Mechanosynthesis, crystal structure and magnetic characterization of M-type SrFe12O19 (original) (raw)
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Nanomaterials, 2022
In this study, SrFe12-xNdxO19, where x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5, was prepared using high-energy ball milling. The prepared samples were characterized by X-ray diffraction (XRD). Using the XRD results, a comparative analysis of crystallite sizes of the prepared powders was carried out by different methods (models) such as the Scherrer, Williamson–Hall (W–H), Halder–Wagner (H–W), and size-strain plot (SSP) method. All the studied methods prove that the average nanocrystallite size of the prepared samples increases by increasing the Nd concentration. The H–W and SSP methods are more accurate than the Scherer or W–H methods, suggesting that these methods are more suitable for analyzing the XRD spectra obtained in this study. The specific saturation magnetization (σs), the effective anisotropy constant (Keff), the field of magnetocrystalline anisotropy (Ha), and the field of shape anisotropy (Hd) for SrFe12-xNdxO19 (0 ≤ x ≤ 0.5) powders were calculated. The coercivity (Hc) increases (about 9% at x = 0.4) with an increasing degree of substitution of Fe3+ by Nd3+, which is one of the main parameters for manufacturing permanent magnets.
Strontium hexaferrite (SrFe 12 O 19) which crystallizes in the hexagonal system and has a uniaxial mag-netoplumbite structure, displays distinctive magnetic characteristics, good chemical stability, good tribological properties and a weak temperature dependent coercivity at about room temperature. In the present work the synthesis conditions for the solid-state preparation of the chromium-doped hexaferrite SrCr 0.3 Fe 11.7 O 19 were optimised and the effect on the magnetic properties of this compound of additions of nanosized SrFe 12 O 19 was studied. The nano-sized SrFe 12 O 19 additive, synthesized by the citrate–nitrate reaction, was substituted in varying amounts for a commercial calcium silicate borate sintering additive mixture. A combination of 0.75 wt% of nano-sized SrFe 12 O 19 with 0.75 wt% of the commercial additive increases the intrinsic coercivity, remanence magnetization and rectangularity ratio and results in superior magnetic properties than obtained with 1.5 wt% of nanosized SrFe 12 O 19 or the commercial sintering additive alone.
Enhanced structural and magnetic properties of Al–Cr‑substituted SrFe12O19 hexaferrite system
Applied Physics A, 2022
M-type Al–Cr-substituted strontium hexaferrite ( SrFe12-x-yAlxCryO19 where x = y = 0.0, 0.05, 0.1, 0.15, and 0.2) powders are synthesized successfully using sol–gel auto-combustion method. The synthesized powders were sintered at 1200 °C for 2 h, and their structural, morphological, and magnetic properties were studied using characterization techniques like XRD (X-ray diffraction), FTIR (Fourier transform infrared spectroscopy), SEM (scanning electron microscopy), and VSM (vibrating sample magnetometer). The XRD pattern confirmed the formation of single phase hexagonal structure with P63/mmc space group. The saturation magnetization is observed to decrease from 63.37 to 46.89 emu/g with the increase in dopant concentration. However, the coercivity initially decreased and then increased with increase in dopant concentration.