High-entropy rare earth stannate ceramics: Acid corrosion resistant radiative cooling materials with high atmospheric transparency window emissivity and high near-infrared solar reflectivity
Tao Chen, Yanyan He, Yanyu Pan, Kaixian Wang, Minzhong Huang, Liyan Xue, Yazhu Li, Fan Yang, Yanchun Zhou, Heng Chen
Abstract
In response to the development of the concepts of “carbon neutrality” and “carbon peak”, it is critical to developing materials with high near-infrared (NIR) solar reflectivity and high emissivity in the atmospheric transparency window (ATW; 8–13 μm) to advance zero energy consumption radiative cooling technology. To regulate emission and reflection properties, a series of high-entropy rare earth stannate ceramics (HE-RE<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub>: (Y<sub>0.2</sub>La<sub>0.2</sub>Nd<sub>0.2</sub>Eu<sub>0.2</sub>Gd<sub>0.2</sub>)<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub>, (Y<sub>0.2</sub>La<sub>0.2</sub>Sm<sub>0.2</sub>Eu<sub>0.2</sub>Lu<sub>0.2</sub>)<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub>, and (Y<sub>0.2</sub>La<sub>0.2</sub>Gd<sub>0.2</sub>Yb<sub>0.2</sub>Lu<sub>0.2</sub>)<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub>) with severe lattice distortion were prepared using a solid phase reaction followed by a pressureless sintering method for the first time. Lattice distortion is accomplished by introducing rare earth elements with different cation radii and mass. The as-synthesized HE-RE<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub> ceramics possess high ATW emissivity (91.38%–95.41%), high NIR solar reflectivity (92.74%–97.62%), low thermal conductivity (1.080–1.619 W·m<sup>−1</sup>·K<sup>−1</sup>), and excellent chemical stability. On the one hand, the lattice distortion intensifies the asymmetry of the structural unit to cause a notable alteration in the electric dipole moment, ultimately enlarging the ATW emissivity. On the other hand, by selecting difficult excitation elements, HE-RE<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub>, which has a wide band gap (<i>E</i><sub>g</sub>), exhibits high NIR solar reflectivity. Hence, the multi-component design can effectively enhance radiative cooling ability of HE-RE<sub>2</sub>Sn<sub>2</sub>O<sub>7</sub> and provide a novel strategy for developing radiative cooling materials.