Synthesis, Structural and Fluorescence Investigations of Novel Li₂Ba₅W₃O₁₅:Sm³⁺ Phosphors for Photonic Device...

In the current study, Sm³⁺ ions doped Lithium Barium Tungstate (Li₂Ba₅W₃O₁₅) (LBW) phosphors with the ability to emit orange-red light were made using the traditional high-temperature solid-state reaction technique. The structure and phase of the as-synthesized phosphor samples were examined via X-ray diffraction (XRD) patterns. The diffraction peaks of the undoped LBW and Sm³⁺ ions doped LBW phosphors closely resemble those of the Joint Committee on Powder Diffraction Standards (JCPDS) pattern with card number 01-072-1717. Scanning electron microscopy (SEM) was employed for the analysis of the morphological characteristics of the synthesized phosphor material. Fourier Transform Infrared (FT-IR) spectroscopy was used to study several vibrational and molecular bands present in the host matrix. Using diffuse reflectance spectra (DRS), the optical band gap values (E_g) were evaluated by applying Tauc's method. The photoluminescence (PL) spectra characteristics at λ_ex = 336 nm indicate the emission of dopant ions (Sm³⁺) in the deep orange-red region corresponding to ⁴G_5/2 → ⁶H_5/2 transition (at 581 nm) with concentration quenching after 2 mol % of Sm³⁺ ions. Using the PL spectra, the CIE chromaticity coordinates of LBWS2.0 phosphor were estimated and found in the deep visible orange-red area, indicating the potential use of the prepared phosphor material for phosphor-converted white light emitting diodes (w-LEDs) applications. Double exponential behaviour can be seen in the PL decay spectral profiles obtained under λ_em = 581 nm and λ_ex = 336 nm. The experimental lifetimes (τ_exp) decrease as the concentration of Sm³⁺ ions rise. The temperature-dependent PL (TDPL) and activation energy results show that the as-synthesized phosphor has considerably superior thermal stability. The results of the current research contemplate us the applicability of Sm³⁺ ions doped LBW phosphor for photonic devices such as w-LEDs.