Structure modification and luminescence regulation in new violet light excitable Sr(2−y)BayY4La4(SiO4)6O2:xEu2+ phosphors via cation substitution†

Cyan-emitting phosphors are urgently needed to address the “cyan gap” in artificial full-spectrum lighting. In this research, a series of Sr_(2−y)Ba_yY₄La₄(SiO₄)₆O₂:xEu²⁺ (0.005 ≤ x ≤ 0.08, 0.0 ≤ y ≤ 2.0) phosphors with tunable luminescence was synthesized. Through cation regulation, the luminescence color of Sr_(2−y)Ba_yY₄La₄(SiO₄)₆O₂:xEu²⁺ can be adjusted from yellow to cyan. Crystal structure analysis revealed that Eu²⁺ ions simultaneously occupy [Sr1/Ba1Y1La1] and [Sr2/Ba2Y2La2] sites, resulting in multiple luminescence centers and a broadened emission spectrum. With increasing Ba²⁺ ion concentration, the PLE spectrum was red-shifted from 337 nm to 372 nm, and the excitation intensity in the violet region was significantly enhanced, making it more compatible with violet LED chips. Meanwhile, the PL spectrum was blue-shifted from 543 nm to 496 nm with increasing Ba²⁺ concentration, accompanied by an increase of about 10 times in the excitation and emission intensity. The optimized Ba₂Y₄La₄(SiO₄)₆O₂:0.02Eu²⁺ phosphor can be excited by violet light and emits bright cyan light effectively, which can be used to fill the “cyan gap”. Eventually, a series of white LED devices was manufactured by combining the as-prepared luminescence-tunable phosphors with commercial phosphors. Among them, the 410 nm violet LED chip-based WLED(Ba₂) device comprising Ba₂Y₄La₄(SiO₄)₆O₂:0.02Eu²⁺ exhibited the best electroluminescence performance, increasing the color rendering index from 82.0 to 98.6, verifying the compensation effect of the Ba₂Y₄La₄(SiO₄)₆O₂:Eu²⁺ phosphor on cyan light.