Defect-band reconstruction regulated by Zn²⁺/Eu³⁺ co-doping for color-tunable persistent luminescence in inverse-spinel Mg2-xZnxSnO4

Designed a defect-engineered Mg 2-x Zn x SnO₄:0.01Eu 3+ series (x = 0.01–1.00) based on inverse-spinel Mg 2 SnO 4 to elucidate the synergistic roles of Zn²⁺ and Eu³⁺ in tuning photoluminescence (PL) and persistent luminescence (PersL).The phosphors were synthesized via a high-temperature solid-state reaction and characterized by XRD (Rietveld refinement), XPS, PL/PLE spectroscopy, PersL decay measurements, and three-dimensional thermoluminescence (TL; 290–647   K; 3   K·s⁻¹). As Zn content increases, both the PL and PersL bands red-shift from 500   nm to 550–555   nm, and the emission intensity peaks at x = 0.30.XPS verifies that Sn⁴⁺, Zn²⁺, and Eu³⁺ are the predominant valence states. General-order kinetics (GOK) fitting of the TL curves indicates a shift in the trap population toward medium-to-deep levels, accompanied by stronger carrier retrapping. Mechanistically, Zn²⁺ increases oxygen-vacancy-related defects and lowers defect-associated energy levels. In contrast, aliovalent Eu³⁺ primarily modulates the trap distribution via charge compensation, rather than serving as the main emitting center. The composition at x=0.30 achieves an optimal balance between trap population and defect concentration, enabling a bright, color-tunable afterglow.