Remarkable structure and luminescence regulation of a Gd2LuAl5O12:Ce garnet phosphor with a Ca2+/Si4+ pair for high-quality w-WLED lighting
Doping Gd2LuAl5O12:Ce with a Ca2+/Si4+ pair produced a series of Gd1.97−xLuCaxAl5−xSixO12:0.03Ce (x = 0.0–1.2) garnet new phosphors, and remarkable regulation of the crystal structure and Ce3+ luminescence was achieved. Rietveld refinement and spectral analysis revealed that greater incorporation of Ca2+/Si4+ led to a higher lattice rigidity by cell contraction, a narrower bandgap, a longer average bond length/less distortion of the [CeO8] dodecahedron and decreased centroid shift/crystal field splitting of the Ce3+ 5d energy level. A blue-shifted 4f–5d1 transition, a narrower emission band, improved thermal stability of luminescence and a shorter fluorescence lifetime were observed with increasing Ca2+/Si4+ content. Applying the yellowish-green-emitting Gd0.77LuCa1.2Al3.8Si1.2O12:0.03Ce optimal phosphor (x = 1.2), together with a commercial CaAlSiN3:Eu red phosphor, in 450 nm-excited LED lighting produced a low CCT of ∼3625 K and a high CRI/R9 of ∼95.2/94.8, indicating that the phosphor has application potential in high-performance w-WLED.
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