Tunable shell thickness of Fe-N@SiO2 nanoparticles for strong and stable microwave absorption properties with enhanced oxidation resistance
Tunable shell thickness of Fe-N@SiO2 nanoparticles for strong and stable microwave absorption properties with enhanced oxidation resistance
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DOI：
10.1016/j.jallcom.2022.166015
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发表时间：
2022
影响因子：
6.2
通讯作者：
Yun Ling
中科院分区：
文献类型：
--
作者：
Sheng Ouyang;Honghong Fu;Yu Xie;Wen He;Yun Ling
Core-shell composites Fe-N@SiO 2 with 500 nm average sizes of cores have been successfully prepared by a combination of hydrothermal, gaseous nitriding and Stöber methods. The Fe-N cores are composed of Fe 4 N as major phase and FeN as minority. The thickness of SiO 2 shell increases continuously with increase of the tetraethyl orthosilicate weight. Relative to the natures of Fe-N, Fe-N@SiO 2 composites show slightly weaker ferromagnetic capacity, but much higher oxidation resistance. The Fe-N sample exhibits extremely high relative permittivity. With filling loading of 50 wt%, it has a moderate microwave absorption performance with a maximum reflection loss about –10 dB. Owing to low conductivity, non-magnetic property and superior anti-oxidation ability of the SiO 2 shell, the core-shell structures have considerably degraded permittivity, and nearly unchanged permeability. These changes bring a much better impedance matching between the permittivity and permeability, and further bring a greatly enhanced microwave absorption performance. All of the Fe-N@SiO 2 composites have strong absorption abilities. They are quite stable with variation of shell thickness. The composite of 52 nm shell thickness has maximum reflection loss of –23.1 dB at 17.2 GHz, and effective absorption bandwidth (< –10 dB) of 2.4 GHz with absorber thickness 5.5 mm. The present study gives an insight on the roles of silica material influencing the iron-based absorber’s absorption ability. • Fe-N@SiO 2 nanoparticles with tunable shell thickness were synthesized • Ferromagnetic Fe-N@SiO 2 composites have good oxidation resistance • Core-shell absorbers exhibit strong and stable absorption performance • Mechanism for SiO 2 modification of absorption performance was revealed
