CoFe2O4-Co3Fe7纳米粒子及CoFe2O4/多孔碳的制备及其电磁性能研究

在5% H₂+95% N₂气氛下，还原CoFe₂O₄纳米粒子制备了CoFe₂O₄-Co₃Fe₇纳米粒子；以焙烧黄麻纤维得到的多孔碳纤维为碳源用水热法将CoFe₂O₄纳米粒子负载到多孔碳中，制备出CoFe₂O₄/多孔碳。使用X射线衍射仪、扫描电子显微镜、透射电子显微镜、拉曼光谱仪、同步热分析仪等手段对材料进行表征，并使用矢量网络分析仪测量了复合材料的电磁参数和微波吸收性能。结果表明，CoFe₂O₄-Co₃Fe₇纳米粒子和CoFe₂O₄/多孔碳的微波吸收性能明显优于CoFe₂O₄纳米粒子。CoFe₂O₄-Co₃Fe₇纳米粒子的有效频宽(反射损耗<-10 dB的频率宽度)可达4.8 GHz。CoFe₂O₄/多孔碳的有效频宽可达6 GHz，覆盖了整个Ku波段(12~18 GHz)。这些材料优异的微波吸收性能，可归因于合适的介电常数、大的介电损耗、多孔结构以及介电损耗和磁损耗的协同作用。

Preparation and Electromagnetic Properties of CoFe2O4-Co3Fe7 Nanoparticles and CoFe2O4/Porous Carbon

CoFe₂O₄-Co₃Fe₇ nanoparticles were successfully prepared by reducing CoFe₂O₄ nanoparticles in 5% H₂ + 95% N₂. Meanwhile, CoFe₂O₄ nanoparticles were successfully loaded onto the porous carbon by hydrothermal method with the porous carbon fiber calcined from jute fiber as precursor. The prepared two composites were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectrometer, and simultaneous thermal analyzer (STA). Their electromagnetic parameters and microwave absorption performances were measured by vector network analyzer (VNA). The results show that the microwave absorption performances of CoFe₂O₄-Co₃Fe₇ nanoparticles and CoFe₂O₄/porous carbon are obviously better than that of the plain CoFe₂O₄ nanoparticles. The effective bandwidth (frequency width of reflection loss <-10 dB) of CoFe₂O₄-Co₃Fe₇ nanoparticles is 4.8 GHz, while that of CoFe₂O₄/porous carbon can reach 6 GHz, covering the entire Ku band (12~18 GHz). The excellent microwave absorption performance can be attributed to the appropriate dielectric constant, large dielectric loss, porous structure, and the synergistic effect of dielectric loss and magnetic loss. Owing to the characteristics of low cost, low density and good microwave absorption performance, the CoFe₂O₄/porous carbon has broad application prospect for Ku band as an economic, lightweight and broadband microwave absorbent.