Effects of Ca²⁺-Sr²⁺ doping on the infrared emissivity of LaCrO₃

LaCrO₃ shows excellent thermal stability and good emissivity, and can be used as a potential thermal protection material for hypersonic vehicle. In this study, LaCrO₃ and Ca²⁺-Sr²⁺ doped LaCrO₃ were prepared by solid state reaction at 1400 °C for 2 h. The microstructures of the samples and effects of Ca²⁺-Sr²⁺ doping on the infrared emissivity of LaCrO₃ were studied by XRD, XPS, FT-IR, and UV–VIS–NIR spectrophotometer. The results show that after doping Ca²⁺ and Sr²⁺ ions, the infrared emissivity of all samples has significantly improved at 2.5–10 μm, from 0.61 (minimum value) to above 0.90. In the range of 10–14 μm, the emissivity of pure LaCrO₃ and La_0.8Ca_xSr_0.2-xCrO₃ samples shows a similar trend and all remains above 0.97. Therefore, doping Ca²⁺ and Sr²⁺ can significantly increase the emissivity of LaCrO₃ at 2.5–10 μm, which makes it have a wider application prospect in the field of high temperature thermal protection.