Preparation of a novel violet-excitable Na3YSi2O7:Eu2+ green phosphor via salt-flux assistance and its luminescence properties

Abstract

Green-emitting phosphor Na₃YSi₂O₇:Eu²⁺ was prepared via salt-flux assistance for the first time. The effect of salt flux on the phase was studied and a pure phase Na₃YSi₂O₇:Eu²⁺ green phosphor was successfully prepared. The structure, photoluminescence properties and the concentration-driven bidirectional shift of excitation and emission spectra are discussed in detail. The excitation spectrum covers 300–450 nm, and the maximum value is shifted from 359 nm to 376 nm through concentration optimization, which matches with that of the violet LED chip. At the same time, the emission spectrum peak shifted from 543 nm to 530 nm. This bidirectional movement of excitation and emission spectra may be caused by lattice expansion caused by Eu²⁺ doping and concentration-driven lattice tendency occupation. Finally, a high-performance white LED with high Ra (92.3) and low CCT (4048 K) was achieved by encapsulating the synthesized Na₃YSi₂O₇:Eu²⁺ green phosphor with a 380 nm violet LED chip and commercial red and blue phosphors, confirming the prospects of the generated Na₃YSi₂O₇:Eu²⁺ green phosphor in WLED applications.