Synthesis, Structural and Fluorescence Investigations of Novel LiBaWO:Sm Phosphors for Photonic Device Applications.

In the current study, Sm ions doped Lithium Barium Tungstate (LiBaWO) (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 Sm 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) were evaluated by applying Tauc's method. The photoluminescence (PL) spectra characteristics at λ = 336 nm indicate the emission of dopant ions (Sm) in the deep orange-red region corresponding to G → H transition (at 581 nm) with concentration quenching after 2 mol % of Sm 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 = 581 nm and λ = 336 nm. The experimental lifetimes (τ) decrease as the concentration of Sm 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 Sm ions doped LBW phosphor for photonic devices such as w-LEDs.