Luminescent properties of (Na,M)AlSiO4:Eu²⁺ phosphors (M = Li, K, Mg, Ca)

A series of (Na_{1-x or x/2}M_x)AlSiO₄:0.1Eu²⁺ phosphors (M = Li⁺, K⁺, Mg²⁺, Ca²⁺) were synthesized at 1200°C under reducing atmosphere by a liquid phase precursor (LPP) method in order to achieve new luminescent properties with the different metals in x = 0.1 ~ 0.4 concentrations. The main photoluminescence excitation (PLE) and photoluminescence (PL) spectra of the obtained phosphors were broadly located from 320 nm to 410 nm and from 485 nm to 548 nm, respectively. These excitation spectra of Li-NAS:Eu²⁺, K-NAS:Eu²⁺, Ca-NAS:Eu²⁺ and Mg-NAS:Eu²⁺ phosphors showed a red-shift compared with the standard NaAlSiO₄:Eu²⁺ (NAS:Eu²⁺) phosphor. The main emission spectra were centered at 480 nm (blue), 544 nm (green), 548 nm (yellowish green), respectively, which suggested their prospective potential in application of near-UV pumped white light-emitting diode (n-UV WLED).