Crystal structure refinement and luminescence properties of Ce3+ singly doped and Ce3+/Mn2+ codoped KBaY(BO3)2 for n-UV pumped white-light-emitting diodes

A series of novel Ce3+ singly doped and Ce3+/Mn2+ co-doped color-tunable KBaY(BO3)(2) phosphors were synthesized by a high-temperature solid-state reaction, and the crystal structures and luminescence properties were investigated in detail. The crystallographic cation sites occupancy of the doping Ce3+ and Mn2+ ions for KBaY(BO3)(2): Ce3+, Mn2+ samples were analyzed by the Rietveld refinement method. It was demonstrated that Ce3+ and Mn2+ ions can both enter into the two types of cation sites in the KBaY(BO3)(2) crystal lattice, with a slight tendency of occupancy for Ce3+ on Y3+ ion sites and Mn2+ on the Ba2+/K+ ion sites. By controlling Mn2+ ions content with a fixed Ce3+ concentration, the emission color of the phosphor varied from blue (0.160, 0.150) to pink-white (0.348, 0.272) and eventually to orange (0.490, 0.372). The critical energy transfer distance calculated by the concentration quenching theory was 16.52 angstrom and the energy transfer from Ce3+ to Mn2+ took place via a resonance-type dipole-dipole mechanism. By combining the single-phase KBa0.97Y0.97(BO3)(2): 0.01Ce(3+), 0.05Mn(2+) phosphor with an n-UV 370 nm InGaN chip, a phosphor-converted white LED lamp was successfully fabricated, producing a white light with a warm correlated color temperature of 4710 K and color coordinates of (0.347, 0.307).