High-entropy rare earth stannate ceramics: Acid corrosion resistant radiative cooling materials with high atmospheric transparency window emissivity and high near-infrared solar reflectivity

In response to the development concept of "carbon neutrality" and "carbon peak", it is critical to develop materials with high near-infrared (NIR) solar reflectivity and high emissivity in atmospheric transparency window (ATW, 8-13 μm) to advance zero energy consumption radiative cooling technology. To achieve the regulation of emission and reflection properties, a series of high-entropy rare earth stannate ceramics (HE-RE₂Sn₂O₇: (Y_0.2La_0.2Nd_0.2Eu_0.2Gd_0.2)₂Sn₂O₇, (Y_0.2La_0.2Sm_0.2Eu_0.2Lu_0.2)₂Sn₂O₇, (Y_0.2La_0.2Gd_0.2Yb_0.2Lu_0.2)₂Sn₂O₇) with seriously lattice distortion were prepared using the solid phase reaction followed by pressureless sintering method for the first time. The lattice distortion is accomplished by introducing rare earth elements with different cation radius and masses. The as-synthesized HE-RE₂Sn₂O₇ 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^-1·K^-1) and excellent chemistry 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, through selecting excitation-difficult elements, HE-RE₂Sn₂O₇ with a wide band gap exhibits high NIR solar reflectivity. Hence, the multi-component design can effectively enhance the radiative cooling ability of HE-RE₂Sn₂O₇ and provide a novel strategy for developing radiative cooling materials.