低频雷达的快速发展对武器装备的隐身提出了更高的要求，中高频成熟的材料基本无法使用，国内尚存较多盲区，急需突破。一维羰基铁纤维具有高的各向异性和饱和磁化强度，低频磁导率高，但其介电频散无法匹配磁导率，难以满足阻抗匹配和低频宽带强吸收的需求。基于此，本申请项目着眼于500MHz-3GHz的低频需求，拟合成一维羰基铁/无机钙钛矿纤维，通过钙钛矿掺杂或取代调控其介电频散并匹配磁导率，实现低频区的宽波段、低厚度强吸收。本项目将借助同步辐射X射线吸收谱学，探索替换原子的近邻环境，弄清掺杂所导致的精细结构变化，同时结合正电子湮没谱所得缺陷信息，深入理解替换元素种类及含量变化时，其微观结构的变化及演化；结合理论计算阐明掺杂与介电频散、损耗、反射率之间的物理关联，为低频微波吸收材料的设计提供理论依据和技术支持。

The rapid development of low-frequency radar calls for improved low-frequency stealth behavior of weapons and equipment. Nevertheless, low frequency performance of traditional microwave absorbing materials cannot be compared with medium-high frequency performance, which inspires us to develop excellent low-frequency microwave absorbing materials. Due to the fact that one-dimensional carbonyl iron fibers possess strong anisotropy and high saturation magnetization, as well as high complex permeability in frequency range of 500 MHz-3 GHz, they have been considered as a promising candidate for low-frequency microwave absorbing materials. However, impedance mismatching of iron fibers caused by poor dielectric dispersion properties poses negative effect on the thin-thickness and broadband electromagnetic wave absorption. Thus, this project aims at the low frequency between 500 MHz and 3 GHz, which would be achieved by well-designed one-dimensional carbonyl iron/perovskite fibers. Through doping or replacement of perovskite, the dielectric dispersion performance of the composites fibers would be modified to match with changeable complex permeability, which contributes to the amelioration of low frequency behavior. With the help of advanced synchronous radiation technique, the physical and chemical environment of doped atoms as well as detailed structure change can be determined. The effect of type and amount of doping element on the evolutions of microstructure would be also ascertained by analyzing defect information from positron annihilation spectroscopy. Combining theoretical calculation, we are able to establish the structure-activity relationship of one-dimensional fibers between doping state and physical parameters including dielectric dispersion, attenuation and reflection loss performance, which would provide theoretical basis and technical support for designing low-frequency microwave absorbing material.