United States

As 5G technology moves higher into the microwave frequency regime, the risk of coupling EM energy into susceptible electronic circuits grows. Minimizing this interference is driving the need for compact, lightweight broadband absorbers to protect sensitive and high precision electronics. Manganese zinc ferrite (Mn1-xZnxFe2O4) microparticles have previously been demonstrated to be magnetically lossy up to 10 GHz, the desired frequency regime, and have the potential to meet the energy density and attenuation performance needs [1, 2]. However, optimizing the shielding effectiveness requires improved understanding of Mn1-xZnx stoichiometry and the dominant dielectric and magnetic absorption mechanisms for each stoichiometry. This presentation discusses results, up to 20 GHz, from experimentally investigating the shielding effectiveness and quality factor attenuation of Mn1-xZnxFe2O4 with a mean particle size of 30 microns, loaded to 50 volume percent in epoxy, and variation in x values from 0 to 1 in intervals of 0.1. Complex permeability and permittivity measurements were conducted to identify the absorption mechanism. An increase in absorption was observed in Mn1-xZnxFe2O4 for x=0.3 and 0.4 compared with other stoichiometries. A likely explanation of the observed increase is provided [3].&lt;br&gt;
**References:**&lt;br&gt;[1] T. Tsutaoka, Journal of Applied Physics 93, 2789 (2003); https://doi.org/10.1063/1.1542651&lt;br&gt;
[2] R. Dosoudil, M. Usakova, J. Franek, J. Slama and A. Gruskova, &quot;Particle Size and Concentration Effect on Permeability and EM-Wave Absorption Properties of Hybrid Ferrite Polymer Composites,&quot; in IEEE Transactions on Magnetics, vol. 46, no. 2, pp. 436-439, Feb. 2010, doi: 10.1109/TMAG.2009.2033347.&lt;br&gt;
[3] This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy?s National Nuclear Security Administration under contract DE-NA0003525.&lt;br&gt;



MMM 2022

The Role of Stoichiometry in Mn1 xZnx Ferrite Microwave Absorbers

As 5G technology moves higher into the microwave frequency regime, the risk of coupling EM energy into susceptible electronic circuits grows. Minimizing this interference is driving the need for compact, lightweight broadband absorbers to protect sensitive and high precision electronics. Manganese zinc ferrite (Mn1-xZnxFe2O4) microparticles have previously been demonstrated to be magnetically lossy up to 10 GHz, the desired frequency regime, and have the potential to meet the energy density and attenuation performance needs [1, 2]. However, optimizing the shielding effectiveness requires improved understanding of Mn1-xZnx stoichiometry and the dominant dielectric and magnetic absorption mechanisms for each stoichiometry. This presentation discusses results, up to 20 GHz, from experimentally investigating the shielding effectiveness and quality factor attenuation of Mn1-xZnxFe2O4 with a mean particle size of 30 microns, loaded to 50 volume percent in epoxy, and variation in x values from 0 to 1 in intervals of 0.1. Complex permeability and permittivity measurements were conducted to identify the absorption mechanism. An increase in absorption was observed in Mn1-xZnxFe2O4 for x=0.3 and 0.4 compared with other stoichiometries. A likely explanation of the observed increase is provided [3]. 
**References:** [1] T. Tsutaoka, Journal of Applied Physics 93, 2789 (2003); https://doi.org/10.1063/1.1542651 
[2] R. Dosoudil, M. Usakova, J. Franek, J. Slama and A. Gruskova, "Particle Size and Concentration Effect on Permeability and EM-Wave Absorption Properties of Hybrid Ferrite Polymer Composites," in IEEE Transactions on Magnetics, vol. 46, no. 2, pp. 436-439, Feb. 2010, doi: 10.1109/TMAG.2009.2033347. 
[3] This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy?s National Nuclear Security Administration under contract DE-NA0003525.

poster

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In the present work, the effect of crystallite size on the magnetic properties of nanocrystalline FeCo2O4, synthesized by co-precipitation technique, has been studied. The as synthesized sample has been annealed at 500 , 900 & 1000 to vary the crystallite size. The XRD results confirm the presence of single cubic phase in all the annealed samples and increase in the crystallite size with the increasing annealing temperature. FESEM images show the spherical morphology of prepared nanoparticles which become irregular in shape as temperature increases and particle size also increases with increasing annealing temperature. XPS analysis confirms the mixed oxidation states of Fe with Fe+2 and Fe+3, Co with Co+2 and Co+3. The temperature dependence magnetization (M-T curves) and field dependence magnetization (M-H curves) at different temperatures have been measured using Quantum design MPMS3 SQUID magnetometer. The low temperature M-H curves show the presence of metamagnetic phase transition in the samples annealed at 900 oC and 1000 oC. This possibly occurs due to the co-existence of ferromagnetic and antiferromagnetic phases in the synthesized samples. The coexistence of AFM and FM phases may be attributed to spin canting/surface spin disorder in nanocrystalline magnetic nanoparticles. Furthermore, the samples annealed at higher temperature show strong ferromagnetism, higher saturation magnetization, higher coercivity and remanence. Moreover, the M-H curves, measured below 100 K, of the samples annealed at 500 oC and 900 oC show jumps in the magnetization value at certain magnetic fields (see Fig. 1). The detail correlation between structural and observed magnetic properties will be described and discussed in this paper. 
**References:** 

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Study of crystallite size on magnetic properties of nanocrystalline FeCo2O4

With 10 million deaths in 2020 cancer remains one of the most challenging diseases in contemporary medicine. Chemotherapy, surgery, and radiation therapy are commonly used to treat cancer. These treatments severely harm healthy tissues and succeed rarely in advance stages of disease. Recent studies indicate that magnetic hyperthermia, which involves targeted delivery of magnetic nanoparticles to tumor cells followed by localised remote heating of cancer tissues could revolutionise clinical practice in the treatment of cancer, either as standalone intervention or adjunct to radiotherapy and chemotherapy. Water dispersible magnetic nanoparticles (MNPs) of ferrites (AFe2O4; A=Fe, Mn, Co) are the promising candidates for magnetic hyperthermia due to their high chemical stability, biocompatibility, moderate magnetization and high specific absorption rates (SAR). In this article, we have evaluated magnetic hyperthermia efficiency of water based magnetic fluids of AFe2O4 nanoparticles. AFe2O4 nanoparticles were synthesized by chemical co-precipitation method. Nanoparticles were coated with a bilayer of oleic acid and dispersed in water. MNPs concentrations in magnetic fluids were 70 mg/mL for Fe3O4, 200 mg/mL for MnFe2O4 and 60 mg/mL for CoFe2O4. Structural and magnetic properties of MNPs were investigated by X-Ray diffraction (XRD) and vibrating sample magnetometer (VSM), respectively. XRD study revealed that AFe2O4 NPs exhibits cubic inverse spinel structure. Fe3O4 (Ms = 48 emu/g, Mr = 2.60 emu/g, Hc = 49 Oe), MnFe2O4 (Ms = 40 emu/g, Mr = 2.60 emu/g, Hc = 35 Oe) and CoFe2O4 (44 emu/g, Mr = 10.10 emu/g, Hc =440 Oe) NPs exhibits soft ferromagnetic behaviour. Magnetic hyperthermia measurements were performed as a function of magnetic field strength (2-10 mT) and field frequency (162-935.6 kHz) for 10 minutes. MNPs exhibits highest SAR values for 10 mT field strength at 935.6 kHz. Amongst the tested MNPs, Fe3O4 has the highest SAR value (27.35 W/g), followed by MnFe2O4 (1.91 W/g) and CoFe2O4 (0.94 W/g). Considering this, it is concluded that amongst the inverse spinel ferrite nanostructures AFe2O4 (A=Fe, Mn, Co), Fe3O4 nanoparticles are most suitable for magnetic fluid hyperthermia applications. 
**References:** 

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Magnetic Hyperthermia of AFe2O4 (A=Fe, Mn, Co) Nanoparticles Prepared by Co precipitation Method.

The rare-earth iron garnets R3Fe5O12 are important magnetic materials due to their ferrimagnetic property above room temperature. Some of them are potential candidate materials in magnetic refrigeration, which works on the magnetocaloric effect (MCE). Researchers have focused on improving the magnetic entropy change along with these garnet’s relative cooling power (RCP), primarily via doping strategies. This study reports the structural, magnetic, and magnetocaloric effect in Cr-doped Gd3Fe5-x CrxO12 garnet. The powder samples with a composition of Gd3-xRExFe5O12 ( x=0.0,0.1,0.2,0.25 and 0.3) were prepared via facile autocombustion method followed by an annealing process. The phase and structural properties obtained by using x-ray diffraction show samples are single-phase with cubic Ia3dsymmetry. The lattice parameter and cell volume decreased upon Cr3+ substitution because of the preferential occupation of smaller Cr3+ (0.615A) ions at the octahedral site of Fe3+ (0.645A) ions. All Cr3+ doped samples showed paramagnetic behavior at RT and ferromagnetic behavior at 6 K. The isothermal magnetic entropy changes, -ΔSM, was derived from the magnetic isotherms in a field up to 5T. The maximum magnetic entropy change, increased with Cr3+ substitution. The Cr3+ doped Gd3Fe4.75Cr0.25O12 sample exhibit a maximum value of (3.87 J kg-1K-1 ) which is ~ 1.8% higher than Gd3Fe5O12 (3.8 J kg-1K-1) sample. While the maximum relative cooling power value of 412 J kg-1 was measured for the x = 0.25 sample, which is ~ 6 % higher than Gd3Fe5O12 (389 J kg-1) sample. These values are relatively high and comparable to some noticeable magnetocaloric materials. The observed magnetic changes are ascribed to altered Fe-O-Fe bond angle and bond distances. Thus, based on these results, our samples are promising materials for magnetic refrigeration technology. 
**References:**

Structural, Magnetic and Magnetocaloric study of Cr doped Gd3Fe5 x CrxO12, (0.0 ≤ x ≤ 0.3)

Abstract Link: https://www.mrs.org/meetings-events/fall-meetings-exhibits/2023-mrs-fall-meeting/symposium-sessions/presentations/detail/2023_mrs_fall_meeting/2023_mrs_fall_meeting-3953941 

Rare-earth chromites (RCrO3) are an important sub-class of functional materials with interesting magnetic and magnetocaloric properties. These materials are a promising candidate for magnetic refrigeration applications as the Ho3+ ion owns a large magnetic moment of ~ 10.61μB. This study reports synthesis and magnetocaloric effect in rare-earth and aluminum-doped polycrystalline HoCrO3, Ho0.67Tm 0.33CrO3, and Ho0.67Gd0.33CrO3 orthochromites. The samples were synthesized via the facile sol-gel autocombustion method. The pure orthorhombic phases with space group Pnma have been confirmed by X-ray diffraction. The lattice parameter of the samples was calculated from the XRD pattern refinement. The lattice parameters and volume decreased with the Al3+ substitution as the ionic radius of Al3+ (0.535 A) is smaller than Cr3+ (0.615A). In addition, the FTIR spectroscopy confirmed the formation of the Ho–O bond, and Cr–O, and Cr–Cr bonds in all samples. Raman's study confirmed the stretching vibration mode of CrO6 octahedra near 580 cm-1. The magnetic measurement of compounds showed that the samples exhibit a transition below 20 K. Enhanced magnetization and increased magnetic entropy change, () from 6.50 J kg-1K-1 (HoCrO3 ) to 8.25 Jkg-1K-1 (HoCr0.5Al0.5O3) was observed in the field up to 5T. A variation in maximum entropy changes and relative cooling power is observed to be dependent on Al3+ substitution in the studied chromites which are related to changes in Cr3+-Cr3+ exchange coupling resulting from changes in the Cr1-O1-Cr1 bond angle and Cr1-O1 bond lengths respectively. To our knowledge, Al3+ doped HoCrO3 has not been reported in the literature. The studied Al3+ doped chromites have potential low-temperature magnetic refrigeration application. 
**References:**

Structural, Magnetic, and Magnetocaloric effect in Al doped HoCrO3.

Microwave absorbers are increasingly being used to enhance shielding performance at higher frequencies. Great effort has been made to develop materials with superior reflection loss (RL), thin thickness, wide bandwidth, and low density to improve their efficiency in electromagnetic microwave absorption. However, for the magnetic absorbing materials, the higher complex permittivity makes the impedance matching effect poorer, and it is hard to obtain a better microwave absorption. In this work, the rare-earth intermetallics La2Fe4Co10B fine powders with planar magnetocrystalline anisotropy and high magnetization were prepared using the hydrogenation desorption (HD) technique. By annealing the obtained magnetic powders at different temperatures in the air to slowly form an oxide layer on their surfaces, its complex permittivity can be significantly reduced without changing its complex permeability, and its microwave absorption can be dramatically enhanced. For the La2Fe4Co10B/paraffin composite, the real part of the complex permittivity at 10 GHz can be reduced from 18.0 to 8.4, with a decreasing range of 53.3%. The reflection loss (RL) is -25.4 dB at 1.6 mm with an effective absorption bandwidth of 6.2 GHz. As an efficient and lightweight absorber, La2Fe4Co10B/paraffin composite has potential application value in constructing new microwave absorber. 
**References:** 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/98aaafb875087b2de284a938af3c0e07.png) 
Fig.1. Frequency dependence of electromagnetic parameters of La2Fe4Co10B/paraffin composites with different annealing temperatures: (a) the complex permittivity; (c) the complex permeability. 
![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/9877d6aa4016791ac0c42b0785c8fa26.png) 
Fig.2. The RL curves with the broadest effective absorption bandwidth of La2Fe4Co10B/paraffin composites with different annealing temperatures.

Effect of Oxidation on the Microwave Absorption Properties of Rare earth Intermetallics La2Fe4Co10B

Investigations and quality improvement of structural steels with high resistance to impact loading, used for automobile parts, are critically important because of minimizing passenger's injuries during a crash. Extensive microstructural investigations revealed that high-strain-rate deformation under impact loading leads to the formation of hard and narrow adiabatic shear band in a soft matrix [1]. The formation of such inhomogeneous microstructure results from excessive thermal softening and thermo-viscous instability, leading to strain localization. Despite the recent growing understanding of the formation mechanism, effects on physical properties were not understood because of few reports available. Here, we report results of measurements of magnetic first-order-reversal curves (FORCs) for high-strain rate deformed steels for the possible application to non-destructive evaluation (NDE) of inhomogeneous microstructural changes. FORCs are one kind of asymmetrical minor loops and provide useful information on interaction field (Hu) and coercivity (Hc) distribution, which can not be obtained from conventional major hysteresis loop. 
Cylindrical samples of high-tensile AISI4340 steels were subjected to high-strain-rate deformation using a split Hopkinson pressure bar. We prepared samples with different strain rates up to 4500 s-1. FORCs were measured at room temperature using a SQUID magnetometer. Figure 1(a) and 1(b) show FORC diagrams after high-strain rate deformation with a strain rate of 1800 and 4500 s-1, respectively. In addition to a large FORC distribution peak which extends along Hu direction (peak 1), we found that a small additional peak appears at Hc~400 Oe (peak 2 in Fig.1), whose position gradually shifts toward a higher Hc with increasing strain rate. This indicates that a small fraction of magnetically hard regions (i.e. adiabatic shear bands) are formed in a soft matrix and the regions become magnetically harder at higher strain rate. These observations clearly demonstrate that FORCs can be a useful technique of investigating inhomogeneous microstructures under impact loading. 
**References:** [1] A. G. Odeshi, M. N. Basim, et al., J. Mater. Proc. Tech. vol.169 (2005) 150. 
[2] B.C. Dodrill, J. Lindemuth, C. Radu, H. Reichard, MRS Bulletin vol.40 (2015) 903. 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/92b10b850b165bf6b78860980bcb57dd.png) 
Fig. 1 FORC diagram after high-strain rate deformation with a strain rate (SR) of (a) 1800 and (b) 4500 s-1.

First order

In recent years, the driving frequency of electric equipment has increased, and we need to reduce eddy current loss to apply typical metallic soft magnetic materials into high-frequency driving equipment. As a practical method to reduce the loss is a reduction in the thickness, we recently reported a fabrication process of Fe-Ni thin films (< 10 μm) using an electroless plating method [1]. Although many reports for electroless deposited Fe-Ni films, as well as ours, employed conductive substrates [2-3], the conductive substrates are not suitable since eddy current also flows in the substrates. We, therefore, focused on the polyimide (PI) used as a non-conductive substrate and investigated a fabrication process of Fe-Ni films using the PI substrate. 
Since the PI does not have catalytic activity for the deposition of Fe-Ni films, we investigated a chemical metallization process of PI [4]. First, we immersed the PI sheet in a KOH solution and then in an AgNO3 one. By these immersions, the PI sheet obtains catalytic activity. The details of our electroless plating process are described in Ref. [1]. 
To obtain suitable conditions for the metallization of the PI surface, we investigated the effect of immersion time in KOH and AgNO3 on the film thickness. Figure 1 shows the thickness as a function of the immersion time in each solution. The thickness slightly increased with increasing the immersion time in AgNO3, and we observed the correlation between thickness and the immersion time in KOH, implying that the immersion time in KOH is more important than that for AgNO3. 
Figure 2 shows the coercivity of the films as a function of thickness. We changed the thickness by adjusting the DMAB concentration or the deposition time. In our experimental conditions, the coercivity increased with increasing the thickness due to an increase in the roughness, and the value of coercivity was almost the same as previously reported ones (Hc =30-96 A/m) using conductive substrates [1-3.5]. We, therefore, concluded that the Fe-Ni films with low coercivity could be obtained by the optical metallization of the PI surface. 
**References:** [1] T. Yanai et al., AIP Advances, Vol.10 ,#015047 (2020) 
[2] R. Anthony et al., Applied Surface Science, Vol.357 , pp.385-390 (2015) 
[3] M. Takai et al., IEICTE Trans. Electron., Vol.E78-C , pp. 1530-1535 (1995) 
[4] G. Stéphane et al., Applied surface science, Vol.307, pp.716-723 (2014) 
[5] T. Yokoshima et al., Journal of Electroanalytical Chemistry, Vol.491 , pp.197-202 (2000) 

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Magnetic properties of Fe Ni films deposited on a non

In recent years, metallic soft magnetic materials, which can be used at high frequency, have been strongly required due to the development of power electronics techniques. When driving the metallic materials at a high frequency, we need to reduce the thickness or control the magnetization process (the anisotropy) to reduce eddy current loss. In the present study, we focused on an electroplating method to prepare thin ribbons and a bilayer structure to control the direction of anisotropy using the magnet elastic effect.
To construct a bilayer structure, we firstly electroplated 8 μm-thick Fe6Ni94 films on a stainless substrate and then electroplated 8 μm-thick Fe56Ni44 films. The plating bath and conditions were almost the same as ref [1]. Figure 1 shows a schematic representation of the electroplating, and we prepared 140 mm-long bilayer films. After electroplating, the bilayer film was peeled off from the substrate. The ribbon (peeled film) formed into a toroidal core (D = 10 mm).
Figure 2 shows the hysteresis loop of the core, and the difference between the loops is the inside layer. The blue and red loops are for the inside layer of Fe6Ni94 and Fe56Ni44, respectively. An obvious difference was observed between the two loops. It is well-known that the magnetostriction constant of Fe-Ni alloys depends on the composition. The sing of magnetostriction constant for Ni-rich phase such as Fe6Ni94 is negative, whereas Fe-rich one such as Fe56Ni44 is positive. When the ribbon formed a toroidal shape, bending stress is induced in the ribbon. The stress of the outer side and the inner one is tension and compression, respectively. In the case of the inside layer of Fe56Ni44, the directions of the induced anisotropy are perpendicular to the ribbon axis for both phases, indicating that the easy axis is perpendicular to the ribbon axis. Consequently, the permeability and the hysteresis loss decrease. As the perpendicular anisotropy is effective in reducing the eddy current loss, we found that thin bilayer ribbons, which consist of two phases with positive and negative magnetostriction, are an attractive structure for high-frequency applications. 
**References:** [1]T. Yanai, J. Kaji, K. Koda, K. Takashima, M. Nakano, H. Fukunaga, “Magnetic Properties of Exchange-Coupled Fe-Ni/Fe22Ni78 Double-Layered Thick Films”, IEEE Transactions on Magnetics, 54 (2018) #2002503. 

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Soft magnetic bilayer thin ribbons prepared using an electroplating method

With the development of the 5G applications, micrometer and millimeter microwaves have been full filling the space around people. They not only interfere with tons of electronic devices but damage human health as well. To combat these problems, there is an urgent need for microwave absorption materials. However, most of the research on microwave absorption materials stays within the 2~18GHz frequency range, while the 5G millimeter microwave’s frequency can reach up to 24GHz or higher. Thus, more studies of microwave absorption properties in a higher frequency band are necessary. In this work, we report the microwave absorption properties of several soft magnetic composites in frequency up to 40GHz. Common materials such as iron, Y2Fe16Si, Ce2Fe17N3-δ, La2Fe4Co10B micron powders which experience excellent microwave absorption properties in 2~18GHz are included. Within 2~40GHz, the reflection loss(RL) of iron/paraffin, Y2Fe16Si/paraffin, Ce2Fe17N3-δ/paraffin and La2Fe4Co10B /paraffin composites could reach -46.2dB, -71.4dB, -49.1dB, and -49.0dB, respectively. And their effective absorption bandwidth(RL<-10dB) could reach 16.9GHz, 8.53GHz, 10.08GHz, and 7.4GHz, respectively. Though the measurements are extended to 40GHz, the RL of most of these materials could not maintain a low level at 40GHz, which is restricted by the cutoff frequencies of the materials. The measured data shows that these soft magnetic composites are good candidates for high-frequency microwave absorption materials, while exploring magnetic materials with further higher cutoff frequencies may result in a better performance. 
**References:** Hu, Q. W., Qiao, G. Y., Yang, W. Y. et al., J. Phys. D: Appl. Phys., Vol. 53, p.115001 (2020) 
Qiao, G. Y., Yang, W. Y., Lai, Y. F. et al., Mater. Res. Express., Vol. 6, p.016103 (2019) 
Zuo, W. L., Qiao, L., Chi, X. et al., J. Alloys Compd., Vol. 509, p.6359-6363 (2011) 

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/f708b4db425d125194f5d0dce657f7a5.png) 
Fig.1 The RL curves with the broadest effective absorption bandwidth of different composites. 
![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/b7d05a0b606f27825ea5543beca16e60.png) 
Fig.2 The RL curves with the minimum RL of different composites.

The microwave absorption properties of several soft magnetic materials in frequency up to 40GHz

Motor-driven systems are estimated to use over 40% of all global electricity consumption, giving rise to over 6 Gt of CO2 emissions [1]. To reduce the impact, motors should have higher efficiency. Electrical steels, Fe-Si which have low iron losses are commonly used as soft magnetic materials for motors but higher Bs materials have been desired for higher power density motors. It is well known that Fe-Co alloys have the highest Bs among bulk, stable materials. In fact, Permendur, 49Fe-49Co-2V (mass %) is already used in some high-performance motors, since it has a good soft magnetic properties. However, the drawbacks of Permendur are poor workability owing to the existence of a the brittle B2 phase (ordered phase) . In this study, we first conducted neutron diffraction measurements on the Fe-Co alloys with different Co contents to check the existence of the B2 phase in these alloys. And then, the effect of Si/Al addition on magnetic properties of 82Fe-18Co alloy was investigated in order to improve the soft magnetic properties.

Experimental Procedures 
Four samples with different Co contents (49Fe-49Co-2V, 73Fe-27Co, 82Fe-18Co, and 95Fe-5Co) were prepared through melting, casting, forging and annealing processes. The neutron diffraction study was conducted with iMATERIA spectrometer at the Materials and Life Sciences Facility at the J-PARC (Japan Proton Accelerator Research Complex). For the study of Si/Al addition, 0.2 mm-thick sheets with the addition of Si/Al in the range of 0~1.75 mass% were prepared by melting, casting process, followed by forging, annealing, hot and cold rolling processes. Magnetic properties were measured with a BH-tracer.

Results 
The result showed that 49Fe-49Co-2V and 73Fe-27Co alloys contained the B2 phase. On the other hand, 82Fe-18Co and the 95Fe-5Co did not contain B2, which suggests that these two alloys will likely to have good workability. Therefore, we chose 82Fe-18Co alloy for the investigation of Si/Al addition. Fig. 1 shows the soft magnetic properties of 82Fe-18Co with and without Si/Al addition. It was found that the small addition of Si/Al reduced the iron loss while maintaining high Bs. 
**References:** [1] Paul Waide & Conrad U. Brunner et al., IEA Energy Efficiency Series, Working Paper, 2011.

![](https://s3.eu-west-1.amazonaws.com/underline.prod/uploads/markdown_image/1/image/eeb054706cc0fdec4a252ed031c1061a.png) 
Fig. 1 Effect of Si and Al addition on the soft magnetic properties of Fe-18Co alloy

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