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A promising RVO 4 :Eu 3+ ,Li + @SiO 2 (R = Gd, Y and Gd/Y) red‐emitting phosphor with improved luminescence (cd/m 2 ) and colour purity for optical display applications
Author(s) -
Rambabu Urlagaddala,
Munirathnam Nagegownivari Ramachandra,
Reddy Busireddy Sudhakar,
Chatterjee Sandip
Publication year - 2016
Publication title -
luminescence
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.428
H-Index - 45
eISSN - 1522-7243
pISSN - 1522-7235
DOI - 10.1002/bio.2936
Subject(s) - phosphor , luminescence , analytical chemistry (journal) , photoluminescence , scanning electron microscope , materials science , crystallinity , fourier transform infrared spectroscopy , transmission electron microscopy , chemistry , optics , nanotechnology , optoelectronics , physics , chromatography , composite material
Red emission intensity was optimized in three stages, by investigating the effects of: (i) host composition (Gd, Y and Gd/Y), (ii) codoping Li + as a sensitizer and, finally, (iii) with a SiO 2 shell coating as a protecting layer. Lanthanide vanadate powder phosphors were synthesized using a modified colloidal precipitation technique. The effects of SiO 2 coating on phosphor particles were characterized using scanning electron microscopy (SEM)‐EDAX, transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and photoluminescence (PL) measurements. An improvement in the PL intensity on Li codoping was due to improved crystallinity, which led to higher oscillating strengths for the optical transitions, and also a lowering of the inversion symmetry of Eu 3+ ions. Red emission intensity due to 5 D 0 → 5 D 2 transition of the phosphor Y 0.94 VO 4 :Eu 3+ 0.05 ,Li + 0.01 was enhanced by 22.28% compared with Y 0.95 VO 4 :Eu 3+ 0.05 , and was further improved by 58.73% with SiO 2 coating. The luminescence intensity ( I ) and colour coordinates ( x , y ) of the optimized phosphor Y 0.94 VO 4 :Eu 3+ 0.05 ,Li + 0.01 @SiO 2 , where I = 13.07 cd/m 2 and ( x = 0.6721, y = 0.3240), were compared with values for a commercial red phosphor (Y 2 O 2 S:Eu 3+ ), where I = 27 cd/m 2 and ( x = 0.6522, y = 0.3437). The measured colour coordinates are superior to those of the commercial red phosphor, and moreover, match well with standard NTSC values ( x = 0.67, y = 0.33). Copyright © 2015 John Wiley & Sons, Ltd.