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

Abstract

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 (Eg) were evaluated by applying Tauc's method. The photoluminescence (PL) spectra characteristics at λex = 336nm indicate the emission of dopant ions (Sm3+) in the deep orange-red region corresponding to 4G5/2 → 6H5/2 transition (at 581nm) with concentration quenching after 2mol % of Sm3+ ions. Using the PL spectra, the CIE chromaticity coordinates of LBWS2.0 phosphor were estimated and found in the deep visible orange-redarea, 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 spectralprofiles obtained under λem = 581nm and λex = 336nm. The experimental lifetimes (τexp) 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.