标题: | Microwave-absorbing characteristics for the composites of thermal-plastic polyurethane (TPU)-bonded NiZn-ferrites prepared by combustion synthesis method |
作者: | Peng, CH Hwang, CC Wan, J Tsai, JS Chen, SY 材料科学与工程学系 Department of Materials Science and Engineering |
关键字: | NiZn ferrites;microwave absorbers;reflection loss;combustion synthesis |
公开日期: | 25-二月-2005 |
摘要: | NiZn ferrite with the chemical formula Ni0.5-xZn0.5-xM2xFe2O4 (M = Co, Cu, or Mg, and x = 0 or 0.05) was synthesized by a combustion synthesis method using metal nitrates and urea ((NH2)(2)CO) as reactants. The narrocrystallite of these materials were mixed with a thermal-plastic polyurethane (TPU) elastomer to be converted into a microwave-absorbing composite. The complex relative permittivity (epsilon(r) = epsilon'-jepsilon") and permeability (mu(r)=mu'-jmu") of the absorber were measured in a frequency range of 2-12GHz. The reflection loss (R.L.), matching frequency (f(m)) and matching thickness (d(m)) were calculated using the theory of the absorbing wall. Effects of both the particle size of ferrite and the dopant presented in the ferrite on the electromagnetic properties and microwave-absorbing characteristics were investigated. It was found that nanoparticles around 40 nm exhibit higher reflection loss than both those obtained from micro-sized powders and those with size less than 25 nm. Also, it was shown that the Co-doped, Mg-doped, and Cu-doped NiZn ferrite-TPU composites could be designed to be more negative than -20 dB, in a frequency range of 2-12 GHz, to become promising materials for microwave-absorbing application. These doped ferrite-containing composites have more effective microwave-absorbing characteristics compared to undoped one. (C) 2004 Elsevier B.V. All rights reserved. |
URI: | http://dx.doi.org/10.1016/j.mseb.2004.10.022 http://hdl.handle.net/11536/13996 |
ISSN: | 0921-5107 |
DOI: | 10.1016/j.mseb.2004.10.022 |
期刊: | MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY |
Volume: | 117 |
Issue: | 1 |
起始页: | 27 |
结束页: | 36 |
显示于类别: | Articles |
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