White-light-emitting diodes of UV-based Sr3Y2(BO3)4:Dy3+ and luminescent properties

The Sr3Y2(BO3)4:Dy3+ phosphor was synthesized by high temperature solid-state reaction method, and the luminescence characteristics were investigated. The emission spectrum of Sr3Y2(BO3)4:Dy3+ phosphor shows three bands centered at 488 nm, 575 nm and 665 nm under 365 nm excitation, which originate from the transitions of 4F9/2–6H15/2, 4F9/2–6H13/2 and 4F9/2–6H11/2 of Dy3+, respectively. The excitation spectrum for 575 nm emission has several bands centered at 343 nm, 378 nm, 432 nm and 473 nm, which is coupled well with the emission of UV LED (350–410 nm) and blue LED (450–470 nm). The effect of Dy3+ concentration on the emission intensity of Sr3Y2(BO3)4:Dy3+ phosphor was researched and the results indicate that the 575 nm emission intensity firstly increases with increasing the Dy3+ concentration, then decreases. And the ratio (Y/B) of 575 nm emission intensity to 488 nm emission intensity increases with increasing the Dy3+ concentration. The CIE chromaticity of UV LED (370 nm)-based Sr3Y2(BO3)4:Dy3+ is (x = 0.2997, y = 0.3142), and the correlated color temperature (Tc) is 5896 K.