title: A promising RVO4:Eu(3+), Li(+)@SiO2 (R = Gd, Y and Gd/Y) red-emitting phosphor with improved luminescence (cd/m(2)) and colour purity for optical display applications.
abstract: 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 SiO2 shell coating as a protecting layer. Lanthanide vanadate powder phosphors were synthesized using a modified colloidal precipitation technique. The effects of SiO2 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)D0  → (5)D2 transition of the phosphor Y0.94VO4:Eu(3+)0.05, Li(+)0.01 was enhanced by 22.28% compared with Y0.95VO4:Eu(3+)0.05, and was further improved by 58.73% with SiO2 coating. The luminescence intensity (I) and colour coordinates (x, y) of the optimized phosphor Y0.94VO4:Eu(3+)0.05, Li(+)0.01@SiO2, where I = 13.07 cd/m(2) and (x = 0.6721, y = 0.3240), were compared with values for a commercial red phosphor (Y2O2S: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).
authors.affiliation: Centre for Materials for Electronics Technology (C-MET), Department of Electronics & IT (DeitY), IDA phase - III, Cherlapally, Hyderabad, 500051, A.P, India.
authors.forename: Urlagaddala
authors.initials: U
authors.lastname: Rambabu
authors.affiliation: Centre for Materials for Electronics Technology (C-MET), Department of Electronics & IT (DeitY), IDA phase - III, Cherlapally, Hyderabad, 500051, A.P, India.
authors.forename: Nagegownivari Ramachandra
authors.initials: NR
authors.lastname: Munirathnam
authors.affiliation: Department of Physics, S. V. Degree College, Kadapa, India.
authors.forename: Busireddy Sudhakar
authors.initials: BS
authors.lastname: Reddy
authors.affiliation: Dept of Electronics & IT, Materials and components Division, New Delhi, India.
authors.forename: Sandip
authors.initials: S
authors.lastname: Chatterjee
mesh_terms: D003116:Color; D005063:Europium / Q000737:chemistry*; D005682:Gadolinium / Q000737:chemistry*; D008094:Lithium / Q000737:chemistry*; D049449:Luminescence; D010316:Particle Size; D013499:Surface Properties; D014638:Vanadates / Q000737:chemistry*; D015019:Yttrium / Q000737:chemistry*
chemical_list: D014638:Vanadates; D005063:Europium; D015019:Yttrium; D008094:Lithium; D005682:Gadolinium
keywords: Eu, Li-co-doped; colour purity; lanthanide vanadates; luminescence intensity; red phosphors