Phase formations and red-luminescence enhancement of Eu3+-activated NaBaY(BO3)2 phosphors

Eu3+-activated Na1-xKxBaY(BO3)(2) (x = 0.1-1.0) phosphor was prepared via facile solid-state reaction ceramic method. The structural Rietveld refinements were completed to confirm the phase formations. The luminescence properties were reported such as photoluminescence excitation (PLE) and emission (PL) spectra, decay lifetime, experimental quantum efficiency (QE) and thermal stabilities. The phase formations and the luminescence properties of the phosphors have a dependence on the K+-substituting for Na+ in the lattices. The results showed that Na1-xKxBaY0.5Eu0.5(BO3)(2) (x = 0.1-1.0) phosphors formed the trigonal NaBaY(BO3)(2) single phase (Na-phase, space-group of R-3, No. 148). Increasing the K+-substituting for Na+ (x <= 0.3) induced the appearance of KBaY(BO3)(2) phase (K-phase, space-group of R-3 m, No. 166) together with the Na-phase (0.3 < x < 0.6). Heavily K-substituted samples crystallized into a single K-phase. Luminescence characteristics of Eu3+ ions were investigated on the evolution of the substituting-level. It was observed that the phosphors presented the improved emission intensity and thermal stability in the mixed phases.