Synthesis and luminescence properties of NaLa(WO_4)_2:Eu~(3+) phosphors for white LED applications

摘要

Eu~(3+) activated NaLa(WO_4)_2 (NLW) red phosphors were synthesized via an ethylene glycol route at low temperature as 120°C for solid state lighting applications. X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), FT-IR, Raman, emission and excitation properties were studied for synthesized NLW phosphors. XRD analysis endorsed the formation of NaLa(WO_4)_2 with scheelite structure. For 9 mol% of Eu~(3+) concentration, the phosphor demonstrates an intensified narrow excitation peak at 394 nm indicating a strong absorption due to Eu~(3+) ion. The PL emission spectra of NaLa(WO_4)_2:0.09 Eu~(3+)phosphors exhibited an intense peak at 615 nm (red) which agrees to ~5D_0→~7F_2 transition of Eu~(3+) at the excitation wavelength of 394 nm. The CIE colour coordinates of NaLa(WO_4)_2:0.09 Eu~(3+) red phosphor accord very well with the standard values of NTSC. The sterling luminescent properties of NaLa(WO_4)_2:0.09 Eu~(3+) phosphor executes it as a potential red phosphor upon near-UV LED excitation.