Enhanced photoluminescence of Li_3Ba_2Gd_3 (MoO_4)_8:Eu~(3+) red phosphor synthesized by mechanochemically assisted direct solid state reaction method at room temperature

摘要

For the first time, Li_3Ba_2Gd_(3-x)(MoO_4)_8:x Eu~(3+) (x = 0.01, 0.03, 0.05, 0.07 and 0.09 mol) red phosphor nanoparticles were prepared using the simple mechanochemically assisted direct solid state reaction method at room temperature and the luminescence effects as a function of Eu~(3+) ion concentration were studied. The characteristics of the phosphor materials were investigated using X-ray diffraction, Fourier transform infrared spectroscopy, photoluminescence and kinetic decay. For 7 mol% of Eu~(3+) concentration, the phosphor exhibits a strong excitation peak at 395 nm signifying a strong absorption. The PL emission spectra of Li_3Ba_2Gd_3 (MoO_4)_8:0.07 Eu~(3+) phosphors exhibited an intense peak at 615 nm (red) which relates to ~5D_o → ~7F_2 transition of Eu~(3+). The most favourable Eu~(3+) concentration in Li_3Ba_2Gd_3 (MoO_4)_8 phosphors for intensified red emission results for 7 mol% and above this concentration, the emission intensity falls off as a result of quenching effect. The CIE color coordinates of the Li_3Ba_2Gd_3 (MoO_4)_8:0.07 Eu~(3+) red phosphor coexist very well with the standard values of NTSC. The red emission intensity of the as prepared Li_3Ba_2Gd_3 (MoO_4)_8:0.07 Eu~(3+) red phosphor is 3.2 times better than that of the commercial Y_2O_2S:Eu~(3+) red phosphor prepared by the conventional solid state reaction method.