Luminescence characteristics and J-O analysis of BaWO4:3%Sm3+ crystal for yellow phosphors

Yellow emitting BaWO4:3% Sm3+ phosphor was synthesized by a low-temperature molten salt method in LiNO3-KNO3. The prepared powders were characterized by X-ray diffraction (XRD), optical absorption and photoluminescence (PL) techniques. The crystal structure and related parameters were analyzed in detail by Rietveld refinement. The Judd-Ofelt (J-O) theory, which is used to explain the yellow emission mechanism and examine its luminescence properties, was applied to analyze the oscillator strengths, branching ratios, radiative lifetimes and transition probabilities of the BaWO4:3%Sm3+ system. PL spectrum presented three prominent emission bands located at 562, 599 and 645 nm which are corresponding to the transitions from 4G5/2 to 6H5/2, 6H7/2 and 6H9/2, respectively. The CIE coordinates and correlated color temperature of the sample were also evaluated.