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Synthesis and Optical Properties of New Red Emitting Phosphor Li 3 BaSrGd 3‐x Eu x (MO 4 ) 8 for White LEDs
Author(s) -
Singh Kasturi,
Vaidyanathan Sivakumar
Publication year - 2016
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201601183
Subject(s) - phosphor , photoluminescence , tungstate , absorption edge , analytical chemistry (journal) , materials science , electric dipole transition , monoclinic crystal system , luminescence , absorption (acoustics) , europium , tungsten , light emitting diode , chemistry , band gap , crystal structure , optoelectronics , dipole , crystallography , magnetic dipole , organic chemistry , chromatography , metallurgy , composite material
Red emitting Li3BaSrGd3 ‐x Eu x (MO 4 ) 8 (M=W, Mo) phosphors with stratified scheelite structure have been synthesized by conventional solid state reaction. All the compositions crystallize in the monoclinic structure with space group C2/c. Host as well as the phosphors (Eu 3+ substituted) show broad absorption band in the UV to near UV region, due to the oxygen to molybdenum (absorption edge ∼360 nm, O 2− → Mo 6+ ) or tungsten (absorption edge ∼320 nm, O 2− → W 6+ ) charge transfer transition. The photoluminescence(PL) study of Eu 3+ substituted compositions show emission at ∼615 nm (due to the forced electric dipole (ED) 5 D 0 → 7 F 2 transition of Eu 3+ ion), which confirms that the Eu 3+ ion present in the non‐centrosymmetric site. In order to study the emission behaviour systematically the Judd‐Ofelt (J ‐ O) spectral intensity parameters were calculated. The Commission Internationale de l′Elcairage (CIE) colour coordinate values are well harmonized with the National Television Standard Committee (NTSC) standards. The presently synthesized tungstate phosphors have been used as reference for contrast between two. The entire compositions show better absorption in the near UV to blue region and emitting red light ∼615 nm indicates that this phosphor may find potential application as a red phosphor for white LED.