Design of the Luminescence in Srlial3n4 : Eu2+ Via Structural Modulation

Red phosphor, with longer wavelength, is highly desirable for full-spectrum health lighting LEDs. Targeted red phosphors Sr 0.97-x Gd x LiAl 3 N 4 :0.03Eu 2+ (0≤x≤0.2) and Sr 0.82 Gd 0.15 LiAl 3-y Mg y N 4 :0.03Eu 2+ (0≤x≤1.0) have been designed from the initial model of SrLiAl 3 N 4 :Eu 2+ by structural modification. The correlations among structural evolution, crystal-field environment, and luminescence properties are elucidated. The substitution of Sr 2+ by Gd 3+ in Sr 0.97-x Gd x LiAl 3 N 4 :0.03Eu 2+ (0≤x≤0.2) leads to the enhanced crystal field splitting, larger Stokes shift, and increasing structural polyhedron distortion, consequently resulting in the spectral shift toward longer wavelength from 652 nm to 660 nm and broadening in emission spectra. Further, Mg, with smaller electronegativity, is also introduced to modify the centroid shift (ε c ) and crystal field splitting. As a result, Sr 0.82 Gd 0.15 LiAl 3-y Mg y N 4 :0.03Eu 2+ (0≤x≤1.0), with enhanced photoluminescence performance, can show a long-wavelength red emission at 675nm, making it more suitable for full-spectrum health lighting LEDs