期刊
JOURNAL OF PHYSICS D-APPLIED PHYSICS
卷 47, 期 27, 页码 -出版社
IOP PUBLISHING LTD
DOI: 10.1088/0022-3727/47/27/275001
关键词
hollow hemispheres; microwave absorption; interfacial polarization relaxation; Kittel natural resonance; XPS
资金
- 211 Project of Anhui University
- National Natural Science Foundation of China [51272002]
- Anhui Provincial Natural Science Foundation [1208085ME87]
- Technology Foundation for Selected Overseas Chinese Scholars, Ministry of Personnel of China [[2013]-385]
Bowl-like Fe3O4 hemispheres with a hollow structure have been synthesized with an average outer diameter of 250 nm and a shell thickness of 80 nm using tiny similar to 25 nm Fe3O4 nanoparticles. The complex permittivity, complex permeability and reflection loss of the samples in weight percentages of 60% of the hollow Fe3O4 hemispheres were studied by using an Agilent E5071 C vector network analyzer in the frequency range of 2-18 GHz. Results show that as-prepared samples exhibit improved microwave absorbing properties compared with our previously reported ball-like Fe3O4 microspheres and Fe3O4 hemispheres/r-GO composites. Two Cole-Cole semicircles reveal that there are dual dielectric relaxation losses: one is interfacial polarization relaxation, the other is dipolar relaxation. X-ray photoelectron and Fourier transform infrared spectra of the products calcinated at different temperatures reveal the enhanced interfacial polarization relaxation effect due to the higher concentration of Fe2+ ions in the surface layer and increased interfaces among the Fe3O4 nanoparticles that form the submicron-sized hollow Fe3O4 hemispheres. In addition, the fitted results of complex permeability demonstrate that the magnetic loss is mainly caused by the Kittel natural resonance.
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