Jiayue Sun

Dy ³⁺ ‐activated Na ₃ YSi ₂ O ₇ phosphors have been prepared via a solid‐state reaction technique and may be used as a component of white light‐emitting diodes. X ‐ray diffraction analysis demonstrates the single‐phase formation and the substitution of activator ions for Na ₃ YSi ₂ O ₇ : Dy ³⁺ materials. The emission of Dy ³⁺ in different Y ³⁺ lattice sites exhibits blue ( ⁴ F _9/2 → ⁶ H _15/2 ) and yellow ( ⁴ F _9/2 → ⁶ H _13/2 ) lights, which function together to generate white light. The optimum doping concentration is 3 mol% and energy transfer between Dy ³⁺ ions has been validated to be a resonant type via an electric dipole–dipole mechanism. The temperature‐dependent luminescent properties from 25°C to 400°C are studied, and the blue emission increases as a function of the temperature. This interesting phenomenon is proposed to be the result of the model in the configurational coordination diagram. The present investigation reveals the potential application for Na ₃ YSi ₂ O ₇ : Dy ³⁺ system in solid‐state lighting.

A novel near-infrared (NIR) downconversion (DC) phosphor KSrPO₄:Eu²⁺, Pr³⁺ is synthesized by the conventional high temperature solid-state reaction. The Eu²⁺ acts as an efficient sensitizer for Pr³⁺ in the KSrPO₄ host. With broadband near-ultraviolet light excitation induced by the 4f→5d transition of Eu²⁺, the characteristic NIR emission of Pr³⁺, peaking at 974 nm and 1019 nm due to ³P₀→¹G₄ and ¹G₄→³H₄ transitions, is generated as a result of the energy transfer from Eu²⁺ to Pr³⁺. The luminescence spectra in both the visible and the NIR regions and the decay lifetime curves of Eu²⁺ prove the energy transfer from Eu²⁺ to Pr³⁺. This Eu²⁺ and Pr³⁺ co-doped KSrPO₄ phosphor may be a promising candidate to modify the spectral mismatch behavior of crystalline solar cells and sunlight.