Intrinsic Defect Engineering in Eu³⁺ Doped ZnWO₄ for Annealing Temperature Tunable Photoluminescence

Eu³⁺ doped ZnWO₄ phosphors were synthesized via the co-precipitation technique followed by subsequent thermal annealing in the range of 400⁻1000 °C. The phase, morphology, elemental composition, chemical states, optical absorption, and photoluminescence (PL) of the phosphors were characterized by X-ray diffraction, scanning electron microscopy, dispersive X-ray spectroscopy, X-ray photoelectron spectrometry, diffuse UV⁻vis reflectance spectroscopy, PL spectrophotometry, and PL lifetime spectroscopy, respectively. It is found that the PL from Eu³⁺ doped ZnWO₄ is tunable through the control of the annealing temperature. Density functional calculations and optical absorption confirm that thermal annealing created intrinsic defects in ZnWO₄ lattices play a pivotal role in the color tunable emissions of the Eu³⁺ doped ZnWO₄ phosphors. These data have demonstrated that intrinsic defect engineering in ZnWO₄ lattice is an alternative and effective strategy for tuning the emission color of Eu³⁺ doped ZnWO₄. This work shows how to harness the intrinsic defects in ZnWO₄ for the preparation of color tunable light-emitting phosphors.