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Microwave Absorption Enhancement of Multifunctional Composite Microspheres with Spinel Fe 3 O 4 Cores and Anatase TiO 2 Shells
Author(s) -
Liu Jiwei,
Che Renchao,
Chen Huajun,
Zhang Fan,
Xia Feng,
Wu Qingsong,
Wang Min
Publication year - 2012
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201102245
Subject(s) - materials science , anatase , reflection loss , superparamagnetism , crystallinity , transmission electron microscopy , spinel , chemical engineering , absorption (acoustics) , high resolution transmission electron microscopy , microwave , microstructure , dielectric loss , composite number , scanning electron microscope , nanoparticle , analytical chemistry (journal) , magnetization , nanotechnology , dielectric , photocatalysis , composite material , optoelectronics , metallurgy , biochemistry , chemistry , physics , quantum mechanics , magnetic field , engineering , catalysis , chromatography
Multifunctional composite microspheres with spinel Fe 3 O 4 cores and anatase TiO 2 shells (Fe 3 O 4 @TiO 2 ) are synthesized by combining a solvothermal reaction and calcination process. The size, morphology, microstructure, phase purity, and magnetic properties are characterized by scanning electron microscopy, transmission electron microscopy (TEM), high‐resolution TEM, selected‐area electron diffraction, electron energy loss spectroscopy, powder X‐ray diffraction, and superconducting quantum interference device magnetometry. The results show that the as‐synthesized microspheres have a unique morphology, uniform size, good crystallinity, favorable superparamagnetism, and high magnetization. By varying the experimental conditions such as Fe 3 O 4 size and concentration, microspheres with different core sizes and shell thickneses can be readily synthesized. Furthermore, the microwave absorption properties of these microspheres are investigated in terms of complex permittivity and permeability. By integration of the chemical composition and unique structure, the Fe 3 O 4 @TiO 2 microspheres possess lower reflection loss and a wider absorption frequency range than pure Fe 3 O 4 . Moreover, the electromagnetic data demonstrate that Fe 3 O 4 @TiO 2 microspheres with thicker TiO 2 shells exhibit significantly enhanced microwave absorption properties compared to those with thinner TiO 2 shells, which may result from effective complementarities between dielectric loss and magnetic loss. All the results indicate that these Fe 3 O 4 @TiO 2 microspheres may be attractive candidate materials for microwave absorption applications.