Red phosphors for W-LED applications

Project Report from the year 2015 in the subject Physics - Optics ST Anne''s College Of Engineering And Technology (St. Annes College of Engineering and Technology Panruti Tamilnadu India) language: English abstract: Trivalent rare-earth-ion-activated molybdate based phosphors have attracted great attention for solid-state lighting applications by virtue of their long lifetimes and efficient luminescence property. The rare-earth ions are represented by a partly filled 4f shell that is completely shielded by 5s2 and 5p6 orbitals. Therefore emission transitions provide sharp intense lines in the optical spectra [1 2]. The use of rare-earth element-based phosphor based on line-type ff transitions can narrow the emissions to the visible range resulting in high efficiency and a high-lumen equivalence. In recent years a flourishing care is concentrated on Li3Ba2Gd3-x(MoO4)8 host matrix for luminescent ions in the interest of their excellent chemical and thermal stability and favourable luminescence characteristics compared to the sulfide- and nitride-based materials. Moreover these are environmentally friendly as no toxic gases like sulphide are given out. Li3Ba2Gd3-x(MoO4)8 occur in monoclinic crystal system with space group C2/c in a disordered structure [3].For this research paper a series of Li3Ba2Gd3xPrx (MoO4)8 (x = 0.01 0.03 0.05 0.07and 0.09 mol) and Li3Ba2Gd3xSmx (MoO4)8 (x = 0.02 0.04 0.06 0.08 and 0.10 mol) red phosphors were synthesized by conventional solid state reaction method.