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In situ synthesis of hierarchical rose-like porous Fe@C with enhanced electromagnetic wave absorption†
Journal of Materials Chemistry C ( IF 5.7 ) Pub Date : 2017-12-13 00:00:00 , DOI: 10.1039/c7tc04897a
Xueai Li 1, 2, 3, 4 , Daxue Du 1, 2, 3, 4 , Chunsheng Wang 2, 3, 4, 5, 6 , Haiyan Wang 1, 2, 3, 4 , Zhaopeng Xu 2, 3, 4, 6, 7
Affiliation  

To satisfy the requirements of high-performance electromagnetic wave absorbers, composites of carbon and ferromagnetic metal with designed morphologies and abundant interfaces are highly desirable to balance impedance matching and attenuation. However, the synthesis of composites to meet these requirements and analysis of the electromagnetic wave energy loss mechanism remain great challenges. In this study, hierarchical rose-like assemblies of carbon–wrapped iron (Fe@C) nanoparticles with a porous structure were successfully synthesized via an in situ route using an iron alkoxide precursor with a rose-like morphology. Under the studied pyrolysis atmosphere and temperature, rose-like Fe@C and pure iron can be well modulated. The carbon shell is graphitic and highly ordered due to the catalytic effects of the iron nanoparticles, which affect the electromagnetic properties of the composites. The electromagnetic wave absorption properties of the Fe@C composite and iron are estimated in the frequency range of 2.0–18.0 GHz, and as expected, the hierarchical rose-like porous Fe@C demonstrates outstanding reflection loss characteristics with a minimum value of −71.47 dB with a thin matched thickness of 1.48 mm. Moreover, an ultra-wide response bandwidth (reflection loss of less than −10 dB) of 2.88–18.0 GHz is achieved. Analysis of the electromagnetic properties revealed that the hierarchical rose-like Fe@C presents very different electromagnetic functions in comparison to pure iron and Fe@C particles without the rose-like structure derived from the iron alkoxide precursor with the same structure. The carbon shells and special morphology with a certain microstructure can effectively regulate the complex permittivity and permeability to modify the impedance matching characteristic as well as enhance the attenuation ability via electromagnetic wave multiple reflection and scattering in the hierarchical rose-like Fe@C particles. Analysis of the attenuation constant and matched characteristic impedance validates that the enhanced electromagnetic wave absorption of the rose-like Fe@C with a porous structure is due to the significant enhancement of matched impedance and collective multiple loss mechanism.

中文翻译:

电磁波吸收增强的分层玫瑰状多孔Fe @ C的原位合成

为了满足高性能电磁波吸收器的要求,迫切需要具有设计形态和丰富界面的碳和铁磁金属复合材料,以平衡阻抗匹配和衰减。然而,满足这些要求的复合材料的合成以及电磁波能量损失机理的分析仍然是巨大的挑战。在这项研究中,具有多孔结构的分层玫瑰状碳包裹的铁的组件(FE @ C)纳米颗粒成功地合成通过一个原位路线使用具有玫瑰状形态的烷氧基铁前体。在所研究的热解气氛和温度下,玫瑰状的Fe @ C和纯铁可以得到很好的调制。由于铁纳米颗粒的催化作用,碳壳是石墨的并且高度有序,这影响了复合材料的电磁性能。估计Fe @ C复合材料和铁的电磁波吸收特性在2.0-18.0 GHz的频率范围内,并且正如预期的那样,分层的玫瑰状多孔Fe @ C表现出出色的反射损耗特性,最小值为-71.47。分贝,匹配厚度为1.48毫米。此外,获得了2.88–18.0 GHz的超宽响应带宽(反射损耗小于-10 dB)。电磁性能分析表明,与不具有玫瑰结构的纯铁和Fe @ C颗粒相比,分层的玫瑰状Fe @ C呈现出非常不同的电磁功能,而玫瑰状结构并非来自具有相同结构的烷氧基铁前驱体。具有一定微观结构的碳壳和特殊形态可以有效地调节复介电常数和磁导率,从而改变阻抗匹配特性,增强衰减能力。通过电磁波在玫瑰状Fe @ C分层粒子中进行多次反射和散射。对衰减常数和匹配的特征阻抗的分析证实,具有多孔结构的玫瑰状Fe @ C的增强的电磁波吸收归因于匹配阻抗和集体多重损失机制的显着增强。
更新日期:2017-12-13
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