A Blue Light–Excited Broadband Chartreuse‐Emitting LuMg ₂ Al ₃ Si ₂ O ₁₂ :Ce ³⁺ Garnet Phosphor With High Thermal Stability for High‐Performance White LEDs

High-brightness and thermally stable chartreuse-emitting phosphors are highly desirable for high-quality phosphor-converted white light-emitting diodes (pc-LEDs). In this article, a new chartreuse phosphor, Lu_(1-x)Mg₂Al₃Si₂O₁₂:xCe³⁺ (LMASO:xCe³⁺), was synthesized via a high-temperature solid-state reaction. X-ray diffraction and Rietveld refinement reveal that LMASO phosphors crystallize in the cubic system (Ia <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:mover><mml:mn>3</mml:mn> <mml:mo>¯</mml:mo></mml:mover> </mml:mrow> <mml:annotation>$$ \overline{3} $$</mml:annotation></mml:semantics> </mml:math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:mover><mml:mn>3</mml:mn> <mml:mo>-</mml:mo></mml:mover> </mml:mrow> <mml:annotation>$$ \overline{3} $$</mml:annotation></mml:semantics> </mml:math> d). The optimal doping concentration of Ce³⁺ in LMASO is 10 mol%, which is higher than that of other Ce³⁺-doped garnet phosphors. Its broad excitation band peaking at 429 nm matches well with the emission from commercial blue LED chips. Under 429 nm excitation, the LMASO:Ce³⁺ phosphor exhibits a wide asymmetric emission band ranging from 450 to 650 nm. The high activation energy (0.334 eV) indicates a good thermal quenching resistance. A white LED device was fabricated by combining a 450nm blue LED chip with the LMASO:0.10Ce³⁺ chartreuse phosphor and a commercial CaAlSiN₃:Eu²⁺ red phosphor. This device emits bright warm-white light with excellent CIE color coordinates (0.3978, 0.3959), a low correlated color temperature (CCT = 3500 K) and a high color rendering index (Ra = 95.7). The results demonstrate that LMASO:Ce³⁺ phosphor is a promising candidate for pc-LEDs.