Temperature-dependent infrared emissivity property of Ce-doped ZnO nanoparticles

Abstract The low infrared emissivity materials with good high-temperature properties remain a challenge for the infrared stealth of hot targets in 3–5 μm waveband. To further decrease the infrared emissivity of ZnO, the Ce-doped ZnO nanoparticles were prepared by a facile sol-gel method and the infrared emissivity properties in 3~5 μm waveband in high temperature conditions were deeply investigated by doping different concentration of Ce in ZnO. The influences of Ce dopant concentration on the microstructure, morphology, conductivity, lattice vibration and high-temperature infrared emissivity properties of Ce-doped ZnO were systematically studied, as well as the detailed analysis of temperature-dependent infrared emissivity properties through the conductivity and lattice vibration based on the theory of solid state physics. When the Ce dopant concentration is 3%, the infrared emissivity of Ce-doped ZnO decreases dramatically from room temperature to 800 °C in comparison with undoped ZnO and reaches the lowest value of 0.329 at 500 °C. It is indicated that the excess doping of Ce would produce an impurity phase of CeO2 in the crystal, therefore decreases the conductivity, and causes extra lattice vibration in infrared region, and results in the increase of infrared emissivity. The infrared emissivity versus temperature exhibits a “U” type curve, which is caused by the competition effects of the conductivity and lattice vibration at elevated temperature.