Extension of Spectral Shift Controls from Equivalent Substitution to an Energy Migration Model Based on Eu/Tb-Activated BaSrGdLuNa(PO)F Phosphors.

Single-phase phosphors with tunable emission colors are crucial to develop high-performance white light-emitting diodes since they are valuable to improve the energy efficiency, color rendering index, and correlated color temperature. Most of the studies have been conducted to control the spectral shifts via a polyhedral distortion or chemical unit cosubstitution strategy. The combination of host optimization and dopant activator design in a single-phase phosphor system is very rare. Herein, a partial substitution strategy of [Ba-Gd] by [Sr-Lu] has been employed in BaSrGdLuNa(PO)F/5% Eu ( = 0-0.40) phosphors. Also, the energy migration from Eu to Tb ions has been investigated in as-prepared samples. Consequently, the emitted signal is observed to shift from 470 to 575 nm derived from equivalent substitutions, which is attributed to specific performance by the emission profile of Eu, and such results are closely related to splitting of the crystal field and energy transfer among various luminescent centers. Moreover, the tunable yellowish-green emitting material has been assembled by incorporating ion pairs (Eu → Tb) into the BaSrGdLuNa(PO)F, and their relative ratios are varied. The corresponding Eu → Tb energy migration process is assigned to be the dipole-quadrupole interaction by the Inokuti-Hirayama model. This work provides rational guidance for the design and discovery of new products with tunable emission colors, originating from the cosubstitution strategy and energy conversion model.