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Journal articles on the topic 'SrFe12O19'

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Author: Grafiati
Published: 4 June 2021
Last updated: 31 January 2023

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1

Idayanti, Novrita, Dedi, and Azwar Manaf. "Physical and Magnetic Characterization of Hard/Soft SrFe12O19/CoFe2O4 Nanocomposite Magnets Made by Mechanical Alloying and Ultrasonic Irradiation." Journal of Nano Research 69 (August 30, 2021): 53–66. http://dx.doi.org/10.4028/www.scientific.net/jnanor.69.53.

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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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2

Li, Qiao Ling, Cun Rui Zhang, and Yun Ye. "Preparation and Properties Analysis of Polyaniline/Nano-SrFe12O19 Composites with Different Morphologies." Advanced Materials Research 79-82 (August 2009): 1607–10. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.1607.

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Polyaniline/nano-SrFe12O19 composites were prepared by in situ polymerization method for the first time. Rod-like and flower-like morphologies composites were synthesized in the phase of an emulsion polymerization system. It was found that the morphology of obtained PANI/nano-SrFe12O19 composites depended on the content of SrFe12O19 of the reaction system. A possible mechanism for the formation of the different morphologic composites had been proposed. The magnetic properties of the PANI/nano- SrFe12O19 composites were inspected by VSM. The possible mechanism for magnetic variation had been proposed in the paper.
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3

Laayati, Mouhsine, Ayoub Abdelkader Mekkaoui, Lahcen Fkhar, Mustapha Ait Ali, Hafid Anane, Lahoucine Bahsis, Larbi El Firdoussi, and Soufiane El Houssame. "Synergistic effect of GO/SrFe12O19 as magnetic hybrid nanocatalyst for regioselective ring-opening of epoxides with amines under eco-friendly conditions." RSC Advances 12, no. 18 (2022): 11139–54. http://dx.doi.org/10.1039/d2ra00984f.

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Highly efficient magnetically separable hybrid GO/SrFe12O19 nanocomposite was synthesized, as catalyst for epoxide ring-opening, via dispersing M-type strontium hexaferrite (SrFe12O19) on graphene oxide (GO) sheets.
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4

Liu, Jian An, Mei Mei Zhang, Yan Fei Zhang, and Shu Jiang Liu. "Synthesis and Characterization of Nano-Hexaferrites SrFe12O19 by Aqueous Solution Method." Advanced Materials Research 306-307 (August 2011): 404–9. http://dx.doi.org/10.4028/www.scientific.net/amr.306-307.404.

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Nano-hexaferrite SrFe12O19 has been prepared using the aqueous solution method. The structure and magnetic properties of SrFe12O19 have systematically been investigated by X-ray diffraction (XRD), Thermo gravimetric (TG), Fourier transform infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM), as well as Vibrating Sample Magnetometer (VSM). The XRD and TEM results showed that the samples are composed of SrFe12O19 nano-particles which are on average 70×50nm in dimensions when treated at 1200°C for 2 hours. The magnetic properties indicated that the saturation magnetization and the intrinsic coercivity were 48 Am2/kg and 506KA/m, respectively. The aqueous solution method is generally applicable to produce the nano-hexaferrite SrFe12O19 and is proved to be a promising method for fast synthesis of nanometer materials using nitrate.
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5

Karahroudi, Zahra Hajian, Kambiz Hedayati, and Mojtaba Goodarzi. "Green synthesis and characterization of hexaferrite strontium-perovskite strontium photocatalyst nanocomposites." Main Group Metal Chemistry 43, no. 1 (April 29, 2020): 26–42. http://dx.doi.org/10.1515/mgmc-2020-0004.

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AbstractThis study presents a preparation of SrFe12O19– SrTiO3 nanocomposite synthesis via the green auto-combustion method. At first, SrFe12O19 nanoparticles were synthesized as a core and then, SrTiO3 nanoparticles were prepared as a shell for it to manufacture SrFe12O19–SrTiO3 nanocomposite. A novel sol-gel auto-combustion green synthesis method has been used with lemon juice as a capping agent. The prepared SrFe12O19–SrTiO3 nanocomposites were characterized by using several techniques to characterize their structural, morphological and magnetic properties. The crystal structures of the nanocomposite were investigated via X-ray diffraction (XRD). The morphology of SrFe12O19– SrTiO3 nanocomposite was studied by using a scanning electron microscope (SEM). The elemental composition of the materials was analyzed by an energy-dispersive X-ray (EDX). Magnetic properties and hysteresis loop of nanopowder were characterized via vibrating sample magnetometer (VSM) in the room temperature. Fourier transform infrared spectroscopy (FTIR) spectra of the samples showed the molecular bands of nanoparticles. Also, the photocatalytic behavior of nanocomposites has been checked by the degradation of azo dyes under irradiation of ultraviolet light.
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6

Sun, Wei-Feng, and Peng-Bo Sun. "Electrical Insulation and Radar-Wave Absorption Performances of Nanoferrite/Liquid-Silicone-Rubber Composites." International Journal of Molecular Sciences 23, no. 18 (September 9, 2022): 10424. http://dx.doi.org/10.3390/ijms231810424.

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Novel radar-wave absorption nanocomposites are developed by filling the nanoscaled ferrites of strontium ferroxide (SrFe12O19) and carbonyl iron (CIP) individually into the highly flexible liquid silicone rubber (LSR) considered as dielectric matrix. Nanofiller dispersivities in SrFe12O19/LSR and CIP/LSR nanocomposites are characterized by scanning electronic microscopy, and the mechanical properties, electric conductivity, and DC dielectric-breakdown strength are tested to evaluate electrical insulation performances. Radar-wave absorption performances of SrFe12O19/LSR and CIP/LSR nanocomposites are investigated by measuring electromagnetic response characteristics and radar-wave reflectivity, indicating the high radar-wave absorption is dominantly derived from magnetic losses. Compared with pure LSR, the SrFe12O19/LSR and CIP/LSR nanocomposites represent acceptable reductions in mechanical tensile and dielectric-breakdown strengths, while rendering a substantial nonlinearity of electric conductivity under high electric fields. SrFe12O19/LSR nanocomposites provide high radar-wave absorption in the frequency band of 11~18 GHz, achieving a minimum reflection loss of −33 dB at 11 GHz with an effective absorption bandwidth of 10 GHz. In comparison, CIP/LSR nanocomposites realize a minimum reflection loss of −22 dB at 7 GHz and a remarkably larger effective absorption bandwidth of 3.9 GHz in the lower frequency range of 2~8 GHz. Radar-wave transmissions through SrFe12O19/LSR and CIP/LSR nanocomposites in single- and double-layered structures are analyzed with CST electromagnetic-field simulation software to calculate radar reflectivity for various absorbing-layer thicknesses. Dual-layer absorbing structures are modeled by specifying SrFe12O19/LSR and CIP/LSR nanocomposites, respectively, as match and loss layers, which are predicted to acquire a significant improvement in radar-wave absorption when the thicknesses of match and loss layers approach 1.75 mm and 0.25 mm, respectively.
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7

Zhang, Ze Yang, Xiang Xuan Liu, and You Peng Wu. "Synthesis, Characterization, and Microwave Absorption Properties of SrFe12O19 Ferrites and FeNi3 Nanoplatelets Composites." Advanced Materials Research 148-149 (October 2010): 893–96. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.893.

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M-typical SrFe12O19 ferrites and FeNi3 nanoplatelets were successfully prepared by the sol-gel method and solution phase reduction method, respectively. The crystalline and morphology of particles were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The composite coatings with SrFe12O19 ferrites and FeNi3 nanoplatelets in polyvinylchloride matrix were prepared. The microwave absorption properties of these coatings were investigated in 2-18GHz frequency range. The results showed that the M-typical SrFe12O19 ferrites and FeNi3 nanoplatelets were obtained and they presented irregular sheet shapes. With the increase of the coating thickness, the absorbing peak value moves to the lower frequency. The absorbing peak values of the wave increase along with the increasing of the content of FeNi3 nanoplatelets filling fraction. When 40% SrFe12O19 ferrites is doped with 20% mass fraction FeNi3 nanoplatelets to prepare composite with 1.5mm thickness, the maximum reflection loss is -24.8 dB at 7.9GHz and the -10 dB bandwidth reaches 3.2GHz.
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8

Laayati, Mouhsine, Ali Hasnaoui, Nayad Abdallah, Saadia Oubaassine, Lahcen Fkhar, Omar Mounkachi, Soufiane El Houssame, Mustapha Ait Ali, and Larbi El Firdoussi. "M-Type SrFe12O19 Ferrite: An Efficient Catalyst for the Synthesis of Amino Alcohols under Solvent-Free Conditions." Journal of Chemistry 2020 (July 11, 2020): 1–10. http://dx.doi.org/10.1155/2020/7960648.

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Magnetically separable strontium hexaferrite SrFe12O19 was prepared using the chemical coprecipitation method, and the nanostructured material was characterized by X-ray diffraction, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), and BET analysis. The SEM images showed the homogeneity of the chemical composition of SrFe12O19 and uniform distribution of size and morphology. The pore size of the nanomaterial and its specific area were determined by BET measurements. Strontium hexaferrite SrFe12O19 exhibited a strong magnetic field, which is highly suitable in the heterogeneous catalysis as it can be efficiently separated from the reaction. The magnetic nanocatalyst showed high activity and environmentally benign heterogeneous catalysts for the epoxide ring-opening with amines affording β-amino alcohols under solvent-free conditions. When unsymmetrical epoxides were treated in the presence of aromatics amines, the regioselectivity was influenced by the electronic and steric factors. Total regioselectivity was observed for the reactions performed with aliphatic amines. The magnetically SrFe12O19 nanocatalyst showed excellent recyclability with continuously good catalytic activities after four cycles.
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9

Guo, Wei, Hang Wu, Zhen Zhong Zheng, Qing Chang Chen, and Qing Guo Chu. "The Research of by Blend and Flux Method SrFe12O19 Magnetic Particle Preparation and Magnetic Properties." Advanced Materials Research 160-162 (November 2010): 1513–17. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.1513.

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According to the influence of sintering time, sintering temperature, different amount of flux and different molar ratio of Fe / Sr to the magnetic properties of prepared SrFe12O19 magnetic particles, the optimum SrFe12O19 conditions were concluded. They are: sintering time: 3 hours; sintering temperature: 1073.15 k; flux NaCl amount: 15% wt of the reaction raw materials; Fe / Sr molar ratio: 11.4; the sample magnetic properties: Ms = 63.39emu / g; Mr = 33.44emu / g; Hc = 5798Oe, Mr / Ms = 1 : 1.90 ≈ 1:2. The prepared SrFe12O19 should be single crystal particles and in the shape of flake, and the particle size should be generally about 80-90nm with uniform distribution.
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10

Kubisztal, Marian, Artur Chrobak, Julian Kubisztal, Jozef Stabik, Agnieszka Dybowska, and Grzegorz Haneczok. "Magnetic and Elastic Properties of Nanocomposites Containing Soft (Ni) and Hard (SrFe12O19) Magnetic Particles." Solid State Phenomena 203-204 (June 2013): 310–14. http://dx.doi.org/10.4028/www.scientific.net/ssp.203-204.310.

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In the present paper magnetic and elastic properties of the Ni+SrFe12O19 nanocomposites were examined in detail. Samples were in two forms: i) mechanically pressed cylindrical pellets and ii) filled polymer (amine-epoxy resin) coating on aluminum substrate. The so called apparent Young’s modulus was determined by measurements of the free flexural vibrations frequency by means of vibrating reed technique. Magnetic research was carried out using VSM magnetometer. It was shown that replacement of SrFe12O19 with nano Ni powder results in an increase in material resistivity to elastic deformation. The influence of size reduction of SrFe12O19 powder particles on magnetic parameters of the studied nanocomposites were discussed in detail.
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11

Granados, Cecilia, Espen Bøjesen, Kirsten Jensen, and Mogens Christensen. "In situ growth of SrFe12O19." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C505. http://dx.doi.org/10.1107/s2053273314094947.

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SrFe12O19 is a highly anisotropic ferrimagnetic compound with relatively high remanence and high coercivity, which is used in permanent magnets. Permanent magnets are everywhere in our daily life and they are responsible for the interconversion between motion and electricity in electrical components ranging from headphones to wind turbines. Three key parameters, important for making permanent magnets, are an anisotropic structure, size of the nanocrystallites and the microstructure. In situ X-ray powder diffraction has been used to follow the growth kinetics of SrFe12O19 under hydrothermal conditions. Synthesis of SrFe12O19 (Sr-Hexaferrite) nanocrystals by hydrothermal methods have the advantage of allowing exhaustive control of the reaction parameters. We have studied the growth and kinetics of SrFe12O19 by carring out time resolved synchrotron experiments at MAX-lab, Sweden. The experiments were carried out at elevated pressure (250 bar) and in temperatures ranging from 250 to 400 oC. The diffraction data allow us to follow the evolution of the crystallite size as function of temperature, time and composition. By controlling the composition of the precursor we can tailor the size of the nanocrystallites. The obtained data have shown that the synthesis takes place through a conversion of tiny hexagonal shaped FeOOH nanocrystallites into the SrFe12O19. Several ex situ studies under comparable conditions have been carried out to compare the magnetic properties and the obtained nanocrystallites have been investigated using high resolution laboratory powder diffraction data.
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12

Kolev, Svetoslav, Tatyana Koutzarova, Andrey Yanev, Chavdar Ghelev, and Ivan Nedkov. "Microwave Properties of Polymer Composites Containing Combinations of Micro- and Nano-Sized Magnetic Fillers." Journal of Nanoscience and Nanotechnology 8, no. 2 (February 1, 2008): 650–54. http://dx.doi.org/10.1166/jnn.2008.b069.

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We investigated the microwave absorbing properties of composite bulk samples with nanostructured and micron-sized fillers. As magnetic fillers we used magnetite powder (Fe3O4 with low magnetocrystalline anisotropy) and strontium hexaferrite (SrFe12O19 with high magnetocrystalline anisotropy). The dielectric matrix consisted of silicone rubber. The average particle size was 30 nm for the magnetite powder and 6 μm for the strontium hexaferrite powder. The micron-sized SrFe12O19 powder was prepared using a solid-state reaction. We investigated the influence of the filler concentration and the filler ratio (Fe3O4/SrFe12O19) in the polymer matrix on the microwave absorption in a large frequency range (1 ÷ 18 GHz). The results obtained showed that the highly anisotropic particles become centers of clusterification and the small magnetite particles form magnetic balls with different diameter depending on the concentration. The effect of adding micron-sized SrFe12O19 to the nanosized Fe3O4 filler in composites absorbing structures has to do with the ferromagnetic resonance (FMR) shifting to the higher frequencies due to the changes in the ferrite filler's properties induced by the presence of a magnetic material with high magnetocrystalline anisotropy. The two-component filler possesses new values of the saturation magnetization and of the anisotropy constant, differing from those of both SrFe12O19 and Fe3O4, which leads to a rise in the effective anisotropy field. The results demonstrate the possibility to vary the composite's absorption characteristics in a controlled manner by way of introducing a second magnetic material.
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13

Li, Min, Zhou Wang, Hong Bo Liu, and Xiang Qian Shen. "Electromagnetic and Microwave Absorption of Nanocrystalline Alloy Fe0.2(Co0.2Ni0.8)0.8 and Nanocomposite SrFe12O19/Ni0.5Zn0.5Fe2O4 Microfibers." Advanced Materials Research 1035 (October 2014): 355–60. http://dx.doi.org/10.4028/www.scientific.net/amr.1035.355.

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Magnetic nanocrystalline alloy Fe0.2(Co0.2Ni0.8)0.8 microfibers and nanocomposite SrFe12O19/Ni0.5Zn0.5Fe2O4 microfibers are used as the absorbents in the double-layer structure for microwave absorption. The double-layer absorbers with a total thickness of 2 mm consisting of Fe0.2(Co0.2Ni0.8)0.8 and nanocomposite SrFe12O19/Ni0.5Zn0.5Fe2O4 microfibers are designed, and their microwave absorption properties are predicted based on the electromagnetic parameter measurements. The results show that the double-layer absorber with the absorption layer of SrFe12O19/Ni0.5Zn0.5Fe2O4 microfibers and the thickness of 0.6 mm has the best microwave absorption properties, with the bandwidth ( the reflection loss less than −10 dB) of 7.3 GHz ranging from 10.7 GHz to 18 GHz, and the maximum reflection loss of −71.4 dB at 12.1 GHz.
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14

Zhu, Xiaolei, Xiaoping Wang, Kuili Liu, Honglei Yuan, Reza Boudaghi, and Majid Niaz Akhtar. "Thickness optimization towards microwave absorption enhancement in three-layer absorber based on SrFe12O19, SiO2@SrFe12O19 and MWCNTs@SrFe12O19 nanocomposites." Journal of Alloys and Compounds 873 (August 2021): 159818. http://dx.doi.org/10.1016/j.jallcom.2021.159818.

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15

Chaya, Pannipa, Tula Jutarosaga, and Wandee Onreabroy. "Structure and Magnetic Properties of Co-Substituted Strontium Hexaferrite." Advanced Materials Research 979 (June 2014): 200–203. http://dx.doi.org/10.4028/www.scientific.net/amr.979.200.

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The strontium hexaferrite (SrFe12O19) and Co-substituted strontium hexaferrite (SrCoFe11O19) were prepared by ceramic method. The milled mixture of Fe2O3, SrCO3 and CoO powders were calcined at 1100°C and pellets sintered at 1300°C in air. The crystal structure, morphology and magnetic properties of samples have been investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer (VSM), respectively. The crystal structure of SrFe12O19 was hexaferrite with the crystallite size and the lattice constants a and c of 59.6 nm, 5.8 Å, and 23.0 Å, respectively. Also, the crystal structure of SrCoFe11O19 was hexaferrite with the crystallite size and the lattice constants a and c of 63.7 nm, 5.9 Å and 23.0 Å, respectively. The morphology of obtained samples changed from hexagonal rods to discs shape and grain sizes increased with the increase of doped Co in SrFe12O19. SrFe12O19 with the coercive force (Hc) of 2,133 Oe was classified as hard ferrite magnetic. While, Co-substituted strontium hexaferrite (SrCoFe11O19) was soft ferrite magnetic with coercive force of 64 Oe. Results indicated that magnetic properties of samples such as hard ferrite magnetic and soft ferrite magnetic showed great dependence on the cobalt additive in strontium.
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16

Bavarsiha, Fatemeh, Saeideh Dadashian, Mehdi Montazeri-Pour, Fardin Ghasemy-Piranloo, and Masoud Rajabi. "Synthesis, characterization and photocatalytic efficiency of Fe3O4/SiO2/TiO2, SrFe12O19/SiO2/TiO2 and Fe3O4/SiO2/ZnO core/shell/shell nanostructures." Processing and Application of Ceramics 16, no. 3 (2022): 291–301. http://dx.doi.org/10.2298/pac2203291b.

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In this research, three magnetically separable photocatalysts, Fe3O4/SiO2/TiO2, SrFe12O19/SiO2/TiO2 and Fe3O4/SiO2/ZnO, with core/shell/shell structures were successfully prepared. In the first step, soft magnetic and hard magnetic Fe3O4 and SrFe12O19 powders were synthesized using carbon reduction and co-precipitation routes, respectively. In the second step, silica coating was performed by controlling the hydrolysis and con- densation of tetraethyl orthosilicate (TEOS) precursor on the magnetic cores. In the third step, a layer of TiO2 or ZnO photocatalytic shells was made on the as-prepared composites using titanium n-butoxide (TNBT) or zinc nitrate hexahydrate, respectively. The formation of the core/shell/shell structures was confirmed by FESEM and TEM analyses. The saturation magnetizations of the Fe3O4/SiO2/TiO2, SrFe12O19/SiO2/TiO2 and Fe3O4/SiO2/ZnO photocatalytic materials were 41.5, 33 and 49 emu/g, respectively. Photocatalytic activity was evaluated by degradation percentages of methylene blue (MB) under UV illumination, which were 88%, 83% and 62%, for the Fe3O4/SiO2/TiO2, SrFe12O19//TiO2 and Fe3O4/SiO2/ZnO composites, respectively. The first-, and second-order reaction kinetics were used to find out the suitable MB removal kinetics.
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17

Mehdipour, M., and H. Shokrollahi. "Comparison of microwave absorption properties of SrFe12O19, SrFe12O19/NiFe2O4, and NiFe2O4 particles." Journal of Applied Physics 114, no. 4 (July 28, 2013): 043906. http://dx.doi.org/10.1063/1.4816089.

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18

Zhang, Jing, Mao Liu, Tao Yang, Kai Yang, and Hongyu Wang. "A novel magnetic biochar from sewage sludge: synthesis and its application for the removal of malachite green from wastewater." Water Science and Technology 74, no. 8 (August 10, 2016): 1971–79. http://dx.doi.org/10.2166/wst.2016.386.

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In this study, a novel magnetic sludge biochar (MSBC) from sewage sludge was created by the assembly of strontium hexaferrite (SrFe12O19) onto the surface of sewage sludge biochar (SBC) under high-temperature and oxygen-free conditions. The characterization of MSBC was achieved by Fourier transform infrared spectroscopy, X-ray diffraction and vibrating sample magnetometry, and the adsorption properties of the MSBC towards malachite green (MG) from aqueous solution were systematically investigated. The influence of variables (different mass ratio of SBC and SrFe12O19, initial MG concentration, absorbent dosage, pH and contact time) was also studied in detail. The optimal adsorption amount of MG (388.65 mg MG/g) was obtained with 500 mg MG/L, 2.0 g MSBC/L for 40 min under pH of 7.0, with different mass ratios of SBC and SrFe12O19 (1:4, 1:2, 3:4 and 1:1), when the mass ratio of SBC and SrFe12O19 was 3:4 at room temperature, and the Langmuir model was more suitable than the Freundlich model for equilibrium data. Meanwhile, the kinetic models showed that the overall adsorption process was better described by a pseudo-second-order kinetic model. The results indicated that the MSBC was a novel, efficient, magnetically separable adsorbent for the removal of the dye from wastewater.
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19

de Campos, Marcos Flavio, Sergio A. Romero, and Daniel Rodrigues. "Estimate of the Anisotropy Field of Strontium Ferrite from Powders Using the Stoner-Wohlfarth Model." Materials Science Forum 881 (November 2016): 128–33. http://dx.doi.org/10.4028/www.scientific.net/msf.881.128.

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The isotropic Stoner-Wohlfarth model can be applied for the determination of the anisotropy field in powders. Samples of strontium ferrite - SrFe12O19 – were measured in Vibrating Sample Magnetometer (VSM). By means of the fitting of the first quadrant of the hysteresis curve the anisotropy field was estimated as 19-20 kOe for the SrFe12O19 phase. The main advantage of the method is its simplicity, because compacting or sintering of the powder samples is not necessary
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20

Panchal, Nital R., and Rajshree B. Jotania. "Effect of Heat Treatment on Microstructure and Magnetic Properties of Strontium Hexaferrite Nanoparticles Prepared in Presence of Non-Ionic Surfactant." Solid State Phenomena 202 (May 2013): 193–205. http://dx.doi.org/10.4028/www.scientific.net/ssp.202.193.

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SrFe12O19 hexaferrite particles containing polyoxyethelene (20) sorbitan monolate (Tween-80) were synthesized by a chemical co-precipitation technique with a precipitator NH3.H2O. The prepared Sr-M hexaferrite precipitates were heat treated at various temperatures 650 oC, 750 oC, 850 oC, 950oC and 1100oC for 4 hrs in a muffle furnace. The obtained Sr-M powders were characterized by using various instrumental techniques, like FTIR, TGA, XRD, SEM, VSM and Mössbauer spectroscopy. Their physical as well as Magnetic properties were compared. It was observed from XRD results that heat treatment conditions play significant role in the formation of pure SrFe12O19 hexaferrite phase and also in the grain size. The estimated particle size is of the order of nanometer when suitable calcination temperature is applied. SEM micrographs show an increase in crystallite size of the resultant SrFe12O19 hexaferrite particles sintered at higher temperature (1100 oC). Mössbauer spectroscopic measurements were carried out at room temperature. Mössbauer analysis indicates the presence Fe3+ ions in the prepared strontium hexaferrite particles.
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21

Kong, Sifang, Jiang Cheng, Yangsheng Liu, Xiufang Wen, Pihui Pi, and Zhuoru Yang. "Synthesis of functional magnetic porous SrFe12O19/P(St-DVB-MAA) microspheres by a novel suspension polymerization." Open Chemistry 6, no. 4 (December 1, 2008): 627–33. http://dx.doi.org/10.2478/s11532-008-0055-y.

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AbstractIn this study, a novel and effective suspension polymerization has been employed to prepare functional magnetic porous SrFe12O19/P(St-DVB-MAA) microspheres in the presence of bilayer surfactants (sodium dodecyl benzene sulfonate (SDBS) and oleic acid (OA)) coated on micro-size magnetic SrFe12O19. This was achieved by pre-polymerizing the organic phase, which contained co-monomers, porogens and treated magnetic particles, at 65°C for 0.5 h under ultrasound conditions. Aqueous solutions containing a dispersion agent were then added to effect suspension polymerization. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and magnetic property measurement system (MPMS) were used to characterize the functional magnetic porous microspheres. The results show that the microparticles are well shaped with a uniform size distribution of about 0.5 ∼ 0.7 mm and the surfaces of the microspheres have many micro-pores with an average diameter of 0.533 µm. There are carboxyl groups (−COOH) on the surface of the microspheres to the extent of 0.65 mmol g−1, as determined by conductometric titration. According to the XRD spectra, iron oxide consists mainly of SrFe12O19 which reveals hexahedral structure. The content of magnetic SrFe12O19 reaches 17.81% (by mass), and the microspheres have good heat resistance. The magnetic porous microspheres are ferromagnetic with high residual magnetization and coercivity, 21.59 emu g−1 and 4.13 kOe, respectively. The saturation magnetisation is around 42.85 emu g−1.
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22

Rakshit, S. K., S. C. Parida, S. Dash, Z. Singh, R. Prasad, and V. Venugopal. "Thermochemical studies on SrFe12O19(s)." Materials Research Bulletin 40, no. 2 (February 2005): 323–32. http://dx.doi.org/10.1016/j.materresbull.2004.10.015.

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23

Teng, Shian Cheau, Yung-Tsen Chien, and Yung-Chao Ko. "Nonisothermal sintering of SrFe12O19 ferrite." Journal of Materials Science Letters 14, no. 7 (1995): 519–22. http://dx.doi.org/10.1007/bf00665921.

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Xie, Taiping, Jiao Hu, Jun Yang, Chenglun Liu, Longjun Xu, Jiankang Wang, Yuan Peng, Songli Liu, Xiuyu Yin, and Yuanzhen Lu. "Visible-Light-Driven Photocatalytic Activity of Magnetic BiOBr/SrFe12O19 Nanosheets." Nanomaterials 9, no. 5 (May 13, 2019): 735. http://dx.doi.org/10.3390/nano9050735.

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Magnetic BiOBr/SrFe12O19 nanosheets were successfully synthesized using the hydrothermal method. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and UV-visible diffused reflectance spectra (UV-DRS), and the magnetic properties were tested using a vibration sample magnetometer (VSM). The as-produced composite with an irregular flaky-shaped aggregate possesses a good anti-demagnetization ability (Hc = 861.04 G) and a high photocatalytic efficiency. Under visible light (λ > 420 nm) and UV light-emitting diode (LED) irradiation, the photodegradation rates of Rhodamine B (RhB) using BiOBr/SrFe12O19 (5 wt %) (BOB/SFO-5) after 30 min of reaction were 97% and 98%, respectively, which were higher than that using BiOBr (87%). The degradation rate of RhB using the recovered BiOBr/5 wt % SrFe12O19 (marked as BOB/SFO-5) was still more than 85% in the fifth cycle, indicating the high stability of the composite catalyst. Meanwhile, after five cycles, the magnetic properties were still as stable as before. The radical-capture experiments proved that superoxide radicals and holes were main active species in the photocatalytic degradation of RhB.
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25

Menushenkov, Vladimir P., A. G. Savchenko, and Yurii D. Yagodkin. "Structure and Magnetic Properties of Hard Magnetic Nanocrystalline Oxide-Based Alloys." Solid State Phenomena 190 (June 2012): 247–50. http://dx.doi.org/10.4028/www.scientific.net/ssp.190.247.

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The structure and properties of SrFe12O19 powders, which were produced by mechanical activation followed by annealing and had a nanocrystalline structure, were studied. The powders prepared exhibit a high coercive force μ0Hci=0.40-0.45 Т. The substantially higher coercive force (up to 0.75-0.82 T) was typical to SrFe12O19 powders produced by oxide-glass crystallization. Nanostructured materials comprising Fe3O4 and Fe phases with crystallite sizes of 10-30 nm are shown can be prepared from Fe2O3+Fe, Fe2O3+Fe+Co and FeO+Co powder mixtures by mechanochemical technique followed by annealing. These nanomaterials have the hard magnetic properties and their coercive force reaches μ0Hci 0. 08 T.
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26

Natali, Marco, Sergio Tamburini, Roberta Bertani, Daniele Desideri, Mirto Mozzon, Daniele Pavarin, Federico Spizzo, Lucia Del Bianco, Federico Zorzi, and Paolo Sgarbossa. "Novel Magnetic Inorganic Composites: Synthesis and Characterization." Polymers 13, no. 8 (April 15, 2021): 1284. http://dx.doi.org/10.3390/polym13081284.

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The addition of magnetic particles to inorganic matrices can produce new composites exhibiting intriguing properties for practical applications. It has been previously reported that the addition of magnetite to concrete improves its mechanical properties and durability in terms of water and chloride ions absorption. Here we describe the preparation of novel magnetic geopolymers based on two different matrices (G1 without inert aggregates and G2 with inert quartz aggregates) containing commercial SrFe12O19 particles with two weight concentrations, 6% and 11%. The composites’ characterization, including chemical, structural, morphological, and mechanical determinations together with magnetic and electrical measurements, was carried out. The magnetic study revealed that, on average, the SrFe12O19 magnetic particles can be relatively well dispersed in the inorganic matrix. A substantial increase in the composite samples’ remanent magnetization was obtained by embedding in the geopolymer SrFe12O19 anisotropic particles at a high concentration under the action of an external magnetic field during the solidification process. The new composites exhibit good mechanical properties (as compressive strength), higher than those reported for high weight concretes bearing a similar content of magnetite. The impedance measurements indicate that the electrical resistance is mainly controlled by the matrix’s chemical composition and can be used to evaluate the geopolymerization degree.
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27

Palomino, R. L., A. M. Bolarín Miró, F. N. Tenorio, F. Sánchez De Jesús, C. A. Cortés Escobedo, and S. Ammar. "Sonochemical assisted synthesis of SrFe12O19 nanoparticles." Ultrasonics Sonochemistry 29 (March 2016): 470–75. http://dx.doi.org/10.1016/j.ultsonch.2015.10.023.

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28

Zhanyong, Wang, Zhong Liuming, Lv Jieli, Qian Huichun, Zheng Yuli, Fang Yongzheng, Jin Minglin, and Xu Jiayue. "Microwave-assisted synthesis of SrFe12O19 hexaferrites." Journal of Magnetism and Magnetic Materials 322, no. 18 (September 2010): 2782–85. http://dx.doi.org/10.1016/j.jmmm.2010.04.027.

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29

Obradors, X., X. Solans, A. Collomb, D. Samaras, J. Rodriguez, M. Pernet, and M. Font-Altaba. "Crystal structure of strontium hexaferrite SrFe12O19." Journal of Solid State Chemistry 72, no. 2 (February 1988): 218–24. http://dx.doi.org/10.1016/0022-4596(88)90025-4.

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30

Tan, Guolong, Yao Huang, and Haohao Sheng. "Magnetoelectric Response in Multiferroic SrFe12O19 Ceramics." PLOS ONE 11, no. 12 (December 9, 2016): e0167084. http://dx.doi.org/10.1371/journal.pone.0167084.

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31

Faloh-Gandarilla, Jael Cristina, Sergio Díaz-Castañón, and Bernard Enrico Watts. "Magnetization reversal and interactions in SrFe12O19." physica status solidi (b) 254, no. 4 (October 24, 2016): 1600393. http://dx.doi.org/10.1002/pssb.201600393.

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32

Feng, Shuangjiu, Jiangli Ni, Feng Hu, Xucai Kan, Qingrong Lv, and Xiansong Liu. "Hysteresis loss reduction in self-bias FeSi/SrFe12O19 soft magnetic composites." Chinese Physics B 31, no. 2 (February 1, 2021): 027503. http://dx.doi.org/10.1088/1674-1056/ac2d1a.

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The magnetic field provided by magnetized SrFe12O19 particles in FeSi/SrFe12O19 composites is used to replace the applied transverse magnetic field, which successfully reduces the magnetic loss of the composites with minor reduction of permeability. This magnetic loss reduction mainly comes from the decrease in hysteresis loss, while the eddy current loss is basically unaffected. The hysteresis loss reduction in magnetized composites is believed to be due to the decrease in domain wall displacement caused by the increase in the average magnetic domain size in a DC magnetic field. This is an effective method for reducing the magnetic loss of soft magnetic composites with wide application potential, and there is no problem of increasing the cost and the volume of the magnetic cores.
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33

Asghari, Mahboubeh, Ali Ghasemi, Ebrahim Paimozd, and Akimitsu Morisako. "Evaluation of microwave and magnetic properties of substituted SrFe12O19 and substituted SrFe12O19/multi-walled carbon nanotubes nanocomposites." Materials Chemistry and Physics 143, no. 1 (December 2013): 161–66. http://dx.doi.org/10.1016/j.matchemphys.2013.08.045.

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34

Liu, Bo, Shengen Zhang, Britt-Marie Steenari, and Christian Ekberg. "Controlling the Composition and Magnetic Properties of Nano-SrFe12O19 Powder Synthesized from Oily Cold Mill Sludge by the Citrate Precursor Method." Materials 12, no. 8 (April 16, 2019): 1250. http://dx.doi.org/10.3390/ma12081250.

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This paper proposes a new method for producing nano-SrFe12O19 powder by the citrate precursor route using solid waste as a source of iron. This solid iron-containing waste, which exists in the form of an oily sludge, is produced by a cold rolling mill. This sludge was first subjected to a process, including sulfuric acid leaching, oxidation, precipitation, and nitric acid leaching, to obtain an iron nitrate (Fe(NO3)3) solution. Next, the Fe(NO3)3 solution was mixed with a strontium nitrate (Sr(NO3)2) solution obtained by subjecting strontium carbonate to nitric acid leaching. Subsequently, citric acid, as chelating agent, and ammonia water, as precipitating agent, were added to the mixed solution to form a gel. The gel was dried and spontaneously combusted, then annealed at different temperatures for 2 h in flowing air. The effects of the Fe3+/Sr2+ molar ratio and annealing temperature on the formation, morphology, and magnetic properties of SrFe12O19 were investigated. The results showed that single-phase SrFe12O19 powder was obtained by decreasing the Fe3+/Sr2+ molar ratio from the stoichiometric value of 12 to 11.6 and increasing the annealing temperature to 1000 °C for 2 h. Adjustment of the Fe/Sr molar ratio to 12 and the annealing temperature to 900 °C enabled the magnetic properties to be optimized, including saturation magnetization (Ms) 80.2 emu/g, remanence magnetization (Mr) 39.8 emu/g, and coercive force (Hc) 6318 Oe.
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35

Ziemann, Sarah J., Nathan A. Fischer, Jimmy Lu, Thomas J. Lee, Michael Ennis, Thomas A. Höft, and Brittany Nelson-Cheeseman. "Hard magnetic elastomers incorporating magnetic annealing and soft magnetic particulate for fused deposition modeling." AIP Advances 12, no. 11 (November 1, 2022): 115305. http://dx.doi.org/10.1063/5.0119669.

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Magnetic elastomers with hard or permanent magnetic particulate are able to achieve complex motion not possible from soft magnetic elastomers. Magnetic annealing and fused deposition modeling (FDM) have been used to increase the performance of magnetic composites. This research explores how the magnetoactive properties of hard magnetic elastomers are influenced by magnetic annealing and the addition of the soft magnetic particulate. Three compositions of the thermoplastic magnetic elastomer composite are explored: 15 vol. % SrFe12O19, 10 vol. % SrFe12O19/5 vol. % carbonyl iron, and 5 vol. % SrFe12O19/10 vol. % carbonyl iron. The material is then extruded into FDM filaments. During the extrusion process, some filament is magnetically annealed in an axial applied field. Magnetic hysteresis loops show that the saturation magnetization and coercivity change based on the relative amount of hard and soft magnetic particulate. The presence of only one coercive field indicates magnetic coupling between the hard and soft components. Magnetoactive testing measures each sample’s mechanical deflection angle as a function of transverse applied magnetic field strength. Qualitative and quantitative results reveal that magnetic annealing is critical to the magnetoactive performance of the hard magnetic elastomers. The results also demonstrate that magnetic annealing and increased carbonyl iron both improve the magnetoactive deflection angle for a given applied field. Scanning electron microscopy shows a stratification effect in a range of the filaments. Understanding these hard magnetic elastomers provides insight into how performance can be controlled and optimized by magnetic annealing and combining hard and soft magnetic particulate.
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36

Manika, Georgia C., Sevasti Gioti, Aikaterini Sanida, Georgios N. Mathioudakis, Anxhela Abazi, Thanassis Speliotis, Anastasios C. Patsidis, and Georgios C. Psarras. "Multifunctional Performance of Hybrid SrFe12O19/BaTiO3/Epoxy Resin Nanocomposites." Polymers 14, no. 22 (November 9, 2022): 4817. http://dx.doi.org/10.3390/polym14224817.

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Polymer matrix nanocomposites are widely studied because of the versatility of their physical and mechanical properties. When these properties are present simultaneously, responding at relative stimuli, multifunctional performance is achieved. In this study, hybrid nanocomposites of SrFe12O19 and BaTiO3 ceramic particles dispersed in an epoxy resin matrix were fabricated and characterized. The content of SrFe12O19 was varying, while the amount of BaTiO3 was kept constant. The successful fabrication of the nanocomposites and the fine dispersion of the ceramic particles was verified via the morphological and structural characterization carried out with X-ray Diffraction patterns and Scanning Electron Microscopy images. Dielectric response and related relaxation phenomena were studied by means of Broadband Dielectric Spectroscopy. Dielectric permittivity augments with filler content, while the recorded relaxations, with descending relaxation time, are: (i) interfacial polarization, (ii) glass-to-rubber transition, (iii) intermediate dipolar effect, and (iv) re-orientation of polar-side groups of the main polymer chain. SrFe12O19 nanoparticles induce magnetic properties to the nanocomposites, which alter with the magnetic filler content. Static and dynamic mechanical response improves with filler content. Thermogravimetric analysis shown that ceramic particles are beneficial to the nanocomposites’ thermal stability. Glass transition temperature, determined via Differential Scanning Calorimetry, was found to slightly vary with filler content, in accordance with the results from dynamic mechanical and dielectric analysis, indicating the effect of interactions occurring between the constituents. Examined systems are suitable for energy storing/retrieving.
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37

Dahal, Jiba Nath, Dipesh Neupane, and Sanjay R. Mishra. "Exchange-Coupling Behavior in SrFe12O19/La0.7Sr0.3MnO3 Nanocomposites." Ceramics 2, no. 1 (February 8, 2019): 100–111. http://dx.doi.org/10.3390/ceramics2010010.

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Magnetically hard-soft (100-x) SrFe12O19–x wt % La0.7Sr0.3MnO3 nanocomposites were synthesized via a one-pot auto-combustion technique using nitrate salts followed by heat treatment in air at 950 °C. X-ray diffraction (XRD), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM) were used to characterize the structural and magnetic properties of the samples. XRD spectra revealed the formation of a mixture of ferrite and magnetite phases without any trace of secondary phases in the composite. Microstructural images show the proximity grain growth of both phases. The room temperature hysteresis loops of the samples showed the presence of exchange-coupling between the hard and soft phases of the composite. Although saturation magnetization reduced by 41%, the squareness ratio and coercivity of the nanocomposite improved significantly up to 6.6% and 81.7%, respectively, at x = 40 wt % soft phase content in the nanocomposite. The enhancement in squareness ratio and coercivity could be attributed to the effective exchange-coupling interaction, while the reduction in saturation magnetization could be explained on the basis of atomic intermixing between phases in the system. Overall, these composite particles exhibited magnetically single-phase behavior. The adopted synthesis method is low cost and rapid and results in pure crystalline nanocomposite powder. This simple method is a promising way to tailor and enhance the magnetic properties of oxide-based hard-soft magnetic nanocomposites.
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38

Sahoo, M. R., A. Barik, S. Kuila, S. Tiwary, and P. N. Vishwakarma. "Enhanced magnetoelectricity in bismuth substituted SrFe12O19 hexaferrite." Journal of Applied Physics 126, no. 7 (August 21, 2019): 074104. http://dx.doi.org/10.1063/1.5095979.

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39

Roy, Debangsu, and P. S. Anil Kumar. "Exchange spring behaviour in SrFe12O19-CoFe2O4 nanocomposites." AIP Advances 5, no. 7 (July 2015): 077137. http://dx.doi.org/10.1063/1.4927150.

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40

Martinez Garcia, R., V. Bilovol, L. M. Socolovsky, and K. Pirota. "Evidence of existence of metastable SrFe12O19 nanoparticles." Journal of Magnetism and Magnetic Materials 323, no. 23 (December 2011): 3022–26. http://dx.doi.org/10.1016/j.jmmm.2011.06.043.

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41

Asti, G., F. Bolzoni, J. M. Le Breton, M. Ghidini, A. Morel, M. Solzi, F. Kools, and P. Tenaud. "Magnetic anisotropy of LaCo-substituted SrFe12O19 ferrites." Journal of Magnetism and Magnetic Materials 272-276 (May 2004): E1845—E1846. http://dx.doi.org/10.1016/j.jmmm.2003.12.1275.

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42

Martinez Garcia, R., E. Reguera Ruiz, and E. Estevez Rams. "Structural characterization of low temperature synthesized SrFe12O19." Materials Letters 50, no. 2-3 (August 2001): 183–87. http://dx.doi.org/10.1016/s0167-577x(01)00222-1.

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43

Li, Qiao-ling, Yun Ye, De-xu Zhao, Wei Zhang, and Yan Zhang. "Preparation and characterization of CNTs–SrFe12O19 composites." Journal of Alloys and Compounds 509, no. 5 (February 2011): 1777–80. http://dx.doi.org/10.1016/j.jallcom.2010.10.038.

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44

Sun, Rui, Xin Li, Ailin Xia, Shubing Su, and Chuangui Jin. "Hexagonal SrFe12O19 ferrite with high saturation magnetization." Ceramics International 44, no. 12 (August 2018): 13551–55. http://dx.doi.org/10.1016/j.ceramint.2018.04.187.

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45

Baykal, A., M. S. Toprak, Z. Durmus, and H. Sozeri. "Hydrothermal Synthesis of SrFe12O19 and Its Characterization." Journal of Superconductivity and Novel Magnetism 25, no. 6 (April 26, 2012): 2081–85. http://dx.doi.org/10.1007/s10948-012-1587-0.

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46

Baykal, A. "Solvothermal Synthesis of Pure SrFe12O19 Hexaferrite Nanoplatelets." Journal of Superconductivity and Novel Magnetism 27, no. 3 (September 21, 2013): 877–80. http://dx.doi.org/10.1007/s10948-013-2369-z.

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47

Shafiu, S., H. Sözeri, and A. Baykal. "Solvothermal Synthesis of SrFe12O19 Hexaferrites: Without Calcinations." Journal of Superconductivity and Novel Magnetism 27, no. 6 (January 30, 2014): 1593–98. http://dx.doi.org/10.1007/s10948-014-2490-7.

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48

Hwang, Tea-Yeon, Guk-Hwan An, Jeong-Ho Cho, Jongryoul Kim, and Yong-Ho Choa. "Effects of Different Salts on Salt-Assisted Ultrasonic Spray Pyrolysis (SA-USP) Calcination for the Synthesis of Strontium Ferrite." Journal of Nanoscience and Nanotechnology 15, no. 10 (October 1, 2015): 8062–69. http://dx.doi.org/10.1166/jnn.2015.11259.

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Strontium ferrite (hexaferrite), SrFe12O19, was successfully fabricated in sizes ranging from hundreds of nanometers to several micrometers by salt-assisted ultrasonic spray pyrolysis-calcination using different salt media. All samples were single phases of SrFe12O19 without the intermediate phase, α-Fe2O3, and their morphology was hexagonal. As calcination temperature increased, the size of as-calcined samples and saturation magnetization, Ms, increased while coercivity decreased. The particle size of the obtained nanoparticles varied depending on the salt media and calcination temperatures. The best magnetic properties obtained in this experiment were a coercivity of 6973 Oe with a saturation magnetization of 68.3 emu/g. To the best of our knowledge, these coercivity values are the highest ever obtained. We propose a detailed mechanism explaining the growth of these particles and conclude that the resulting single-domain particle size is about 70 nm, taking into account of factors affecting coercivity in ferrite nano- to micro-sized particles.
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49

Hessien, Mahmoud M., Ali Omar Turky, Abdullah K. Alanazi, Mohammed Alsawat, Mohamed H. H. Mahmoud, Nader El-Bagoury, and Mohamed M. Rashad. "Boost the Crystal Installation and Magnetic Features of Cobalt Ferrite/M-Type Strontium Ferrite Nanocomposites Double Substituted by La3+ and Sm3+ Ions (2CoFe2O4/SrFe12−2xSmxLaxO19)." Materials 14, no. 24 (December 17, 2021): 7820. http://dx.doi.org/10.3390/ma14247820.

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Spinel cobalt ferrite/hexagonal strontium hexaferrite (2CoFe2O4/SrFe12−2xSmxLaxO19; x = 0.2, 0.5, 1.0, 1.5) nanocomposites were fabricated using the tartaric acid precursor pathway, and the effects of La3+–Sm3+ double substitution on the formation, structure, and magnetic properties of CoFe2O4/SrFe12−2xSmxLaxO19 nanocomposite at different annealing temperatures were assayed through X-ray diffraction, scanning electron microscopy, and vibrating sample magnetometry. A pure 2CoFe2O4/SrFe12O19 nanocomposite was obtained from the tartrate precursor complex annealed at 1100 °C for 2 h. The substitution of Fe3+ ion by Sm3–+La3+ions promoted the formation of pure 2CoFe2O4/SrFe12O19 nanocomposite at 1100 °C. The positions and intensities of the strongest peaks of hexagonal ferrite changed after Sm3+–La3+ substitution at ≤1100 °C. In addition, samples with an Sm3+–La3+ ratio of ≥1.0 annealed at 1200 °C for 2 h showed diffraction peaks for lanthanum cobalt oxide (La3Co3O8; dominant phase) and samarium ferrite (SmFeO3). The crystallite size range at all constituent phases was in the nanocrystalline range, from 39.4 nm to 122.4 nm. The average crystallite size of SrFe12O19 phase increased with the number of Sm3+–La3+ substitutions, whereas that of CoFe2O4 phase decreased with an x of up to 0.5. La–Sm co-doped ion substitution increased the saturation magnetization (Ms) value and the subrogated ratio to 0.2, and the Ms value decreased with the increasing number of double substitutions. A high saturation magnetization value (Ms = 69.6 emu/g) was obtained using a La3+–Sm3+ co-doped ratio of 0.2 at 1200 for 2 h, and a high coercive force value (Hc = 1192.0 Oe) was acquired using the same ratio at 1000 °C.
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50

Wei, Yanhui, Mingyue Liu, Jiaxing Wang, Guochang Li, Chuncheng Hao, and Qingquan Lei. "Effect of Semi-Conductive Layer Modified by Magnetic Particle SrFe12O19 on Charge Injection Characteristics of HVDC Cable." Polymers 11, no. 8 (August 5, 2019): 1309. http://dx.doi.org/10.3390/polym11081309.

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For high voltage direct current (HVDC) cable, a semi-conductive layer lies between the conductor and the insulation layer; as the charge migrates the path from the conductor to the insulation material, it will affect space charge injection. In this work, the research idea of changing the injection path of moving charges within semi-conductive layer by magnetic particles was proposed. Semi-conductive composites with different SrFe12O19 contents of 1 wt.%, 5 wt.%, 10 wt.%, 20 wt.%, and 30 wt.% were prepared, and the amount of injected charges in the insulation sample was characterized by space charge distribution, polarization current, and thermally-stimulated depolarization current. The experimental results show that a small amount of SrFe12O19 can significantly reduce charge injection in the insulation sample, owing to the deflection of the charge migration path, and only part of the electrons can enter the insulation sample. When the content is 5 wt.%, the insulation sample has the smallest charge amount, 0.89 × 10−7 C, decreasing by 37%, and the steady-state current is 6.01 × 10−10 A, decreasing by 22%. When SrFe12O19 content exceeds 10 wt.%, the charge suppression effect is not obvious and even leads to the increase of charge amount in the insulation sample, owing to the secondary injection of charges. Most moving charges will deflect towards the horizontal direction and cannot direct access to the insulation sample, resulting in a large number of charges accumulation in the semi-conductive layer. These charges will seriously enhance the interface electric field near the insulation sample, leading to the secondary injection of charges, which are easier to inject into the insulation sample.
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