溶胶-凝胶法制备LAMO/Ni_2Z复合粉体的微波吸收特性

Microwave absorbing characteristics of LAMO/Ni_2Z composite powders prepared by sol-gel precursor method

采用溶胶-凝胶工艺首先制备La0.85Ag0.15MnO3和（Ba0.7Sr0.3）3Ni2Fe24O41的前驱体，经煅烧制得由钙钛矿结构的La0.85Ag0.15MnO3稀土锰氧化物和Z型六角铁氧体（Ba0.7Sr0.3）3Ni2Fe24O41组成的复合材料，利用X射线衍射仪和扫描电镜分别分析其微结构和形貌；使用矢量网络分析仪系统测量该复合材料的微波电磁参数和吸波性能，并对影响其微波吸收性能的主要因素及作用机理进行研究与分析。结果表明：1250℃的煅烧温度下， La0.85Ag0.15MnO3含量（质量分数）为40%的复合材料的微波吸收峰值达-30 dB，在2～18 GHz频段小于-10 dB的吸收频宽为3.9 GHz，微波吸收性能明显优于La0.85Ag0.15MnO3单相材料和Z型六角铁氧体（Ba0.7Sr0.3）3Ni2Fe24O41单相材料；复合材料中存在介电损耗和磁损耗共存与协同作用，以及界面效应和磁电耦合作用，有利于介电常数调控和阻抗匹配优化，从而提高微波吸收性能。

Composites of La0.85Ag0.15MnO3 with perovskite structure and Z-type ferrite （Ba0.7Sr0.3）3Ni2Fe24O41 were synthesized by the sol-gel precursor calcination method. Microstructure and morphology of the composites were analyzed by X-ray diffraction meter （XRD） and scanning electron microscope （SEM）. Electromagnetic parameters and microwave absorption of the composites were measured by the microwave vector network analyzer system. The main influencing factors and their function mechanism on microwave absorbing for the composites were also explored. The results show that, the microwave absorption peak value is-30 dB and the bandwidth below-10 dB reaches 3.9 GHz in 2-18 GHz frequency range for the composite with 40wt%La0.85Ag0.15MnO3 prepared by calcination temperature of 1 250℃, which is much better than those of the single phase materials. Because of coexistence of dielectric loss and magnetic loss, interfacial and magnetoelectric coupling effect for the composite, the permittivity can be regulated and controlled effectively and impedance matching as well as microwave absorption are improved.