Synthesis, crystal structure and luminescence properties of a Y4Si2O7N2:Ce3+ phosphor for near-UV white LEDs

Abstract

A near-UV excited phosphor, Y₄Si₂O₇N₂:Ce³⁺, was synthesized using a solid-state reaction. The crystal structure and luminescence properties were studied. Y₄Si₂O₇N₂ crystallizes in a monoclinic unit cell with space group P2₁/c, lattice constants a = 7.5678(2) Å, b = 10.4529(1) Å, c = 10.7779(3) Å and β = 110.06°, and cell volume = 800.85(2) ų. The crystal structure of Y₄Si₂O₇N₂, featuring Si(O,N)₄ polyhedra, is provided, and there are four different Y³⁺ coordination environments with two different coordination numbers in the structure. Ce³⁺-doped Y₄Si₂O₇N₂ exhibited a broad emission band, and the maximum emission wavelength could be tuned from blue (λ_em = 450 nm) to green (λ_em = 515 nm) by increasing the concentration of Ce³⁺. The quantum efficiency was determined to be about 47%. The results show that Y₄Si₂O₇N₂:Ce³⁺ is a candidate for use as a conversion phosphor for near-UV white LED applications.