Luminescence degradation under moisture and thermal attacks during the term of service cannot be ignored for phosphors used in solid state lighting. In this work, the moisture-assisted thermal degradation of two commercially available red phosphors (Ca_1−xSr_x)AlSiN₃:Eu²⁺ with different Sr/Ca ratios (RP625: Sr/Ca = 0.9/0.1; RP660: Sr/Ca = 0/1) was investigated by treating phosphor powders at 170–230 °C for 8–96 h in pressurized water steam. The experimental results show that the chemical composition has a great impact on the thermal stability of (Ca_1−xSr_x)AlSiN₃:Eu²⁺, and a lower Sr/Ca ratio results in a smaller thermal degradation. The activation energies for thermal degradation are 66.26 and 72.13 kJ mol⁻¹ for RP625 and RP660, respectively. The phase transformation, microstructure evolutions, diffuse reflectance spectra, photoluminescence and cathodoluminescence spectra of samples before and after thermal treatment were discussed to reveal the thermal degradation mechanism. The serious degradation observed in RP625 is caused by the decomposition of the phosphor host and the oxidation of the Eu²⁺ dopant, which is closely related to the increased bond length of Sr/Ca/Eu–N chemical bonds.

中文翻译：

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用于高显色性白光LED 的红光（Ca ₁ - _x Sr _x）AlSiN ₃：Eu ²⁺荧光粉的成分依赖性热降解†

对于固态照明中使用的磷光体，在使用期限内水分和热侵蚀下的发光降解不容忽视。在这项工作中，两种具有不同Sr / Ca比（RP625：Sr / Ca = 0.9 / 0.1; RP660：Sr ）的市售红色磷光体（Ca _{1- x} Sr _x）AlSiN ₃：Eu ²⁺的水分辅助热降解/ Ca = 0/1）是通过在加压水蒸汽中于170–230°C的温度下将磷光体粉末处理8–96 h来研究的。实验结果表明，化学成分对（Ca _{1− x} Sr _x）AlSiN ₃：Eu ²⁺的热稳定性有很大影响。，而较低的Sr / Ca比值会导致较小的热降解。对于RP625和RP660，用于热降解的活化能分别为66.26和72.13kJ mol ^-1。讨论了样品在热处理前后的相变，显微组织演变，漫反射光谱，光致发光和阴极荧光光谱，揭示了热降解机理。在RP625中观察到的严重降解是由荧光体主体的分解和Eu ²⁺掺杂剂的氧化引起的，这与Sr / Ca / Eu-N化学键的键长增加密切相关。