Enhancement of persistent luminescence of ZnTa₂O₆:Pr³⁺ by addition Li⁺, Na⁺, K⁺ and Cs⁺ ions

Enhancement of the persistent emission was achieved by co-doping ZnTa₂O₆:Pr³⁺ with Li⁺, Na⁺, K⁺ or Cs⁺ ions. Phase pure samples were synthesised and it was confirmed by the X-ray diffraction pattern which matches that of the standard data. Incorporation of the co-dopant ions introduced strain into the phosphor, which increased with an increase in the ionic radius of the co-dopant ion. The scanning electron microscope image shows that the particles were agglomerated, and the surface images obtained using the Time of flight secondary ion mass spectroscopy showed that the dopant and the co-dopant ions in the phosphor were homogeneously distributed. The persistent emission was enhanced by the co-dopant ions as shown by the lifetime values calculated from the phosphorescence decay curves, and the corresponding electron trapping centres were quantified by thermoluminescence reader.