Tailoring afterglow properties of polychromatic long-persistent LiMg Sr4--2(BO3)3: y Eu2+ phosphor by codoping with Dy3+ or Nd3+

Herein, redshifted long persistent LiMgxSr4-x-2y(BO3)3: y Eu2+, Dy3+(Nd3+) phosphors are successfully prepared in a reducing atmosphere using a high-temperature solid-state process. The emission of phosphors displays redshift characteristics between 633 and 660 nm with an increase in the concentration of Mg2+ substitution, primarily attributed to enhanced energy level splitting of Eu2+ after Mg2+ replacement. The afterglow performance of LiMg0.6Sr3.4-2y (BO3)3: y Eu2+, Dy3+ (Nd3+) samples is enhanced with increase in concentrations of the doped rare-earth ions. An optimal concentration of 6%, the best afterglow performance was achieved because high concentration traps with suitable energy levels were developed; this was confirmed using afterglow measurements and thermoluminescence tests. The Nd3+ codoped phosphor shows improved afterglow performance compared with the Dy3+ codoped phosphor at the same doping concentration, which can be attributed to Nd3+ can easily be incorporated into the borate lattice that generates electron traps with high concentration.