Effect of co-doping with calcium and transition metals on the infrared emissivity of La2(Zr0.7Ce0.3)2O7 ceramics for high-temperature thermal protection applications

The La-2(Zr0.7Ce0.3)(2)O-7 (LZ7C3) ceramics co-doped with Ca2+ and different transition metal cations (Fe3+, Cr3+) were fabricated by the pressureless-sintering method. The influence of doping on the phase structure, microstructure and infrared emissivity (0.75-2.5, 3-5, 8-14 mu m) was investigated. The infrared emissivity of LZ7C3 in the wavelength range 0.75-2.5 and 3-5 mu m was significantly enhanced by co-doping, especially with Ca2+ and Cr3+. The infrared emissivity in the wavelength range 0.75-2.5 mu m could be improved from 0.069 (LZ7C3) to 0.876 at room temperature, and from 0.463 (LZ7C3) to 0.877 in 3-5 mu m at 300 degrees C, by co-doping with Ca2+ and Cr3+. On the other hand, doping had an insignificant effect on the infrared emissivity of LZ7C3 in the 8-14 mu m range at 300 degrees C due to its high emissivity value (0.962) in the 8-14 mu m range. (C) 2020 The Ceramic Society of Japan. All rights reserved.