Structural, physical, and magnetic analyses of Co-substituted BaFe 2 W-type hexaferrites prepared via the solid-state re
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Structural, physical, and magnetic analyses of Co‑substituted BaFe2 W‑type hexaferrites prepared via the solid‑state reaction Jin Tang1 · Dan Li2 · Hao He1 · Yimin Li1 · Jishu Zeng1 · Chen Liu1 Received: 22 November 2019 / Accepted: 21 February 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract BaCoxFe2−x W-type hexagonal ferrites with nominal composition BaCox Fe2+ Fe3+ O (x = 0.0, 0.5, 1.0, 1.5) were prepared by 2−x 16 27 conventional solid-state reaction in nitrogen at high annealing temperature of 1350 °C. X-ray diffraction and scanning electron microscopy were used to find out the structural and physical properties of BaCoxFe2−x W-type hexaferrites. Vibrating-sample magnetometry was used to measure hysteresis (M vs. H) loops. Furthermore, magneto-crystalline anisotropy constant (K), Bohr magneton (nB), initial permeability (μi), and magnetic anisotropy fields (Ha) of Co in BaCoxFe2−x W-type hexaferrites were also calculated. Finally, the magnetic characteristics of magnets were also analyzed by B–H measuring equipment. Keywords W-type hexaferrites · X-ray diffraction (XRD) · Scanning electron microscopy (SEM) · Microstructure · Magnetic properties
1 Introduction W-type ferrite is a member of the ferrite family with hexagonal crystal structure. It was first reported as the mixed phase of M-type and X-type hexagonal ferrite in 1952 [1]. The general chemical formula of W-type ferrite is Sr(Ba) Me2Fe16O27, Sr or Ba can be replaced by elements with similar radii, and Me is usually a divalent metal cation, such as Fe2+, Co2+, Ni2+, and Cu2+. In 1980, Lotgering et al. [2] reported that the saturation magnetization (Ms) value (78 emu/g) of BaFe2W was approximately 10% higher than that of the M-type hexaferrite, which was widely used as a permanent magnet for ceramics. And the anisotropic field (16 kOe) was almost equal. Therefore, in the early stage, W-type ferrite was studied as permanent magnet [3–5]. Unfortunately, their coercivity was reported to have * Hao He [email protected] * Yimin Li [email protected] 1
Research Center of Materials Science and Engineering, Guangxi University of Science and Technology, Liuzhou 545006, People’s Republic of China
Center of Experimental Teaching for Common Courses, Panzhihua University, Panzhihua 617000, People’s Republic of China
2
a maximum value of 3600 Oe [6], well below the coercivity of M-type ferrite (5000 Oe). In recent years, due to their moderate permeability and high ferromagnetic resonance frequency, many research teams have attempted to study their applicability as antennas and microwave absorbers [7–13]. Most studies on W-type hexaferrites focus on the substitution of ternary or quaternary compounds for W-type hexaferrites, which is closely related to the phase stability of W-type hexaferrites [14]. At present, as far as we know, there are few reports on the preparation of F e2W ferrite by solid-phase method. The reason is that Fe2+ is easy to oxidize into F e3+, which makes the experiment more difficult [2, 15
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