MnO_(2)纳米棒的吸波性能及其超构表面设计

Absorbing property of MnO_(2) nanorods and its meta-surface design

采用水热法和冷冻干燥技术制备MnO_(2)纳米棒材料,并利用模压法制备不同填充浓度的MnO_(2)/石蜡环状样品。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)、矢量网络分析仪(VNA)对样品的物相、微观结构、电磁参数进行了表征与测试,利用CST软件模拟设计了样品材料的超构表面,并对其设计前后的电磁波反射率进行了模拟计算与研究。结果表明:制备的MnO_(2)粉体呈棒状结构,棒体直径约50-100 nm,长度约5-10μm,单根结构圆柱度高,整体的结构均一性和结晶度好;MnO_(2)/石蜡样品的电磁衰减系数(α)随MnO_(2)纳米棒填充浓度的提高而增大,主要得益于随浓度增加而逐渐提升的介电损耗正切值(tanδ);超构表面的设计极大地拓宽了MnO_(2)/石蜡材料的微波吸收频域,2-18 GHz内最优频宽可达14.32 GHz,主要是超构表面引起的多谐振共存使得在规定频率范围内出现了多个吸收峰叠加而实现的。

MnO_(2) nanorods were prepared by using the hydrothermal method and freeze-drying technology,and then molded into the MnO_(2)/paraffin circular samples in different filling concentrations.The crystalline phase,microstructure and electromagnetic parameters of the samples were characterized and tested by X-ray diffractometer(XRD),scanning electron microscopy(SEM),and vector network analyzer(VNA).Sample meta-surface was designed and simulated by CST software and the pre and post simulation calculation and research of the meta-surface were carried out.The results show that prepared MnO_(2) powder has a rod structure with the diameter and length of the rod about 50-100 nm,5-10μm,respectively.The single cylindric structure is well-shaped,and the overall structure is homogeneous with crystallinity.Moreover,the tangent of dielectric loss(tanδ)increases with concentration,making a great contribution to the electromagnetic attenuation coefficient(α)of the sample of MnO_(2)/paraffin,which increases with filling concentration of MnO_(2) nanorods.Microwave absorption frequency domain of MnO_(2)/paraffin material is significantly broadened by the design of meta-surface,namely,the optimal bandwidth in 2-18 GHz can reach 14.32 GHz.The reason is the superposition of absorption peaks over a specified frequency range,which is caused by the coexistence of multiple resonances of the meta-surface.