采用金属有机化学气相沉积(MOCVD)工艺, 以高纯Fe(CO)₅和SrFe₁₂O₁₉为原料, 高纯N₂为载气, 在SrFe₁₂O₁₉表面沉积连续Fe膜, 从而制得Fe-SrFe₁₂O₁₉复合材料. 用XRD, SEM, EDS和矢量网络分析仪对粉末的结构及电磁性能进行表征并对其吸波性能进行研究. 结果表明, SrFe₁₂O₁₉表面沉积的膜层为纯a-Fe相, 厚度约为0.5 mm, 沉积薄膜比较均匀完整地覆盖在SrFe₁₂O₁₉表面. SrFe₁₂O₁₉表面沉积a-Fe膜后, 其电磁性能发生明显改变, 吸波性能有较好改善. 沉积时间30 min时制备的样品有最佳的吸波效果, 涂层厚度为1.5~3.0 mm时, 最小反射率均低于-19 dB, 在6.8~18.0 GHz均能实现吸波强度低于-10 dB. 随着厚度的增加, 反射率峰值先减少后增加, 厚度为2.0 mm时, 达到最小值-21.2 dB.

Nowadays, more and more researchers pay attention to the microwave absorbing materials with the increase of electromagnetic pollution and the development of stealth technology for military platforms. Traditional microwave absorbers, such as ferrite, metal powder, conductive magnetic fibers, magnetic flake powder, and nanoparticles and so on, are facing some common problems such as large specific gravity, narrow absorption bandwidth, large match thickness and poor absorption performance. Composites with core-shell structures are becoming promising microwave absorbing material because such structure can exhibit magnetic and dielectric characteristics through the proper selection of core and shell materials. Thus, Fe(CO)₅ deposition on the SrFe₁₂O₁₉ surface has been considered for the fabrication of a new composite that possesses the advantages of these two materials. This new composite might also obtain remarkable microwave absorption through thin layer absorbers in the entire 2~18 GHz frequency range. The Fe-SrFe₁₂O₁₉ composites with core-shell structures were prepared by metal organic chemical vapor deposition (MOCVD) using the SrFe₁₂O₁₉ and iron pentacarbonyl [Fe(CO)₅] as the precursors. XRD, SEM, EDS and a vector network analyzer were used to characterize the structure and electromagnetic properties of the samples. The structure and morphology analyses show that the composites have complete core-shell structures with SrFe₁₂O₁₉ as core and Fe layers as shell. Fe nanoparticles were uniformly deposited on the surface of SrFe₁₂O₁₉ with thickness of about 0.5 mm at the reaction temperature of 180 ℃ with N₂ flow rate of 30 mL/min for 30 min. Simulation studies show that SrFe₁₂O₁₉ electromagnetic properties changed significantly and the absorbing properties got evidently improvement after Fe deposited on its surface. The samples prepared with deposition time of 30 min have the best absorbing properties. A reflection loss (RL) value exceeding -10 dB in the range of 6.8~18.0 GHz frequency was obtained by selecting an appropriate thickness of the absorber layer from 1.5 to 3.0 mm. Moreover, a minimum RL of -21.2 dB at was obtained for a 2.0 mm thick layer. Fe-deposited SrFe₁₂O₁₉ by MOCVD can significantly improve the electromagnetic properties of SrFe₁₂O₁₉ and Fe-SrFe₁₂O₁₉ composites could be used as an effective microwave absorption material.