Synthesis and photoluminescent properties of orange-emitting Sm3+-activated KPb4(PO4)3 phosphor for LEDs

A series of Sm3+-doped KPb4(PO4)3 phosphors have been successfully synthesized by high-temperature solid-state reaction method, and the structure, morphology and luminescent properties were investigated. The SEM images suggest that the prepared phosphor has an irregular morphology with a diameter of about 10 ~ 20 μm. Under near-ultraviolet (NUV) light (404 nm) excitation, all prepared phosphors KPb4-xSmxP3O12 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1, 0.15, 0.2, 0.3, 0.4 and 0.5) show the characteristic f → f emission bands of the Sm3+ activator. And the emission intensities have an upward trend with increasing the Sm3+ concentration when x is lower than 0.1. By monitoring 598 nm emission, the excitation spectrum of KPb3.9Sm0.1(PO4)3 contains a series of sharp bands in the range of 250 ~ 500 nm, which matches well with the NUV LED chip. The CIE coordinates of KPb3.9Sm0.1(PO4)3 phosphor was evaluated to be (0.5714, 0.4253), corresponding to orange color with a high color purity of about 90%.