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Magnetic and Impedance Properties of Nanocomposite CoFe 2 O 4 / Co 0.7 Fe 0.3 and Single‐Phase CoFe 2 O 4 Prepared Via a One‐Step Hydrothermal Synthesis
Author(s) -
Zan Fenlian,
Ma Yongqing,
Ma Qian,
Xu Yuanfeng,
Dai Zhenxiang,
Zheng Ganhong,
Wu Mingzai,
Li Guang
Publication year - 2013
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.12437
Subject(s) - coercivity , remanence , magnetocrystalline anisotropy , nanocrystalline material , materials science , nanocomposite , analytical chemistry (journal) , magnetic anisotropy , phase (matter) , saturation (graph theory) , anisotropy , magnetization , nuclear magnetic resonance , chemistry , nanotechnology , chromatography , magnetic field , condensed matter physics , physics , organic chemistry , mathematics , quantum mechanics , combinatorics
Using a one‐step hydrothermal method and at different stirring speeds ( V s ), we have synthesized different types of CoFe 2 O 4 ‐based magnetic nanocrystalline samples. With increasing V s , the sample changes from a nanocomposite of CoFe 2 O 4 / Co 0.7 Fe 0.3 ( CFO / CF ) to single‐phase CoFe 2 O 4 ( CFO ). The maximum magnetization, 88.9 emu/g, and coercivity, 3010 Oe, were obtained when V s = 0. As V s increases, the saturation magnetization M s decreases, because the amount of soft magnetic CF phase decreases. A clear enhancement in the remanence, M r , was observed, with the maximum M r / M s = 0.67; the coercivity H c also exhibits a local maximum for the sample with V s = 200 r/min. These trends can be explained well by the interplay between dipolar interaction, magnetocrystalline anisotropy, and shape anisotropy. The stirring speed also influences the impedance of the materials; the related mechanism is discussed.