Materials that can provide reliable electromagnetic interference (EMI) shielding in highly oxidative atmosphere at elevated temperature are indispensable in the fast-developing aerospace field. However, most of conductor-type EMI shielding materials such as metals can hardly withstand the high-temperature oxidation, while the conventional dielectric-type materials cannot offer sufficient shielding efficiency in gigahertz (GHz) frequencies. Here, a highly deficient medium-entropy (ME) perovskite ceramic as an efficient EMI shielding material in harsh environment, is demonstrated. The synergistic effect of entropy stabilization and aliovalent substitution on A-site generate abnormally high concentration of Ti and O vacancies that are stable under high-temperature oxidation. Due to the clustering of vacancies, the highly deficient perovskite ceramic exhibits giant complex permittivity and polarization loss in GHz, leading to the specific EMI shielding effectiveness above 30 dB/mm in X-band even after 100 h of annealing at 1000 °C in air. Along with the low thermal conductivity, the aliovalent ME perovskite can serve as a bifunctional shielding material for applications in aircraft engines and reusable rockets.

中文翻译：

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一种用于恶劣环境下电磁干扰屏蔽的高缺陷中熵钙钛矿陶瓷

在快速发展的航空航天领域中，能够在高温高氧化气氛中提供可靠的电磁干扰（EMI）屏蔽的材料是不可或缺的。然而，大多数金属等导体型EMI屏蔽材料难以承受高温氧化，而传统的介电型材料在千兆赫（GHz）频率下无法提供足够的屏蔽效率。在这里，展示了一种高度缺乏的中熵（ME）钙钛矿陶瓷作为恶劣环境下的高效 EMI 屏蔽材料。熵稳定和A位异价取代的协同作用产生异常高浓度的Ti和O空位，这些空位在高温氧化下保持稳定。由于空位的聚集，高度缺陷的钙钛矿陶瓷在GHz范围内表现出巨大的复介电常数和极化损耗，导致即使在空气中1000℃退火100小时后，X波段的比EMI屏蔽效能仍高于30dB/mm 。除了低导热率之外，异价 ME 钙钛矿还可以作为双功能屏蔽材料，应用于飞机发动机和可重复使用的火箭。