New Insight for Luminescence Tuning Based on Interstitial sites Occupation of Eu²⁺ in Sr₃Al_2−xSi_xO_5−xN_xCl₂ (x = 0–0.4)

Abstract Currently, nitridation of phosphors provides an enormous inspiration for phosphor designing. In this paper, a nitridation process by means of substituting Al³⁺O²⁻ with Si⁴⁺N³⁻ in initial Sr₃Al₂O₅Cl₂:Eu²⁺ system is implemented. The phase purity is confirmed by X‐ray diffraction. The corresponding photoluminescence properties are recorded and analyzed by the excitation and emission spectra. Interestingly, new blue emission bands emerge in the range of 400–500 nm and the intensity increases with the increasing of substitution concentration. It is verified that the new emission band is derived from the residence of Eu²⁺ ions in the interstitial sites. The crystal structure refinement, transmission electron microscopy, and solid‐state nuclear magnetic resonance spectroscopy are exploited to analyze the color‐tunable luminescence mechanisms induced by the structural variation. Moreover, the thermal stability is characterized by the temperature‐dependent spectra. Attributed to the enhancement of lattice rigidity, the serious thermal quenching behavior is improved. Finally, the electroluminescence performance is measured for the fabricated white light‐emitting diodes (LEDs). By combining 370 nm ultraviolet LED chips, CaAlSiN₃:Eu²⁺ and Sr₃Al₂O₅Cl₂:Eu²⁺ phosphors, an ideal warm‐white emitting LED is successfully fabricated with the color rendering index = 92, color temperature = 3476 K, and color coordinate x = 0.37, y = 0.34.