title: Exchange coupling controlled ferrite with dual magnetic resonance and broad frequency bandwidth in microwave absorption.
abstract: Ti-doped barium ferrite powders BaFe12-xTixO19(x= 0, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 and 0.8) were synthesized by the sol-gel method. The phase structure and morphology were analyzed by x-ray diffraction (XRD) and scanning electron microscopy, respectively. The powders were also studied for their magnetic properties and microwave absorption. Results show that the Ti-doped barium ferrites (BFTO) exist in single phase and exhibit hexagonal plate-like structure. The anisotropy fieldHaof the BFTO decreases almost linearly with the increase in Ti concentration, which leads to a shift of the natural resonance peak toward low frequency. Two natural resonance peaks appear, which can be assigned to the double values of the Landé factorgthat are found to be ∼2.0 and ∼2.3 in the system and can be essentially attributed to the existence of Fe3+ions and the exchange coupling effect between Fe3+and Fe2+ions, respectively. Such a dual resonance effect contributes a broad magnetic loss peak and thus a high attenuation constant, and leads to a dual reflection loss (RL) peak over the frequency range between 26.5 and 40 GHz. The high attenuation constants are between 350 and 500 at peak position. The optimal RL reaches around -45 dB and the practicable frequency bandwidth is beyond 11 GHz. This suggests that the BFTO powders could be used as microwave absorbing materials with extraordinary properties.
authors.affiliation: State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
authors.forename: Jingguo
authors.initials: J
authors.lastname: Jia
authors.affiliation: State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
authors.forename: Chuyang
authors.initials: C
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
authors.forename: Ning
authors.initials: N
authors.lastname: Ma
authors.affiliation: State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
authors.forename: Gaorong
authors.initials: G
authors.lastname: Han
authors.affiliation: State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
authors.forename: Wenjian
authors.initials: W
authors.lastname: Weng
authors.affiliation: State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China.
authors.forename: Piyi
authors.initials: P
authors.lastname: Du
keywords: Ti-doped barium ferrite; broad bandwidth; dual absorption peaks; exchange coupling; natural resonance