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

## TL;DR

A new ultra-thin material design achieves stable microwave absorption across a wide temperature range using a double-layer structure.

## Contribution

A double-layer La2Zr2O7/Eu2Zr2O7 architecture enables ultra-thin, wide-temperature microwave absorption via synergistic polarization and resonance mechanisms.

## Key findings

- The double-layer structure achieves stable permittivity and broadband microwave absorption from 12.4–18 GHz at 1.2 mm thickness.
- The material maintains performance across a wide temperature range (400–800°C) due to thermionic transport and Lorentz resonance.
- The design overcomes limitations of traditional quarter-wavelength theory by introducing macroscopic interfacial resonance.

## Abstract

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.

Developing ultrathin wide‐temperature adaptive microwave absorption materials (MAMs) is crucial for enhancing the survival of military devices under alternating high‐temperature environment. Here, a double‐layer La2Zr2O7/Eu2Zr2O7 architecture is employed, with rare‐earth zirconates featuring with one‐eighth anion‐site vacancies, successfully achieving broadband and stable microwave‐absorbing performance over a wide‐temperature range (400–800 °C) at an ultra‐thin fixed thickness of merely 1.2 mm. This innovative design offers a promising pathway for developing ultra‐thin and wide‐temperature adaptive MAMs.