Ultra‐Thin Oxide‐Based Double‐Layer Architecture Achieves Wide‐Temperature Broadband Microwave Absorption by Synergizing Lorentz Resonance and Thermionic Transport

Achieving high and stable permittivity is essential for developing ultra-thin and wide-temperature adaptive microwave-absorbing materials (MAMs). Conventional high-permittivity MAMs suffer from temperature-sensitive permittivity and cannot achieve stable microwave-absorbing performance at fluctuating temperatures, while temperature-insensitive MAMs exhibit low permittivity that severely restricts ultra-thin designs. Herein, a double-layer La₂Zr₂O₇/Eu₂Zr₂O₇ architecture is employed, with rare-earth zirconates featuring with one-eighth anion-site vacancies, as a promising candidate for ultra-thin wide-temperature adaptive MAMs. The established balance between thermionic relaxation polarization and Lorentz dielectric resonance-activated by oxygen ions-can largely increase the real part of permittivity of La₂Zr₂O₇ while maintaining its stability at different temperatures. Concurrently, strong thermionic transport induces an increase in dielectric loss capacity of Eu₂Zr₂O₇, which can broaden effective absorption bandwidth (EAB) effectively. Moreover, the macroscopic interfacial resonance between two layers overcomes the limitations imposed by the quarter-wavelength theory, generating new absorption peak for further expanding EAB. Under synergistic coupling of these mechanisms, it is successfully achieved superior EAB-completely covering the Ku band (12.4-18 GHz) over a wide-temperature range (400-800 °C) at an ultra-thin fixed thickness of just 1.2 mm, coupled with a maximum EAB/d of 3.6 GHz mm^-1. This innovative design offers promising pathways for developing ultra-thin and wide-temperature adaptive MAMs.