Flame-spraying synthesis and infrared emission property of Ca2+/Cr3+ doped LaAlO3 microspheres

Ca2+/Cr3+ doped LaAlO3 microspheres were prepared by using a facile flame-spraying synthesis (FSS) technique. Phase composition and microstructure of the samples were characterized by XRD, EDS and SEM. The particle size of pure and doped LaAlO3 microspheres was 5-20 μm with a narrow size distribution. The effects of Ca2+/Cr3+ doping concentration and annealing temperature on infrared emissivity of doped LaAlO3 microspheres were investigated. It revealed that the infrared emissivity of LaAlO3 could be significantly enhanced by Ca2+-Cr3+ co-doping and it increased mainly with the content of Cr3+, reaching as high as 0.93. After heat-treatment at 900-1500 °C, the infrared emissivity of doped LaAlO3 microspheres was further improved. It indicates as-synthesized Ca2+-Cr3+ co-doped LaAlO3 microspheres are expected to be the next generation of infrared radiation agent for energy-saving applications, due to their high emissivity and melting point, and excellent chemical stability at high temperature.