title: Study on preparation and microwave absorption property of the core-nanoshell composite materials doped with La.
abstract: Microwave absorbing material plays a great role in electromagnetic pollution controlling, electromagnetic interference shielding and stealth technology, etc. The core-nanoshell composite materials doped with La were prepared by a solid-state reaction method, which is applied to the electromagnetic wave absorption. The core is magnetic fly-ash hollow cenosphere, and the shell is the nanosized ferrite doped with La. The thermal decomposition process of the sample was investigated by thermogravimetry and differential thermal analysis. The morphology and components of the composite materials were investigated by the X-ray diffraction analysis, the microstructure was observed by scanning electron microscope and transmission electron microscope. The results of vibrating sample magnetometer analysis indicated that the exchange-coupling interaction happens between ferrite of magnetic fly-ash hollow cenosphere and nanosized ferrite coating, which caused outstanding magnetic properties. The microwave absorbing property of the sample was measured by reflectivity far field radar cross section of radar microwave absorbing material with vector network analyzer. The results indicated that the exchange-coupling interaction enhanced magnetic loss of composite materials. Therefore, in the frequency of 5 GHz, the reflection coefficient can achieve -24 dB. It is better than single material and is consistent with requirements of the microwave absorbing material at the low-frequency absorption.
authors: College of Environmental and Chemical Engineering, Dalian Jiaotong University, Dalian 116028, China.
authors: Liqiu
authors: L
authors: Wei
authors: College of Environmental and Chemical Engineering, Dalian Jiaotong University, Dalian 116028, China. Electronic address: mailjyl@yahoo.com.cn.
authors: Ruxin
authors: R
authors: Che
authors: School of Physics, Peking University, Beijing 100871, China.
authors: Yijun
authors: Y
authors: Jiang
authors: College of Environmental and Chemical Engineering, Dalian Jiaotong University, Dalian 116028, China.
authors: Bing
authors: B
authors: Yu
mesh_terms: D065966:Absorption, Physicochemical; D060729:Coal Ash / Q000737:chemistry; D004055:Differential Thermal Analysis; D007811:Lanthanum / Q000737:chemistry; D060328:Magnetic Phenomena; D008872:Microwaves; D057145:Nanoshells / Q000737:chemistry / Q000648:ultrastructure; D013052:Spectrometry, X-Ray Emission; D013818:Thermogravimetry; D014961:X-Ray Diffraction
chemical_list: D060729:Coal Ash; D007811:Lanthanum
keywords: La; core-nanoshell composite materials; magnetic fly-ash hollow cenosphere; magnetic properties