luminescence properties. X-ray diffraction analysis revealed the pronounced sensitivity of the garnet phase to variations in Gd³⁺ content. Notably, discernible alterations were observed in both the reduction and shift of diffraction peaks, directly correlating with the percentage of Gd³⁺ doping. X-ray photoelectron spectroscopy revealed distinct core-level photoelectron and Auger transition peaks for yttrium, oxygen, aluminum, and gadolinium (Gd 3d, Gd 4d). Trace amounts of cerium were confirmed by the Ce 3d photoelectron peaks in both spectra, indicating the successful incorporation of the Ce dopant in the materials. Atomic force microscopy revealed that the incorporation of Gd resulted in significant changes, especially in granular formation. Field-emission scanning electron microscopy (FE-SEM) micrographs demonstrated the formation of agglomerated particles alongside a broad and asymmetrical particle size distribution. The particles exhibited an irregular morphology devoid of pores. Photoluminescence analysis revealed the distinctive yellow emission of Ce³⁺-doped YAG phosphors, attributed to the 5d–4f transition of the Ce³⁺ ion. Notably, an observed decrease in emission intensity was associated with an increase in Gd³⁺ content. [ABSTRACT FROM AUTHOR]