【作者】 李俊；

【导师】 冯双久； 王银海；

【作者基本信息】 安徽大学 ， 材料学， 2006， 硕士

【摘要】 吸波材料是一种重要的军事隐身功能材料，其机理本质上是电磁波与物质相互作用，入射的电磁波通过介质最大限度地转变成热能或其他形式的能。本论文分为四章从理论和实验上研究了Bi系层状铜氧化物的微波吸收性质 第一章综述了目前国内外吸波材料的研究动态，讨论了吸波材料的种类、性能特点、合成方法、吸波机理等，并对如铁氧体吸波材料、碳纤维结构吸波材料、纳米吸波材料、手性吸波材料、多晶铁纤维吸波材料、导电高聚物吸波材料等的研究进展作了概要介绍。 第二章从Bi系层状铜氧化物材料的结构出发，针对它沿c轴方向形成纳米级的导电层与介电层周期堆垛结构的特点，提出Bi系层状铜氧化物晶粒可以等效为一个LC振荡回路，并计算了它的振荡频率，发现振荡频率除了与材料的晶格参数和物理参量有关外，只与材料晶粒ab面的截面积有关。带入相关数据计算，发现晶粒的振荡频率在微波频段，表明从理论上证明此类材料可以作为微波吸收剂使用。并且提出通过控制晶粒尺寸可以调控中心吸收频率，通过控制晶粒尺寸分布来展宽吸收频带。 第三章主要研究了材料中导电层厚度对吸波性质的影响，通过对具有不同导电层厚度的Bi₂Sr₂CuO_y和Bi₂Sr₂CaCu₂O_y微波吸收性能的比较发现，似乎导电层越厚，微波吸收性能越好。但进一步研究发现，Bi₂Sr₂CaCu₂O_y的吸波性能优于Bi₂Sr₂CuO_y的原因可能是材料中晶粒取向的差异造成的。对不同厚度的涂层性质研究发现，此类材料的吸波性能对涂层厚度不是很敏感。 第四章研究了导电层与介电层电阻率对材料吸波性质的影响。研究了不同含量Y掺杂Bi₂Sr₂CaCu₂O_y的微波吸收性质，发现Y掺杂虽然可以明显增大材料中导电层和介电层的电阻率，但掺杂对材料微波吸收性能几乎没有影响，这表明材料的微波吸收性能与导电层的涡流损耗和介电层的介电损耗都没有明显的关联效应。考虑到材料中的载流子是限制在纳米尺度的导电层内运动，可能会类似纳米更多还原

【Abstract】 The electromagnetic wave absorbing materials were an important functional materials used in military stealth technology, in the materials the most incident electromagnetic wave energy was transferred to the heat or other form of energy due to the interaction between the electromagnetic wave and crystal lattice and electrons in the materials. It was presented in four chapters in this thesis to discuss the microwave absorbing properties of Bi-based layered cuprates.In chapter one, a survey on the development of electromagnetic wave absorbing materials in native and abroad was given. The classification of the absorbing materials, the materials properties, the synthetic method of the materials and the absorbing mechanism of the materials ere discussed. The development in ferrites absorbing materials, metallic fibers absorbing materials, nanometer size absorbing materials, chiral absorbing and material conductive polymer absorbing materials were introduced.In chapter two, based on the structure of periodic compile of nanometer conductor layer and dielectric layer in c axis in Bi-based cuprates, it is proposed that the planet crystal particle can be treated as a LC resonance loop. The resonance frequency of the LC loop is calculated and it is found that the frequency only dependent on the area in ab plane of the crystal particle besides the crystal lattice parameter and the dielectric constant of the materials. It was found that the frequency in the microwave band when the correlated parameter of material was introduced, which was indicated that the Bi-based cuprates can be used as microwave absorber. The absorbing centre frequency can be controlled by the particle size of the materials and the absorbing bandwidth can be controlled by the configuration of the particle size.The influence of the conducting layer thickness on the microwave absorbing更多还原