Effect of the Fe/Ba and Fe/Sr ratios on the phase composition, dielectric properties and magnetic characteristics of M-type hexaferrites prepared by the hydrothermal method

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

“…A “wasp‐waisted” hysteresis loop is recorded around H = 0 for all the samples, which are some reasons for this behavior 44–46 . This behavior indicates the distribution of coercive force, which can be caused by the bimodal grain distribution, dipolar interactions between single‐domain nanoparticles, the presence of superparamagnetic fraction, or the coexisting of different magnetic phases 46,47 . Such a behavior around H = 0 was observed in the hysteresis loops of cobalt ferrite nanoparticles (CoFe 2 O 4 ) that exhibit the spin reorientation at low temperatures due to canted spins on the surfaces of the nanoparticles 48 .…”

“…Such a behavior around H = 0 was observed in the hysteresis loops of cobalt ferrite nanoparticles (CoFe 2 O 4 ) that exhibit the spin reorientation at low temperatures due to canted spins on the surfaces of the nanoparticles 48 . The presence of BaFe 2 O 4 and SrFeO 3− x leads to wasp‐waisted hysteresis loops, which indicates that these phases are not interact with hexaferrite, whereas the samples with hematite are characterized by regular hysteresis loops, which indicates a strong coupling between α‐Fe 2 O 3 and hexaferrite 47 . Chithra et al 49 .…”

“…[44][45][46] This behavior indicates the distribution of coercive force, which can be caused by the bimodal grain distribution, dipolar interactions between single-domain nanoparticles, the presence of superparamagnetic fraction, or the coexisting of different magnetic phases. 46,47 Such a behavior around H = 0 was observed in the hysteresis loops of cobalt ferrite nanoparticles (CoFe 2 O 4 ) that exhibit the spin reorientation at low temperatures due to canted spins on the surfaces of the nanoparticles. 48 The presence of BaFe 2 O 4 and SrFeO 3−x leads to wasp-waisted hysteresis loops, which indicates that these phases are not interact with hexaferrite, whereas the samples with hematite are characterized by regular hysteresis loops, which indicates a strong coupling between α-Fe 2 O 3 and hexaferrite.…”

“…48 The presence of BaFe 2 O 4 and SrFeO 3−x leads to wasp-waisted hysteresis loops, which indicates that these phases are not interact with hexaferrite, whereas the samples with hematite are characterized by regular hysteresis loops, which indicates a strong coupling between α-Fe 2 O 3 and hexaferrite. 47 Chithra et al 49 reported that two sets of particles with different anisotropies yielded the wasp-waisted behavior of the cobalt ferrite nanoparticles. Because no additional peaks due to any impurity phase are observed in the XRD patterns of all the samples, thus reasons for this behavior can be (1) the presence of a large distribution of nanoparticles with different anisotropies, and (2) probably more possible, the simultaneous presence of multi-domain and single-domain grains.…”

Achieving Superior Electromagnetic-Absorbing Performances in the Hexagonal Flake BaFe12O19@PVDF Composites

“…Grain size is an important factor influencing H C and M s , and larger grain sizes result in higher saturation magnetization. − The hydrothermal synthesis of BaFe 12 O 19 is usually carried out under low temperatures (220 °C) and high-pressure reaction conditions without calcining the powder. In contrast, the traditional BaFe 12 O 19 synthesis method requires a high temperature ( T > 1000 °C) to calcine the powders, whereas the hydrothermal method produces smaller-sized BaFe 12 O 19 particles. , Smaller particles provide a greater surface area, which increases the magnetic exchange interactions between particles, thereby reducing coercivity. Furthermore, smaller particles may have more defects at the magnetic domain walls, making them more prone to flipping, leading to lower coercivity.…”