Improved magnetic and electromagnetic absorption properties of xSrFe₁₂O₁₉/(1−x)NiFe₂O₄ composites

Abstract

xSrFe12O19/(1−x)NiFe2O4 composites (0 ≤ x ≤ 1.0) were synthesized by using a conventional solid‐state synthetic route. The results show that magnetic hysteresis loops of the xSrFe12O19/(1−x)NiFe2O4 composites are similar to those of individual component ferrites, except for the 0.1SrFe12O19/0.9NiFe2O4 and 0.3SrFe12O19/0.7NiFe2O4, suggesting that the hard/soft magnetic phases are well exchange‐coupled. The saturation magnetization, coercivity, and remanent magnetization of the xSrFe12O19/(1−x)NiFe2O4 composites are increased with increasing content of SrFe12O19, with maximal values of 42.1 Am2 kg−1, 78.7 kA m−1, 17.2 Am2 kg−1, respectively, as the content x is about 0.5. They are higher than those of the individual components, implying that interface coupling is present in the magnetic composites. The coercivity and remanent magnetization of the composites are increased initially with increasing sintering temperature and then show a downward tendency. For the component SrFe12O19 and NiFe2O4, the minimum reflection losses are −12.5 dB and −18.3 dB at match thicknesses of 2.5 mm and 2 mm, respectively. Compared with those of the component SrFe12O19 and NiFe2O4, the microwave absorption performances of the xSrFe12O19/(1−x)NiFe2O4 composites are improved remarkably, especially for the samples of x = 0.3 and x = 0.9. The minimum reflection losses values of the 0.3SrFe12O19/0.7NiFe2O4 composite are −31.6 dB (12.7 GHz) and −20.2 dB (13 GHz), while those of the 0.9SrFe12O19/0.1NiFe2O4 composites are −23.7 dB (16.3 GHz) and −33.5 dB (15.8 GHz), as the matching thicknesses are 2.5 mm and 2 mm, respectively. Therefore, the xSrFe12O19/(1−x)NiFe2O4 composites could be used as potential microwave absorption materials.

Effects of Ca–Gd co‐substitution on the structural, magnetic, and dielectric properties of M‐type strontium hexaferrite

“…The electrical modulus is a recommended method to interpret the electrical transport mechanism and the relaxation processes. The electric modulus M*(ω) is defined as 71 𝑀 * = 𝑀 ′ + 𝑖𝑀 ′′ (9) where M′(ω) and M″(ω) are real and imaginary parts of the electrical modulus, calculated from the following relation:…”

“…As an individual hexaferrite material cannot meet the demands of strong absorption, broad bandwidth, and thin thickness, in this regard, hard/soft composites are expected to be excellent microwave absorbers. 9,10 Partial co-substitution for Fe 3+ and Sr 2+ in the M-type hexaferrite has been carried out by several researchers to achieve the physical properties optimized for the applications. [11][12][13][14][15][16] Liaquat et al 17 reported dielectric and magnetic properties of Sr 0.5 Ba 0.5 Fe 12−x Gd x O 19 nanoparticles.…”

“…They observed that the reflection loss improved with the increasing doping percentage. As an individual hexaferrite material cannot meet the demands of strong absorption, broad bandwidth, and thin thickness, in this regard, hard/soft composites are expected to be excellent microwave absorbers 9,10 …”

Tuning the Structure, Magnetic, and High Frequency Properties of Sc‐Doped Sr0.5Ba0.5ScxFe12‐xO19/NiFe2O4 Hard/Soft Nanocomposites

“…Thus, the spins of two phases switch jointly with the magnetic field, pointing to the excellent exchange coupling effect that occurred. [57] Moreover, the M data is derived with respect to the H data for all the prepared NCs, and their dM/dH versus H curves are represented in Figure 6. It is clear, at both 300 and 10 K, that two peaks have appeared on the curves of SrBaSc/NiFe H/S (x = 0.00) NCs.…”

Enhanced X and Ku band microwave absorption powered by a magnetic–dielectric synergistic effect in Pr-doped M/W composite hexaferrites

“…At the same time, other researchers have conducted research on ferrite/ferrite composites for microwave absorption, 19–23 and the research hotspot is the M-type/spinel composite system, but according to reports, the microwave absorption performance needs further improvement. 24,25…”