Abstract
In this paper, yttrium aluminium garnet (YAG) nano-phosphors are single or co-doped with Ce3+ and Eu3+ rare earth ions in different concentrations. The precursors were prepared by solid state reactions in repeated heating cycles from 1300 to 1600 °C. The crystalline phase was confirmed by an X-ray powder diffraction (XRD) analysis. The rare earth dopant ions were successfully integrated into the YAG host lattice without changing the original structure. The cubic phase of the synthesized phosphors was confirmed by Rietveld refinement. The microstructure and composition of the pure and doped YAG samples were studied in detail using TEM, HRTEM, and EDX elemental composition analyses. The photoluminescence properties of the YAG:xCe3+ (x = 0.01, 0.05, 0.07, 0.09) and YAG:0.05Ce3+, xEu3+ (x = 0.01, 0.02, 0.03, 0.04, 0.05) phosphors were also investigated in detail. The obtained optimal doping molar concentrations of the Ce3+ and the Eu3+ions were 0.07 and 0.02 mol%, respectively. The YAG:xCe3+ exhibited a typical 5d-4f emission broadband with a maximum peak located at 543 nm. We detected a variation of the Ce3+ emission intensity with varying Eu3+ concentration, which may be due to the energy transfer from Ce3+ to Eu3+. The optimum CIE chromaticity coordinates (x, y) of YAG:0.07Ce3+ and YAG:0.05Ce3+, xEu3+[x = 1%], were (0.310, 0.345) and (0.3243, 0.3730), respectively, which were close to the NTSC standard values. The CCT values indicated that for the concentration of Eu3+ (1%), the white light was daylight to cool daylight (5485–6847 K), and for the concentration of Eu3+ (2%), the white light was cool white to daylight (4797–5112 K).