Different alkali carbonates on the microstructure and photoluminescence properties of SrWO 4 :Tb 3+ phosphors

In this research terbium-doped strontium tungsten oxide samples were synthesized using solid-state synthesis method. It was found through X-Ray powder diffraction (XRD) that the samples belong to the tetragonal crystal system and have the space group I4 ₁ /a. The scanning electron microscope (SEM) images indicate that the Na, K, W and Tb atoms are uniformly distributed throughout the samples. Photoluminescence (PL) measurements were applied for sample characterization. All of them exhibited green emission with highest peak at 545 nm attributable to ⁵ D ₄ → ⁷ F ₅ transition. The highest emission intensity was observed in SrWO ₄ :0.4%Tb sample while higher doping levels resulted in decrease of the PL intensities due to concentration quenching. Samples with additional alkali metal ions for charge compensation were also prepared and their PL properties were measured. Doping with 0.5 mol% K ⁺ ions yielded a 1.8-fold increase in mechanical strength, a 4.4-fold enhancement in operational lifespan, and a 153% improvement in quantum yield. These results indicate that SrWO ₄ :0.4%Tb,0.5%K materials have great potential application as green phosphors in LEDs.