Crystal Field Engineering Yields New 3D Layered Solid Solution Phosphors (Ca/Sr)₄MgAl₂Si₃O₁₄:Eu²⁺ for White-Light-Emitting Diode Full-Spectrum Lighting

The cation-equivalent substitution strategy has the ability to manipulate the luminescence color of phosphors and enhance their overall luminescence performance. A series of novel yellow feldspar-type 3D layered phosphors (Ca1–ySry)4MgAl2Si3O14:xEu2+ were synthesized using a high-temperature solid-state reaction. The solid solution phosphors belong to a tetragonal crystal system with a space group of P4̅21m and cell parameters of a = b = 7.75407–7.91794 Å, c = 5.04299–5.22543 Å, and V = 303.166–327.602 Å3. Under near-ultraviolet (n-UV) excitation, the luminescence color of the phosphor undergoes modulation from yellow-green (530 nm) to blue (467 nm) as the Sr2+ ion substitution ratio increases. This modulation is attributed to the gradual decrease in crystal field splitting energy. Additionally, both the Stokes shift and the full width of the luminescence spectra decrease. Furthermore, there is an increase in the quantum yield (QY) from 45.50 to 60.73%. Finally, the fabricated white-light-emitting diode devices emitted warm white light and achieved high Ra (Ra = 94, 96.6, 92.7) and low correlated color temperature (CCT = 3486, 3430, 3788 K), indicating that the prepared solid solution phosphors can be used as candidate materials for WLED lighting.