Eu²⁺-Doped Ca₄Y₃Si₇O₁₅N₅ Phosphor with High Thermal Stability and Pressure Sensitivity for Dual-Functional...

A novel green-light-emitting silicon-based oxynitride phosphor Ca₄Y₃Si₇O₁₅N₅:Eu²⁺ with low thermal quenching and ideal pressure sensitivity is reported. The Ca_3.99Y₃Si₇O₁₅N₅:0.01Eu²⁺ phosphor can be efficiently excited by 345 nm ultraviolet light and shows very low thermal quenching (integrated and peak emission intensities at 373 and 423 K were 96.17, 95.86, and 92.73, 90.66% of those at 298 K, respectively). The correlation between high thermal stability and structural rigidity is investigated in detail. The white-light-emitting diode (W-LED) is assembled by depositing the obtained green-light-emitting phosphor Ca_3.99Y₃Si₇O₁₅N₅:0.01Eu²⁺ and commercial phosphors on a ultraviolet (UV)-emitting chip (λ = 365 nm). The CIE color coordinates, color rendering index (Ra), and corrected color temperature (CCT) of the obtained W-LED are (0.3724, 0.4156), 92.9, and 4806 K, respectively. In addition, when subjected to in situ high-pressure fluorescence spectroscopy, the phosphor exhibits an evident red shift of 40 nm with an increase in pressure from 0.2 to 32.1 GPa. The phosphor has the advantage of high-pressure sensitivity (dλ/dP = 1.13 nm GPa^-1) and visualization with pressure changes. The possible reasons and mechanisms are deeply discussed in detail. Based on the above advantages, Ca_3.99Y₃Si₇O₁₅N₅:0.01Eu²⁺ phosphor is expected to have potential applications in W-LEDs and optical pressure sensing.