Cyan, deep red and white light emission generated by SrLaGa3O7:Bi3+, SrLaGa3O7:Mn4+ and SrLaGa3O7:Bi3+/Mn4+ phosphors

Abstract

In this work, Bi3+-doped, Mn4+-doped, and Bi3+/Mn4+ co-doped SrLaGa3O7 (SLGO) phosphors were synthesized by solid-state reactions. Crystal structures, composition and optical properties of these phosphors were studied. Phase purity of SLGO: Bi3+/Mn4+ phosphor was characterized by X-ray diffraction. Elements of SLGO: Bi3+/Mn4+ phosphors were revealed by XPS measurements. Absorptive abilities of the synthesized phosphors were characterized by UV–vis absorption measurements. The UV–vis absorption and excitation spectra showed that the phosphors can be excited by ultraviolet and near ultraviolet light. Upon the excitation at 365 nm, SLGO: Bi3+ and SLGO: Mn4+ phosphors showed cyan and deep red emission, respectively. Energy transfer from Bi3+ to Mn4+ occurred in SLGO: Bi3+/Mn4+ phosphors. The Bi3+→Mn4+ energy transfer process was revealed by luminescence spectra and fluorescence decay curves. The emission of SLGO: Bi3+/Mn4+ phosphors could be tuned by changing excitation wavelength and Bi3+/Mn4+ doping concentrations. Under the excitation at 365 nm, warm white light was generated by SLGO: 0.005Bi3+/0.002Mn4+ phosphor, which has the CIE coordinates of (0.3697, 0.2864) and the correlated color temperature of 3295 K. Under the excitation at 360 nm, SLGO: 0.005Bi3+/0.0015Mn4+ phosphor showed warm white light with the CIE coordinates of (0.3447, 0.2616) and the correlated color temperature of 4309 K. The values of activation energy were 0.2698 eV (465 nm) and 0.4283 eV (714 nm) for SLGO: 0.005Bi3+, 0.0015Mn4+ phosphor. The above results implied that SLGO: Bi3+/Mn4+ phosphors have potential applications in warm WLED lighting.