The combination of fabrication of a precursor and subsequent thermal treatments is an effective strategy for crafting multi-phase SmCo-based nanocomposite magnets. However, a comprehensive understanding of the effect of precursor state on the formation of multiphase magnets has yet to be fully explored. In this study, Sm(CoFeCuZr)/Fe(Co) of precursors were prepared via mechanical alloying. The precursor state was tailored by adjusting the ball milling process, as well as the content and composition of soft magnetic phase. The amorphization degree of the SmCo phase, the atomic ratio of Sm:Co in the SmCo alloy, and the content of Fe(Co) in the precursor increase with the increasing ball milling time, the increase in the content of the soft phase and the proportion of Fe within the soft phase. And this resulted in an increase in the content of Fe(Co) and SmCo3 phases but a decrease in the content of SmCo7 phase in samples annealed at 400–720 °C. This further led to an increase in the saturation magnetization and a decrease in the coercivity of the triphase (SmCo7 + SmCo3)/Fe(Co) magnet. The mechanisms responsible for the precursor state control and the formation of the triphase magnet were investigated.
结合前驱体的制造和随后的热处理是制作基于钐钴的多相纳米复合磁体的有效策略。然而，关于前驱体状态对多相磁体形成的影响的全面了解还有待充分探索。本研究通过机械合金化方法制备了 Sm(CoFeCuZr)/Fe(Co) 前驱体。通过调整球磨工艺以及软磁相的含量和成分，对前驱体状态进行了定制。钐钴相的非晶化程度、钐钴合金中 Sm:Co 的原子比以及前驱体中 Fe(Co) 的含量随着球磨时间的增加、软磁相含量的增加以及软磁相中 Fe 的比例的增加而增加。这导致在 400-720 °C 下退火的样品中，Fe(Co) 和 SmCo3 相的含量增加，但 SmCo7 相的含量减少。这进一步导致了三相（SmCo7 + SmCo3）/铁（Co）磁体饱和磁化率的增加和矫顽力的降低。我们研究了前驱体状态控制和三相磁体形成的机制。
{"title":"Effect of precursor state on the formation of triphase (SmCo7 + SmCo3)/Fe(Co) magnets","authors":"Jieqiong Gao, Xiaohong Li, Tiancong Li, Li Lou, Yingxin Hua, Jinyi Wang, Yiran Li, Defeng Guo","doi":"10.1016/j.jmmm.2024.172666","DOIUrl":"10.1016/j.jmmm.2024.172666","url":null,"abstract":"<div><div>The combination of fabrication of a precursor and subsequent thermal treatments is an effective strategy for crafting multi-phase SmCo-based nanocomposite magnets. However, a comprehensive understanding of the effect of precursor state on the formation of multiphase magnets has yet to be fully explored. In this study, Sm(CoFeCuZr)/Fe(Co) of precursors were prepared via mechanical alloying. The precursor state was tailored by adjusting the ball milling process, as well as the content and composition of soft magnetic phase. The amorphization degree of the SmCo phase, the atomic ratio of Sm:Co in the SmCo alloy, and the content of Fe(Co) in the precursor increase with the increasing ball milling time, the increase in the content of the soft phase and the proportion of Fe within the soft phase. And this resulted in an increase in the content of Fe(Co) and SmCo<sub>3</sub> phases but a decrease in the content of SmCo<sub>7</sub> phase in samples annealed at 400–720 °C. This further led to an increase in the saturation magnetization and a decrease in the coercivity of the triphase (SmCo<sub>7</sub> + SmCo<sub>3</sub>)/Fe(Co) magnet. The mechanisms responsible for the precursor state control and the formation of the triphase magnet were investigated.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172666"},"PeriodicalIF":2.5,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.jmmm.2024.172649
Yizhe Zhu, Yuchen Jin, Zewen Gu, Da Zhao, Jianlin Liu
Magnetically controlled micro-soft robots have been widely used in precise drug delivery and treatment of the gastrointestinal tract due to their advantages of high flexibility, environmental adaptability and non-contact control. Current micro-soft robots usually employ simple configurations and homogeneous materials, which limits their deformation and movement capacities. Therefore, it is of great significance to make a comprehensive investigation on the properties of key elastic structures of micro-soft robots with complex configurations. In the present work we conduct a systematic study on the design, preparation, experiments and simulations of the common disc-shaped robot and the proposed bio-inspired cobweb robot. Firstly, the topology optimization strategies are developed to design the configuration of the bio-inspired cobweb robot. Then, two kinds of robots are prepared by the mold manufacturing method of mixing NdFeB particles and silica gel solution in a certain proportion and pouring. Next, the magnetic control deformation experiments on these two kinds of robots are carried out, and the corresponding force-magnetic coupling model is established. The simulation and experimental results of the longitudinal and lateral displacement and the deflection on a specific path are compared and analyzed, which validates the accuracy of the simulation model. Finally, based on the developed numerical model, the effects of different residual magnetization and different magnet positions of the driving force of the cobweb structure are further predicted. The results indicate that the topologically optimized cobweb robot presents better deformation and movement capacities under the same size. These findings shed new light on engineering soft robots with complicated configurations and improved capacity than existing soft robots.
{"title":"A magnetically controlled bio-inspired cobweb soft robot based on structural topology optimization","authors":"Yizhe Zhu, Yuchen Jin, Zewen Gu, Da Zhao, Jianlin Liu","doi":"10.1016/j.jmmm.2024.172649","DOIUrl":"10.1016/j.jmmm.2024.172649","url":null,"abstract":"<div><div>Magnetically controlled micro-soft robots have been widely used in precise drug delivery and treatment of the gastrointestinal tract due to their advantages of high flexibility, environmental adaptability and non-contact control. Current micro-soft robots usually employ simple configurations and homogeneous materials, which limits their deformation and movement capacities. Therefore, it is of great significance to make a comprehensive investigation on the properties of key elastic structures of micro-soft robots with complex configurations. In the present work we conduct a systematic study on the design, preparation, experiments and simulations of the common disc-shaped robot and the proposed bio-inspired cobweb robot. Firstly, the topology optimization strategies are developed to design the configuration of the bio-inspired cobweb robot. Then, two kinds of robots are prepared by the mold manufacturing method of mixing NdFeB particles and silica gel solution in a certain proportion and pouring. Next, the magnetic control deformation experiments on these two kinds of robots are carried out, and the corresponding force-magnetic coupling model is established. The simulation and experimental results of the longitudinal and lateral displacement and the deflection on a specific path are compared and analyzed, which validates the accuracy of the simulation model. Finally, based on the developed numerical model, the effects of different residual magnetization and different magnet positions of the driving force of the cobweb structure are further predicted. The results indicate that the topologically optimized cobweb robot presents better deformation and movement capacities under the same size. These findings shed new light on engineering soft robots with complicated configurations and improved capacity than existing soft robots.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172649"},"PeriodicalIF":2.5,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-13DOI: 10.1016/j.jmmm.2024.172663
Donglin He , Liangrui Tan , Peng Wang , Zhibiao Xu , Qinglin Li , Tao Wang
Modern communications have created a great demand of magneto-dielectric functional materials having low loss and high permeability properties under the sub-6 GHz band. CoZn-18H planar hexagonal ferrites with strong magnetic anisotropy are more promising in meeting these requirements than that of traditional ferrites. The textured CoZn-18H hexagonal ferrites were synthesized by the reactive templated grain growth (RTGG) method to obtain high magnetic resonance frequency without sacrificing permeability. The layered texture composed of flaky hexagonal particles with a high aspect ratio played an important role in obtaining high permeability and high magnetic resonance frequency. The permeability , magnetic loss tangent tan δμ, and performance factor (PF) of the textured CoZn-18H hexagonal ferrite with the highest Snoek’s product (SP = 6.99 GHz) under 3.41 GHz were 1.66, 0.10, and 56.61 GHz, respectively. Compared with the traditional pure dielectric substrate, a planar inverted F antenna (PIFA) working at 3.0 GHz with a miniaturization rate of 18.1 % was simulated based on the textured CoZn-18H hexagonal ferrite. These results demonstrated that the method of preparing textured CoZn-18H hexagonal ferrites without the application of a magnetic field was effective and revealed the potential of textured planar hexagonal ferrites synthesized by the RTGG method of high-frequency and low-loss applications.
{"title":"Textured CoZn-18H hexaferrite with enhanced Snoek’s product and suppressed magnetic loss","authors":"Donglin He , Liangrui Tan , Peng Wang , Zhibiao Xu , Qinglin Li , Tao Wang","doi":"10.1016/j.jmmm.2024.172663","DOIUrl":"10.1016/j.jmmm.2024.172663","url":null,"abstract":"<div><div>Modern communications have created a great demand of magneto-dielectric functional materials having low loss and high permeability properties under the sub-6 GHz band. CoZn-18H planar hexagonal ferrites with strong magnetic anisotropy are more promising in meeting these requirements than that of traditional ferrites. The textured CoZn-18H hexagonal ferrites were synthesized by the reactive templated grain growth (RTGG) method to obtain high magnetic resonance frequency without sacrificing permeability. The layered texture composed of flaky hexagonal particles with a high aspect ratio played an important role in obtaining high permeability and high magnetic resonance frequency. The permeability <span><math><mrow><msup><mrow><mi>μ</mi></mrow><mo>′</mo></msup></mrow></math></span>, magnetic loss tangent tan δμ, and performance factor (<em>PF</em>) of the textured CoZn-18H hexagonal ferrite with the highest Snoek’s product (<em>SP</em> = 6.99 GHz) under 3.41 GHz were 1.66, 0.10, and 56.61 GHz, respectively. Compared with the traditional pure dielectric substrate, a planar inverted F antenna (PIFA) working at 3.0 GHz with a miniaturization rate of 18.1 % was simulated based on the textured CoZn-18H hexagonal ferrite. These results demonstrated that the method of preparing textured CoZn-18H hexagonal ferrites without the application of a magnetic field was effective and revealed the potential of textured planar hexagonal ferrites synthesized by the RTGG method of high-frequency and low-loss applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172663"},"PeriodicalIF":2.5,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-13DOI: 10.1016/j.jmmm.2024.172664
Guoliang Hu , Weizheng Lei , Xingsheng Xi , Tiannan Xu , Tongfei Tian
Magnetorheological (MR) dampers have a promising application in vehicle semi-active suspension system, but the direct application of MR dampers in vehicle semi-active suspension system inevitably requires a large amount of electrical energy from the on-board battery and there will be a power failure problem. At the same time, mechanical energy is converted into heat due to the friction between the cylinder and the damper piston of the MR damper. In order to avoid excessive energy waste and realize the self-powered supply of the MR damper to a certain extent, a new vibration energy harvesting MR damper (VEHMRD) is developed in this paper. First, energy harvesting, damping force and self-powered mathematical models are established. Then, the structural parameters of the proposed VEHMRD are designed, and the multi-objective water-cycle algorithm is applied to find out the optimal parameters of the proposed MR damper. Power generation and damping performance are simulated using Comsol software. Finally, a prototype is fabricated, and the power generation, damping force, and self-power ability of the VEHMRD are also tested. The experimental results are also compared with the simulated ones. The results show that the experimental induction voltage is lower than the simulated one with an error of about 15 %. The difference between the experimental damping force and the simulated damping force is small, with an error within 6 %, and the maximum damping force is about 1800 N at an applied current of 1.75A. When the collected electric energy is rectified and supplied to the MR damper, the damping force can reach over 400 N. The developed VEHMRD has a higher vibration energy harvesting capability. When powered by an external power source, the damping performance of the proposed MR damper is good. In addition, it can provide a certain damping force even when self-powered.
{"title":"Design and performance analysis of a vibration energy harvesting magnetorheological damper","authors":"Guoliang Hu , Weizheng Lei , Xingsheng Xi , Tiannan Xu , Tongfei Tian","doi":"10.1016/j.jmmm.2024.172664","DOIUrl":"10.1016/j.jmmm.2024.172664","url":null,"abstract":"<div><div>Magnetorheological (MR) dampers have a promising application in vehicle semi-active suspension system, but the direct application of MR dampers in vehicle semi-active suspension system inevitably requires a large amount of electrical energy from the on-board battery and there will be a power failure problem. At the same time, mechanical energy is converted into heat due to the friction between the cylinder and the damper piston of the MR damper. In order to avoid excessive energy waste and realize the self-powered supply of the MR damper to a certain extent, a new vibration energy harvesting MR damper (VEHMRD) is developed in this paper. First, energy harvesting, damping force and self-powered mathematical models are established. Then, the structural parameters of the proposed VEHMRD are designed, and the multi-objective water-cycle algorithm is applied to find out the optimal parameters of the proposed MR damper. Power generation and damping performance are simulated using Comsol software. Finally, a prototype is fabricated, and the power generation, damping force, and self-power ability of the VEHMRD are also tested. The experimental results are also compared with the simulated ones. The results show that the experimental induction voltage is lower than the simulated one with an error of about 15 %. The difference between the experimental damping force and the simulated damping force is small, with an error within 6 %, and the maximum damping force is about 1800 N at an applied current of 1.75A. When the collected electric energy is rectified and supplied to the MR damper, the damping force can reach over 400 N. The developed VEHMRD has a higher vibration energy harvesting capability. When powered by an external power source, the damping performance of the proposed MR damper is good. In addition, it can provide a certain damping force even when self-powered.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172664"},"PeriodicalIF":2.5,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bulk Fe2-xCrxCoSi (x = 0, 0.25, 0.5, 0.75, and 1) Heusler alloys have been prepared by arc melting method. Alloys with 0 ≤ x ≤ 0.75 show a highly ordered phase pure XA structure. However, 17 % of an impurity (A15 phase) was detected in the alloy with x = 1. The saturation magnetization (Ms) and Curie temperature (TC) decreased linearly with an increase in Cr content for alloys with x ≤ 0.75. Ms measured at 5 K followed the Slater–Pauling rule for half-metals. Ab initio calculations with the GGA + U approach revealed that spin polarization (P) increased with an increase in Cr and eventually reached 100 % for the alloys with x = 0.5. Though Fe-Co disorder affects P, it is still high (>98 %) for alloys with x ≥ 0.5. Despite the smaller bandgap (0.61 eV) of Fe1.5Cr0.5CoSi than FeCrCoSi (0.91 eV), it has higher Ms, elevated TC, and 100 % P. These factors, coupled with the challenges associated with obtaining phase pure FeCrCoSi alloy, make Fe1.5Cr0.5CoSi a preferred candidate for spintronic device applications.
通过电弧熔化法制备了块状 Fe2-xCrxCoSi（x = 0、0.25、0.5、0.75 和 1）Heusler 合金。0 ≤ x ≤ 0.75 的合金显示出高度有序的纯 XA 相结构。然而，在 x = 1 的合金中检测到了 17% 的杂质（A15 相）。对于 x ≤ 0.75 的合金，饱和磁化（Ms）和居里温度（TC）随着铬含量的增加而线性降低。5 K 时测得的 Ms 符合半金属的 Slater-Pauling 规则。采用 GGA + U 方法进行的 Ab initio 计算显示，自旋极化（P）随着铬含量的增加而增加，最终在 x = 0.5 的合金中达到 100%。虽然铁-钴无序会影响自旋极化，但 x ≥ 0.5 的合金的自旋极化仍然很高（98%）。尽管 Fe1.5Cr0.5CoSi 的带隙（0.61 eV）小于 FeCrCoSi（0.91 eV），但它具有更高的 Ms、更高的 TC 和 100% 的 P。
{"title":"Influence of atomic substitution on the structural stability and half-metallicity of Fe2-xCrxCoSi (x = 0 to 1) alloys","authors":"Subrata Biswas, Perumal Alagarsamy, Ananthakrishnan Srinivasan","doi":"10.1016/j.jmmm.2024.172648","DOIUrl":"10.1016/j.jmmm.2024.172648","url":null,"abstract":"<div><div>Bulk Fe<sub>2-</sub><em><sub>x</sub></em>Cr<em><sub>x</sub></em>CoSi (<em>x</em> = 0, 0.25, 0.5, 0.75, and 1) Heusler alloys have been prepared by arc melting method. Alloys with 0 ≤ <em>x</em> ≤ 0.75 show a highly ordered phase pure <em>XA</em> structure. However, 17 % of an impurity (<em>A</em>15 phase) was detected in the alloy with <em>x</em> = 1. The saturation magnetization (<em>M</em><sub>s</sub>) and Curie temperature (<em>T</em><sub>C</sub>) decreased linearly with an increase in Cr content for alloys with <em>x</em> ≤ 0.75. <em>M</em><sub>s</sub> measured at 5 K followed the Slater–Pauling rule for half-metals. <em>Ab initio</em> calculations with the GGA + U approach revealed that spin polarization (<em>P</em>) increased with an increase in Cr and eventually reached 100 % for the alloys with <em>x</em> = 0.5. Though Fe-Co disorder affects <em>P</em>, it is still high (>98 %) for alloys with <em>x</em> ≥ 0.5. Despite the smaller bandgap (0.61 eV) of Fe<sub>1.5</sub>Cr<sub>0.5</sub>CoSi than FeCrCoSi (0.91 eV), it has higher <em>M</em><sub>s</sub>, elevated <em>T</em><sub>C</sub>, and 100 % <em>P</em>. These factors, coupled with the challenges associated with obtaining phase pure FeCrCoSi alloy, make Fe<sub>1.5</sub>Cr<sub>0.5</sub>CoSi a preferred candidate for spintronic device applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172648"},"PeriodicalIF":2.5,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.jmmm.2024.172646
Frédéric Mazaleyrat
Soft magnetic composites (SMC) also known as powder cores are widely used in many applications because of their linearity, controllable permeability and isotropy. Because of the distributed air gap, the permeability is governed by the inner demagnetizing fields. To model the permeability dependence on the filling fraction, essentially two approaches are used both based on spatial periodicity hypothesis: the non magnetic grain boundary model and the effective medium theory. Actually, the first one works only for dense materials and the second works at low concentration. Both need fitting of two parameters, the inner demagnetizing factor and the particle susceptibility, just because the periodicity hypothesis is never verified for magnetic filling factors larger than 20%. A breakaway model is proposed based on the computation of mathematical esperance of the statistical distribution of magnetic chains and the subsequent determination of demagnetizing coefficient of an ellipsoid of equivalent aspect ratio. The model is collated with permeability data from the literature for spherical or non-spherical particles based SMCs and shows a excellent agreement with only one or even without fitting parameter in the whole concentration range.
{"title":"Statistical modeling of soft magnetic composites’ permeability","authors":"Frédéric Mazaleyrat","doi":"10.1016/j.jmmm.2024.172646","DOIUrl":"10.1016/j.jmmm.2024.172646","url":null,"abstract":"<div><div>Soft magnetic composites (SMC) also known as powder cores are widely used in many applications because of their linearity, controllable permeability and isotropy. Because of the distributed air gap, the permeability is governed by the inner demagnetizing fields. To model the permeability dependence on the filling fraction, essentially two approaches are used both based on spatial periodicity hypothesis: the non magnetic grain boundary model and the effective medium theory. Actually, the first one works only for dense materials and the second works at low concentration. Both need fitting of two parameters, the inner demagnetizing factor and the particle susceptibility, just because the periodicity hypothesis is never verified for magnetic filling factors larger than 20%. A breakaway model is proposed based on the computation of mathematical esperance of the statistical distribution of magnetic chains and the subsequent determination of demagnetizing coefficient of an ellipsoid of equivalent aspect ratio. The model is collated with permeability data from the literature for spherical or non-spherical particles based SMCs and shows a excellent agreement with only one or even without fitting parameter in the whole concentration range.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172646"},"PeriodicalIF":2.5,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-09DOI: 10.1016/j.jmmm.2024.172643
Anita Mongshi , Yves Armand Tene Deffo , Nicolas Mary , Pierre Tsafack , Jean-François Mogniotte , Benjamin Ducharne
In this work, an investigation is done to identify the magnetic non-destructive testing techniques and their related magnetization mechanisms and, eventually, the associated indicators that present the most distinguishable response to changes in steel properties due to the onset and evolution of starting corrosion by thermal oxidation at low temperatures. This is found by measuring magnetic responses of Magnetic Hysteresis Cycle (MHC), Magnetic Barkhausen Noise (MBN), and Magnetic Incremental Permeability (MIP) at the early stage of corrosion. Herein, the magnetization mechanism identified by the Domain Wall Bulging (DWB) effect and represented by the indicator Δ|Z|MIP from the MIP response is ranked the most sensitive indicator by Pearson’s linear correlation coefficient (LCC). It is immediately followed by the Domain Wall’s Irreversible Motions (DWIM) represented by the MBN coercivity indicator. Both mechanisms are associated with the structure and kinetic of the magnetic domains, respectively, under low and medium magnetic excitations. The low-temperature thermal oxidation process set out the constructive effect of the oxide layer in the strain relief effect on the overall magnetic response of the corroded specimen. Discussions and conclusions are provided, as well as perspectives regarding the applicability of magnetic non-destructive testing techniques.
{"title":"Magnetization mechanisms for non-destructive evaluation of low-carbon steels subject to early-stage low-temperature thermal oxidation","authors":"Anita Mongshi , Yves Armand Tene Deffo , Nicolas Mary , Pierre Tsafack , Jean-François Mogniotte , Benjamin Ducharne","doi":"10.1016/j.jmmm.2024.172643","DOIUrl":"10.1016/j.jmmm.2024.172643","url":null,"abstract":"<div><div>In this work, an investigation is done to identify the magnetic non-destructive testing techniques and their related magnetization mechanisms and, eventually, the associated indicators that present the most distinguishable response to changes in steel properties due to the onset and evolution of starting corrosion by thermal oxidation at low temperatures. This is found by measuring magnetic responses of Magnetic Hysteresis Cycle (MHC), Magnetic Barkhausen Noise (MBN), and Magnetic Incremental Permeability (MIP) at the early stage of corrosion. Herein, the magnetization mechanism identified by the Domain Wall Bulging (DWB) effect and represented by the indicator Δ|Z|<sub>MIP</sub> from the MIP response is ranked the most sensitive indicator by Pearson’s linear correlation coefficient (LCC). It is immediately followed by the Domain Wall’s Irreversible Motions (DWIM) represented by the MBN coercivity indicator. Both mechanisms are associated with the structure and kinetic of the magnetic domains, respectively, under low and medium magnetic excitations. The low-temperature thermal oxidation process set out the constructive effect of the oxide layer in the strain relief effect on the overall magnetic response of the corroded specimen. Discussions and conclusions are provided, as well as perspectives regarding the applicability of magnetic non-destructive testing techniques.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172643"},"PeriodicalIF":2.5,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper reports on the principle of signals demultiplexing in the structure ferromagnetic film/normal metal/magnonic crystal. It is discovered that in such a structure there is a formation of four band gaps — spin wave forbidden bands. It is shown that depending on the frequency, the signal comes out through different ports of the structure (ferromagnetic film or magnonic crystal), i.e. there is frequency division of channels. The influence of spin current on the signal coupling at frequencies inside the band gap significantly prevails over the effect of spin current at frequencies outside the band gap. The spin current allows effective control of the main line insertion loss of a directional coupler based on such a structure. The spin current has little effect on coupling factor and isolation.
{"title":"Control of spin wave demultiplexing using spin current","authors":"M.A. Morozova , N.D. Lobanov , O.V. Matveev , S.A. Nikitov","doi":"10.1016/j.jmmm.2024.172642","DOIUrl":"10.1016/j.jmmm.2024.172642","url":null,"abstract":"<div><div>The paper reports on the principle of signals demultiplexing in the structure ferromagnetic film/normal metal/magnonic crystal. It is discovered that in such a structure there is a formation of four band gaps — spin wave forbidden bands. It is shown that depending on the frequency, the signal comes out through different ports of the structure (ferromagnetic film or magnonic crystal), i.e. there is frequency division of channels. The influence of spin current on the signal coupling at frequencies inside the band gap significantly prevails over the effect of spin current at frequencies outside the band gap. The spin current allows effective control of the main line insertion loss of a directional coupler based on such a structure. The spin current has little effect on coupling factor and isolation.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172642"},"PeriodicalIF":2.5,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-08DOI: 10.1016/j.jmmm.2024.172633
X.-Y. Cui , Khanh Nam Vu , S.P. Ringer , Bernard Delley , C. Stampfl
Using ab initio calculations we investigate the adsorption of Co atoms, dimers and small cobalt clusters of 5 and 13 atoms on pristine graphene and graphene with a double vacancy. We report the atomic, electronic, magnetic and energetic properties of these systems. Stable adsorption configurations tend to maximise the number of cobalt-carbon bonds. On graphene, the adsorption energy of the clusters is only about 0.4 to 1 eV, and the clusters are relatively mobile on graphene. Interestingly, for different adsorbed Co13 isomers on graphene it is found that they converge to the same atomic structure. On graphene with a divacancy, the Co clusters bind in the divacancy site and isomerisation also occurs for the Co cluster system as well as for Co13. Co atoms and clusters can be effectively immobilised on the divacancy with corresponding adsorption energy being significantly enhanced by about 5 to 7 eV. All clusters act as electron donors in the interaction with the graphene/divacancy systems, and the amount of electron charge transfer increases with cluster size. Finite magnetic moments occur for all systems, where upon adsorption, the magnetic moment of the isolated Co atom (3) is significantly reduced due to electron transfer and bonding, resulting in values varying from 0.9-2.2 per Co atom. For the pristine graphene substrate, the total induced magnetic moments on the carbon atoms are negligible, while on the divacancy system, they are of the order of 0.1-0.3 . The attractive physical properties of these hybrid systems could find applications in catalysis and materials science.
我们利用 ab initio 计算研究了原始石墨烯和具有双空位的石墨烯上钴原子、二聚体以及 5 个和 13 个原子的小钴簇的吸附情况。我们报告了这些系统的原子、电子、磁性和能量特性。稳定的吸附构型倾向于使钴-碳键的数量最大化。在石墨烯上，团簇的吸附能仅约为 0.4 至 1 eV，而且团簇在石墨烯上具有相对的流动性。有趣的是，对于石墨烯上吸附的不同 Co13 异构体，我们发现它们趋同于相同的原子结构。在具有二价性的石墨烯上，Co 团簇结合在二价性位点上，Co5 团簇系统和 Co13 也会发生异构化。钴原子和簇可以有效地固定在二价位上，相应的吸附能显著提高了约 5 到 7 eV。所有团簇在与石墨烯/二价系统的相互作用中都充当电子供体，电子电荷转移量随团簇大小的增加而增加。所有体系的磁矩都是有限的，在吸附时，由于电子转移和键合，孤立的 Co 原子的磁矩（3μB）会显著降低，导致每个 Co 原子的磁矩值在≈0.9-2.2 μB 之间变化。对于原始石墨烯基底，碳原子上的总诱导磁矩可以忽略不计，而在二价体系上，它们的磁矩为 0.1-0.3 μB。这些杂化体系具有诱人的物理特性，可应用于催化和材料科学领域。
{"title":"Electronic and magnetic properties of cobalt clusters on pristine and divacancy graphene","authors":"X.-Y. Cui , Khanh Nam Vu , S.P. Ringer , Bernard Delley , C. Stampfl","doi":"10.1016/j.jmmm.2024.172633","DOIUrl":"10.1016/j.jmmm.2024.172633","url":null,"abstract":"<div><div>Using <em>ab initio</em> calculations we investigate the adsorption of Co atoms, dimers and small cobalt clusters of 5 and 13 atoms on pristine graphene and graphene with a double vacancy. We report the atomic, electronic, magnetic and energetic properties of these systems. Stable adsorption configurations tend to maximise the number of cobalt-carbon bonds. On graphene, the adsorption energy of the clusters is only about 0.4 to 1 eV, and the clusters are relatively mobile on graphene. Interestingly, for different adsorbed Co<sub>13</sub> isomers on graphene it is found that they converge to the same atomic structure. On graphene with a divacancy, the Co clusters bind in the divacancy site and isomerisation also occurs for the Co<span><math><msub><mrow></mrow><mrow><mn>5</mn></mrow></msub></math></span> cluster system as well as for Co<sub>13</sub>. Co atoms and clusters can be effectively immobilised on the divacancy with corresponding adsorption energy being significantly enhanced by about 5 to 7 eV. All clusters act as electron donors in the interaction with the graphene/divacancy systems, and the amount of electron charge transfer increases with cluster size. Finite magnetic moments occur for all systems, where upon adsorption, the magnetic moment of the isolated Co atom (3<span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span>) is significantly reduced due to electron transfer and bonding, resulting in values varying from <span><math><mo>≈</mo></math></span>0.9-2.2 <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span> per Co atom. For the pristine graphene substrate, the total induced magnetic moments on the carbon atoms are negligible, while on the divacancy system, they are of the order of 0.1-0.3 <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>B</mi></mrow></msub></math></span>. The attractive physical properties of these hybrid systems could find applications in catalysis and materials science.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172633"},"PeriodicalIF":2.5,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-08DOI: 10.1016/j.jmmm.2024.172644
Yu Hao , Janusz H. Hankiewicz , Robert E. Camley , Stephen E. Russek , Zbigniew Celinski
Standard magnetization measurements on samples of small magnetic particles may generate conflicting results. We compare the mass magnetization of MgZn ferrite particles in a compressed bulk material and in dry powder and find that at low fields the values can differ by as much as 50%. We show here that embedding the particles in a silicone matrix and measuring the NMR linewidth in combination with simulations establishes a new method to evaluate the magnetization of the particles at different fields and temperatures. The NMR results agree with the direct magnetization measurements of the powder samples and the magnetization measurements of the particles embedded in silicone. This work is motivated, in part, by studies on using small magnetic particles as MRI temperature indicators, and we compare the effectiveness of these particles for low-field and high-field MRI thermometry.
{"title":"Using NMR linewidth broadening for magnetic characterization of micrometer-size particles in silicone matrix","authors":"Yu Hao , Janusz H. Hankiewicz , Robert E. Camley , Stephen E. Russek , Zbigniew Celinski","doi":"10.1016/j.jmmm.2024.172644","DOIUrl":"10.1016/j.jmmm.2024.172644","url":null,"abstract":"<div><div>Standard magnetization measurements on samples of small magnetic particles may generate conflicting results. We compare the mass magnetization of MgZn ferrite particles in a compressed bulk material and in dry powder and find that at low fields the values can differ by as much as 50%. We show here that embedding the particles in a silicone matrix and measuring the NMR linewidth in combination with simulations establishes a new method to evaluate the magnetization of the particles at different fields and temperatures. The NMR results agree with the direct magnetization measurements of the powder samples and the magnetization measurements of the particles embedded in silicone. This work is motivated, in part, by studies on using small magnetic particles as MRI temperature indicators, and we compare the effectiveness of these particles for low-field and high-field MRI thermometry.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"612 ","pages":"Article 172644"},"PeriodicalIF":2.5,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142660800","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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