High-Strength Micron-Thick Layered Ceramics with Ultralow Radiation Transmittance for Thermal Shielding Above 1273 K

Porous rare-earth oxide films are promising for thermal insulation but suffer from high heat-ray transparency and limited mechanical stability at extreme high-temperatures. Here, an alternately stacked Y₃NbO₇/GdTaO₄ ceramic film is presented for thermal insulation above 1273 K by effectively scattering both phonons and photons. This layered ceramic film has a low thermal conductivity of 0.35 W m⁻¹ K⁻¹ and a minimized near-infrared transmissivity of 0.5% at a thickness of 500 µm. Broadband photon backscattering (0.5–10 µm) is enabled by the hierarchical pores (1 and 5 µm), effectively suppressing radiative heat transfer while disrupting solid-phase heat conduction. Heterogeneous interfaces further enhance phonon scattering due to mismatched local lattice vibrations. Additionally, atomic interdiffusion and ferroelastic domain alignment at pore-free interfaces significantly improve bending strength tenfold to that of the state-of-the-art fiber-based aerogels with comparable thermal conductivity. These findings provide a design strategy for high-temperature protection material with high phonon/photon shielding and mechanical robustness.