Highly efficient narrow-band red emitting (RE) phosphors are the most desired and requested materials for developing illumination grade phosphor-converted light emitting diodes (pcLEDs). This study presents direct measurements of RE energy levels, critical to the color and efficiency of LED phosphors. For the first time, we experimentally determine the energetic separation of the Eu 5d state and the conduction band, which is the key indicator of quantum efficiency. This was achieved for the next-generation pcLED phosphors Li₂Ca₂[Mg₂Si₂N₆]:Eu²⁺, Ba[Li₂(Al₂Si₂)N₆]:Eu²⁺, and Sr[LiAl₃N₄]:Eu²⁺ using resonant inelastic X-ray scattering. Band to band and 4f to valence band transitions are directly observed in X-ray excited optical luminescence spectra of Sr[LiAl₃N₄]:Eu²⁺ and Sr[Mg₃SiN₄]:Eu²⁺. These techniques are widely applicable and create a comprehensive, experimental picture of the Eu²⁺ energy levels in these compounds, leading to a complete understanding of all pertinent electronic processes. This study forms the base needed for a detailed discussion of the structure–property relationships, such as specific atoms, coordination and density of states, underpinning phosphor color and efficiency.

中文翻译：

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直接测量氮化物荧光粉的能级及其与热猝灭行为的关系

高效窄带红光发射（RE）磷光体是用于开发照明级磷光转换发光二极管（pcLED）的最需要和要求的材料。这项研究提出了对RE能量水平的直接测量，这对LED荧光粉的颜色和效率至关重要。首次，我们通过实验确定了Eu 5d态与导带的高能分离，这是量子效率的关键指标。这是通过下一代pcLED荧光粉Li ₂ Ca ₂ [Mg ₂ Si ₂ N ₆ ]：Eu 2 ⁺，Ba [Li ₂（Al ₂ Si ₂）N ₆ ]：Eu ^{2+实现的。}和Sr [LiAl ₃ N ₄ ]：Eu ^2+的共振非弹性X射线散射。在Sr [LiAl ₃ N ₄ ]：Eu ²⁺和Sr [Mg ₃ SiN ₄ ]：Eu ^2+的X射线激发光致发光光谱中直接观察到能带跃迁和4f到价带跃迁。这些技术被广泛应用，并创建了Eu ²⁺的综合实验图这些化合物的能级，从而使您对所有相关的电子过程有一个完整的了解。这项研究为详细讨论结构与性质之间的关系奠定了基础，例如特定原子，状态的配位和密度，荧光粉颜色和效率的基础。