An Efficient Blue (Na, Li) 2 Ba 6 Si 4 O 15 :Ce 3+ Phosphor for Near‐Ultraviolet‐Excited White LEDs

Tailoring the structure of a solid solution can effectively enhance the luminescence intensity and thermal stability of Ce 3+ ‐activated phosphors. In this work, a new blue phosphor Na 2 Ba 6 Si 4 O 15 :Ce 3+ was developed. The introduction of Li + into Na 2 Ba 6 Si 4 O 15 :Ce 3+ to form the Na 2‐ y Li y Ba 6 Si 4 O 15 :0.08Ce 3+ (0 ≤ y ≤ 0.7) solid solution system leads to a 150% increase in the luminescence intensity of the optimal sample ( y = 0.1) compared with the original phosphor, along with a significant red shift of the emission peak from 426 to 438 nm. At the same time, the sample exhibited excellent thermal stability (I 423 K /I 303 K = 90%) and a high internal quantum efficiency (IQE = 98.02%). Structural analysis revealed that Li + substitution effectively relieved the lattice distortion caused by Ce 3+ replacing Ba 2+ , shortened the Ce 3+ ‐O 2− bond length, and strengthened the nephelauxetic effect, which provided a structural basis for the improved luminescence performance. When it was mixed with commercial phosphors and encapsulated into a device, the color rendering index (Ra) was found to be 93.7, with a correlated color temperature of 5579 K, demonstrating excellent color reproduction ability. This work provides an effective reference for developing high‐efficiency, high‐thermal‐stability new phosphors by crystal structure engineering.