Optimization of Ce³⁺ concentration and Y₄MgSi₃O₁₃ phase in Mg²⁺‐Si⁴⁺ Co‐doped Ce: YAG ceramic phosphors

Abstract

As a promising replacement for nitride red phosphors, Ce: Y3(Mg1.8Al1.4Si1.8)O12 (Ce: YMASG) ceramic phosphors have attracted significant attention recently for their advantages in inorganic encapsulation and massive red‐shifting of Ce3+ emission. In this work, Ce: YMASG with different doping concentrations of Ce3+ and Al2O3, was fabricated by vacuum sintering to investigate its effects on the elimination of the impurity phase and the enhancement of the luminescent properties of white light‐emitting diodes (w‐LEDs). It was discovered that the emission wavelength redshifts from 592 to 606 nm as the Ce3+ concentration increases, while at 450 K, the emission intensity deteriorates from 0.47 to 0.36 of its initial value. The Rietveld analysis revealed the presence of an impurity phase of Y4MgSi3O13 with a concentration of 17.021 wt% in Ce: YMASG. With the introduction of Al2O3, the impurity phase was eliminated from the matrix completely, the emission peak shifted to a shorter wavelength, and the thermal stability was greatly improved. When the correlated color temperature was controlled at around 3000 K in the packaged w‐LEDs, the commission international de l'éclairage (CIE) chromaticity coordinates shifted toward the bottom left corner of the diagram with increasing concentration of Ce3+. Conversely, the luminous efficiency (LE) increased from 36 lm/W to 58.6 lm/W as the concentration of Al2O3 increased from 0 to 10 wt%, which demonstrated the application prospect of the fabricated phosphor in warm w‐LEDs.

Polyhedron Distortion and Site-Specific Rigidity in Garnet-Type Compounds

“…The garnet-type structure with multiple cationic sites is selected for consideration. The garnet-type luminescent materials have been widely applied in lighting, display, and biomedical fields. − It has three types of cationic polyhedra in the structure, with each of them accepting different dopant ions due to the size match. The garnet host itself presents excellent rigidity with a high Debye temperature over 600 K (Y 3 Al 5 O 12 ), but when the different sites are taken into account, the luminescence thermal quenching resistance seems contradictory to the intuitive impression that the smaller and more regular one would give better resistance.…”

Color Tunable Composite Phosphor Ceramics Based on SrAlSiN3:Eu2+/Lu3Al5O12:Ce3+ for High-Power and High-Color-Rendering-Index White LEDs/LDs Lighting

“…YAG:Ce phosphor ceramics have been extensively studied in recent years, showing high light conversion efficiency and thermal stability, but their low CRI and high CCT make them unsuitable for high-quality lighting applications [24]. To solve the problems, researchers have improved CRI by co-doping red emitting ions (Cr 3+ , Pr 3+ , Sm 3+ ) [25][26][27][28] or by partially replacing Y 3+ with different ions (Gd 3+ , Tb 3+ , Mg 2+ -Si 4+ ) [29][30][31] to induce the emission redshift of Ce 3+ in YAG, but this usually leads to a decrease in the luminous efficacy.…”