Comprehensive study on thermal, structural, and luminescent properties of BiYWO6: Eu3+ phosphors synthesized by various methods

Abstract

Europium-activated bismuth yttrium tungstate (BYW: Eu³⁺) phosphors were synthesized by four various synthesis techniques such as solid-state reaction (SSR), sol–gel combustion (SGC), co-precipitation (CP), and hydrothermal (HT) methods. Relative investigations such as thermal, structural, morphological, and luminescence characterizations have been carried out to optimize the synthesis process of BYW:Eu³⁺phosphor. The TGA–DSC curves signify the endothermic/exothermic peaks and corresponding weight loss during heating. X-ray diffraction analysis and Rietveld refinement have been used to identify the phase and crystal structure of the undoped and doped BiYWO₆ sample. The field emission scanning electron microscope with energy-dispersive X-ray was carried out to examine the morphological and compositional behavior of the synthesized BYW: Eu³⁺phosphor. The luminescent spectral profiles indicate the strong absorption in the blue region (λ_ex = 465 nm) and intense emission in the red region (λ_em = 613 nm) ascribed to the ⁵D₀ → ⁷F₂ transition. The compared photoluminescence (PL) results signify that the phosphor synthesized by the CP method at calcination temperature 900 °C exhibits the strongest emission than the phosphor synthesized via other methods (SGC, SSR, and HT) and is especially two times higher than the phosphor synthesized by the SSR method. Further, the PL intensity enhanced with increasing activator concentration of Eu³⁺ ions up to 20 mol%. The calculated CIE chromaticity coordinates (0.654, 0.345) of 20.0 mol% Eu³⁺-doped BYW sample were situated in the red region, which is comparable with the commercially available red-emitting phosphors Y₂O₃:Eu³⁺ (0.645, 0.347) and Y₂O₂S:Eu³⁺ (0.647, 0.343). The average PL decay time of the synthesized phosphor was in the microseconds range. The obtained results suggest that the BiYWO₆ activated with Eu³⁺ ions phosphor synthesized by the CP method has distinctive PL characteristics with good morphology, which can be employed as an intense red-emitting component in photonics devices.