Refinement and luminescent properties of BaWO4: xSm3+yellow phosphor by a low temperature molten salt method

Abstract

In order to study the structure and analyze the performance, a series of BaWO4 with different Sm3+-doped concentration crystal particles were synthesized successfully via a low temperature molten salt method in LiNO3-KNO3 molten salt systems. For structural characterization, the phase and morphology of as-prepared powders were detected by XRD and SEM. It was clear that octahedron-type particles confirmed the scheelite-type tetragonal structure with space group I41/a. The effect of different contents of Sm3+ on the BaWO4 crystal structure was studied by Rietveld refinement techniques and the change of the optical band gap. As for the luminescent properties, the Sm3+ doped phosphors under 403 nm (6H5/2-4F7/2) excitation, exhibited characteristic luminescent of 4G5/2-6H5/2, 6H7/2, 6H9/2 transition of the Sm3+ ion. It was found that the optimal concentration involved in luminescence was about 3mol%. The critical distance between the Sm3+ ions was 1.852 nm. The mainly dominant mechanism of concentration quenching and corresponding CIE color coordinate were elaborated in details. These results indicated as-prepared phosphors could be suitable as single-doped yellow light emitters with only single-phased for solid state lighting applications.