Research On Microwave Absorbing Properties Of Bi-based Layered Cuprates

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...