Effect of grain size on electric transport and magnetic behavior of strontium hexaferrite (SrFe12O19)

Sahu, P. K.; Tripathy, Satya Narayan; Pattanayak, Ranjit; Muduli, Rakesh; Mohapatra, Niharika; Panigrahi, S.

doi:10.1007/s00339-016-0601-y

Cited by 13 publications

(2 citation statements)

References 35 publications

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“…This is because the B r value is limited to the saturation magnetic induction (B s ) on the B-H loop, which corresponds to the M S value on the M-H curve. Additionally, the H c value depends not only on the grain size but also on K u [1,8,9]. Sometimes, the magnetic anisotropy field (H a ) is a more convenient representation of the strength of magnetic anisotropy along the easy axis than K u because H a is proportional to K u , as shown by the relationship H a = 2K u /M S for a spherical single domain particle [10].…”

Section: Introductionmentioning

confidence: 99%

Effects of La-Co Co-Substitution on the Structural and Magnetic Properties of SrM Hexaferrites Prepared by Solid-State Reaction

Lee,

Kang,

Yoo

2024

Applied Sciences

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The effects of La-Co co-substitution on the structural and magnetic properties of strontium M-type hexaferrites (SrM) were carefully investigated for the Sr1−xLaxFe12−xCoxO19 (0.0 ≤ x ≤ 0.3) polycrystalline samples prepared by solid-state reaction in air. Without the use of sintering additives, La-Co co-substituted SrM single phases could be obtained from polycrystalline bulk samples by employing proper processing conditions. The lattice parameter a initially increases with increasing x from 0.0 to 0.1 but gradually decreases with increasing x to 0.20, and then remains almost unaltered up to x = 0.3; the lattice parameter c monotonously decreases with increasing x from 0.0 to 0.25, but it turns to an increase when x = 0.3. The reduction in c/a ratios and Vcell values with increasing x up to x = 0.25 are obviously attributable to the decreasing size effect resulting from La3+ substitution at the Sr2+ site, which surpasses the increasing size effect due to Co2+ and Fe2+ occupancy at the Fe3+ site. Meanwhile, with increasing x from 0.0 to 0.3, while the saturation magnetization (MS) continuously decreases from 75.90 to 72.07 emu/g, the magnetic anisotropy field (Ha) increases from 20.1 to 24.7 kOe, leading to an increase in the intrinsic coercivity (Hci) from 2.68 to 3.99 kOe. The gradual increase in Ha with x, probably caused by a gradual decrease in the crystallographic symmetry, is inversely proportional to the variation in the c/a ratios up to x = 0.25 as usual except when x = 0.3, of which deviation needs further study.

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Section: Introductionmentioning

confidence: 99%

Effects of La-Co Co-Substitution on the Structural and Magnetic Properties of SrM Hexaferrites Prepared by Solid-State Reaction

Lee,

Kang,

Yoo

2024

Applied Sciences

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“…In order to provide the nanocomposite magnets with high Hc and Ms values through the magnetic spring effect, the soft magnetic phase must have a mean crystallite size twice the width of the domain wall of the hard magnetic phase [15]. Sahu et al [16] prepared M-type strontium hexaferrite (SHF), SrFe12O19, by a conventional ceramic route to obtain large SHF grains, and used the automatic combustion method to obtain small grains. The magnetic SHF phase with a large size (41.35 nm) produces a value of Hc = 3662 Oe and Ms = 70 emu/g, while a small size produces a higher Hc value of 5842 Oe, but with a lower Ms value of 61 emu/g.…”

Section: Introductionmentioning

confidence: 99%

Physical and Magnetic Characterization of Hard/Soft SrFe12O19/CoFe2O4 Nanocomposite Magnets Made by Mechanical Alloying and Ultrasonic Irradiation

Idayanti

Dedi

Manaf

2021

JNanoR

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In this study, the particle sizes of SrFe12O19 in hard/soft SrFe12O19/CoFe2O4 nanocomposite magnets made using mechanical alloying and ultrasonic irradiation were investigated. SrFe12O19/CoFe2O4 nanocomposites were combined in a ratio of 75:25, with each magnetic material being prepared separately. SrFe12O19 powder was prepared from Fe2O3 and SrCO3 powder by mechanical alloying and ultrasonic irradiation for different times, 0, 3, 6, 9, and 12 h. Varying the ultrasonic time during the preparation of the SrFe12O19 samples resulted in differences in morphological characteristics, crystal structure, particle size, crystal size, microstrain, density, porosity, and magnetic properties. The longer the ultrasonic time, the crystal size and particle size decreases, the density increases, and the porosity reduction which affects the magnetic properties. SrFe12O19 after 12 h ultrasonic process reach Ms value = 61.29 emu/g. CoFe2O4 powder was produced from Fe2O3 and CoCO3 powder by mechanical alloying with a 10 h milling time. Furthermore, each SrFe12O19 sample was composited with CoFe2O4 powder by ultrasonic irradiation for 1 h and these composite samples also showed different characteristics, where there is an increase in Mr and Ms compared to the single SrFe12O19. The morphology, crystal structure, particle size, and magnetic properties of the samples were measured using scanning electron microscopy, X-ray diffraction, particle size analysis, and PERMAGRAPH. The crystal size and microstrain were calculated using a Williamson–Hall plot, and density and porosity were determined using Archimedes’ law.

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Reduced Graphene Oxide Functionalized Strontium Ferrite in Poly(3,4‐ethylenedioxythiophene) Conducting Network: A High‐Performance EMI Shielding Material

Dalal

Lather

Gupta

et al. 2019

Adv Materials Technologies

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The advent of nanotechnology leading to high‐frequency device realization has resulted in a rapid increase in radiation pollution. The synthesis of core–shell morphology based poly(3,4‐ethylenedioxythiophene) (PEDOT)/ reduced graphene oxide (RGO) nanocomposites incorporated with SrFe12O19 nanoparticles via in situ emulsion polymerization is a step to control ever‐increasing radiation pollution. For electromagnetic (EM) shielding, impedance matching, and absorption of EM wave being the two key parameters. RGO and PEDOT establish an interconnected conducting network inside the PEDOT matrix and the resulting conductive pathway provides better impedance matching for the incident radiation. The RGO sheets decorated with ferrite nanoparticles strengthen the mechanism of the shielding by absorbing incoming EM radiation. The synergic coupling of the magneto‐dielectric characteristics of nanocomposites result in high electromagnetic shielding effectiveness (SE) of 42.29 dB at 12.4 GHz for 2.5 mm thick sample. The SE is mainly dominated by absorption and also measured as a function of thickness resulting in SE(max) value of 62 dB at a thickness of 4.66 mm. The present set of nanocomposites are found to exhibit attenuation of more than 99.999% and have the potential for commercial application in EM shielding.

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Effect of grain size on electric transport and magnetic behavior of strontium hexaferrite (SrFe12O19)

Cited by 13 publications

References 35 publications

Effects of La-Co Co-Substitution on the Structural and Magnetic Properties of SrM Hexaferrites Prepared by Solid-State Reaction

Effects of La-Co Co-Substitution on the Structural and Magnetic Properties of SrM Hexaferrites Prepared by Solid-State Reaction

Physical and Magnetic Characterization of Hard/Soft SrFe<sub>12</sub>O<sub>19</sub>/CoFe<sub>2</sub>O<sub>4</sub> Nanocomposite Magnets Made by Mechanical Alloying and Ultrasonic Irradiation

Reduced Graphene Oxide Functionalized Strontium Ferrite in Poly(3,4‐ethylenedioxythiophene) Conducting Network: A High‐Performance EMI Shielding Material

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