Pub Date : 2025-12-06DOI: 10.1016/j.jmmm.2025.173746
Yameng Liu , Jing Guo , Zhilei Wang , Yanguo Li , Fan Zhao , Zhihao Zhang , Xinhua Liu
The core vibration of motors is associated with the magnetostriction of the non-oriented silicon steel. The inherent structure is regarded as the intrinsic factor for magnetostriction. In this work, a magnetostriction prediction model based on feature screening was proposed to effectively identify key feature combinations affecting magnetostriction, including correlation screening, feature weight ranking, and recursive feature selection. The results indicated that the key features responsible for magnetostriction were absolute electronegativity, third ionization energy, and electron affinity. The support vector regression algorithm was used to build the “key features combination-magnetostriction” model with the R2 reaching 0.98. Elements doping, such as Al, Ti, V, etc., result in an enhancement of the magnetostriction of the non-oriented silicon steel except Mn and co. this established machine learning model demonstrated excellent reliability in the prediction of magnetostriction of commercial and multi-component high-performance non-oriented silicon steel, based on which, symbolic regression algorithm was applied to construct the mathematical expression of magnetostriction. The feature selection framework proposed in this work provides valuable ideas for predicting the magnetostriction of silicon steel materials
{"title":"Magnetostriction model for non-oriented silicon steel based on physicochemical parameters of alloying elements","authors":"Yameng Liu , Jing Guo , Zhilei Wang , Yanguo Li , Fan Zhao , Zhihao Zhang , Xinhua Liu","doi":"10.1016/j.jmmm.2025.173746","DOIUrl":"10.1016/j.jmmm.2025.173746","url":null,"abstract":"<div><div>The core vibration of motors is associated with the magnetostriction of the non-oriented silicon steel. The inherent structure is regarded as the intrinsic factor for magnetostriction. In this work, a magnetostriction prediction model based on feature screening was proposed to effectively identify key feature combinations affecting magnetostriction, including correlation screening, feature weight ranking, and recursive feature selection. The results indicated that the key features responsible for magnetostriction were absolute electronegativity, third ionization energy, and electron affinity. The support vector regression algorithm was used to build the “key features combination-magnetostriction” model with the <em>R</em><sup>2</sup> reaching 0.98. Elements doping, such as Al, Ti, V, etc., result in an enhancement of the magnetostriction of the non-oriented silicon steel except Mn and co. this established machine learning model demonstrated excellent reliability in the prediction of magnetostriction of commercial and multi-component high-performance non-oriented silicon steel, based on which, symbolic regression algorithm was applied to construct the mathematical expression of magnetostriction. The feature selection framework proposed in this work provides valuable ideas for predicting the magnetostriction of silicon steel materials</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173746"},"PeriodicalIF":3.0,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733825","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 : 2025-12-05DOI: 10.1016/j.jmmm.2025.173738
S.A. de Oliveira , R.T. Doumbi , A. de Morais , J.M.D. Neto , E.C. Souza , F. Bohn , A. Ferreira , F. Vaz , C. Lopes , J.C. Denardin , G.V. Kurlyandskaya , M.A. Correa
CoFe-based rapidly quenched amorphous ribbons are good model materials for studying the Anomalous Nernst Effect. They offer a promising platform to explore the efficiency of the converstion of thermal energy into electric energy, particularly compared to other sample geometries. However, the contribution of magnetic anisotropy to thermomagnetic properties plays a critical role in increasing the energy conversion efficiency for future technological applications. In this study, a flexible amorphous ribbon with the Co67Fe4Mo1.5Si16.5B11 composition, showing a strong in-plane shape magnetic anisotropy, was investigated through the Anomalous Nernst Effect (ANE) by varying both the intensity and angle of the external magnetic field, as well as the thermal gradient intensity. The microstructure and morphological features were analyzed, and the electrical properties were evaluated to elucidate their individual contributions to the thermomagnetic signal. A straightforward theoretical model was also proposed to predict magnetic and thermomagnetic responses in systems dominated by in-plane shape magnetic anisotropies. The CoFe-based amorphous ribbon experimentally reached an effective ANE coefficient (Seff) value of around . For the Anomalous Nerst coefficient (, which considers the reduced temperature on the Co-base ribbon, the value is around 0. These results position Co67Fe4Mo1.5Si16.5B11 amorphous ribbons as highly promising for thermal energy conversion and highly sensitive magnetic field detectors, among other applications.
{"title":"Experimental and theoretical approaches for thermomagnetic properties of CoFe-based flexible amorphous ribbons: shape anisotropy contribution","authors":"S.A. de Oliveira , R.T. Doumbi , A. de Morais , J.M.D. Neto , E.C. Souza , F. Bohn , A. Ferreira , F. Vaz , C. Lopes , J.C. Denardin , G.V. Kurlyandskaya , M.A. Correa","doi":"10.1016/j.jmmm.2025.173738","DOIUrl":"10.1016/j.jmmm.2025.173738","url":null,"abstract":"<div><div>CoFe-based rapidly quenched amorphous ribbons are good model materials for studying the Anomalous Nernst Effect. They offer a promising platform to explore the efficiency of the converstion of thermal energy into electric energy, particularly compared to other sample geometries. However, the contribution of magnetic anisotropy to thermomagnetic properties plays a critical role in increasing the energy conversion efficiency for future technological applications. In this study, a flexible amorphous ribbon with the Co<sub>67</sub>Fe<sub>4</sub>Mo<sub>1.5</sub>Si<sub>16.5</sub>B<sub>11</sub> composition, showing a strong in-plane shape magnetic anisotropy, was investigated through the Anomalous Nernst Effect (ANE) by varying both the intensity and angle of the external magnetic field, as well as the thermal gradient intensity. The microstructure and morphological features were analyzed, and the electrical properties were evaluated to elucidate their individual contributions to the thermomagnetic signal. A straightforward theoretical model was also proposed to predict magnetic and thermomagnetic responses in systems dominated by in-plane shape magnetic anisotropies. The CoFe-based amorphous ribbon experimentally reached an effective ANE coefficient (S<sub>eff</sub>) value of around <span><math><mn>1.23</mn><mspace></mspace><mi>μV</mi><mo>/</mo><mi>K</mi></math></span>. For the Anomalous Nerst coefficient (<span><math><msub><mi>S</mi><mi>ANE</mi></msub><mo>)</mo></math></span>, which considers the reduced temperature on the Co-base ribbon, the value is around 0<span><math><mn>.17</mn><mspace></mspace><mi>μV</mi><mo>/</mo><mi>K</mi></math></span>. These results position Co<sub>67</sub>Fe<sub>4</sub>Mo<sub>1.5</sub>Si<sub>16.5</sub>B<sub>11</sub> amorphous ribbons as highly promising for thermal energy conversion and highly sensitive magnetic field detectors, among other applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173738"},"PeriodicalIF":3.0,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733801","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 : 2025-12-05DOI: 10.1016/j.jmmm.2025.173740
F. Rezaee, H. Shokrollahi, M.R. Tayebi, N. Askarzadeh
The intricate interplay between dopant concentration and sintering additives governs the structural and magnetic behavior of Mn-Zn ferrites, offering pathways to tailor their properties for advanced applications. This study presents an investigation into the structural, microstructural, and magnetic properties of Y3+-substituted Mn-Zn-Li ferrites synthesized via solid-state route at relatively low sintering temperature (1100 °C) in air, incorporating multi-component sintering additives (SiO2, CaO, TiO2, and Bi2O3). Samples with nominal compositions YxLi0.14Mn0.4Zn0.32Fe2.14-xO4 (x = 0–0.2) were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), density measurements, and vibrating sample magnetometry (VSM). XRD data confirmed nearly pure spinel phases across all doping levels, with gradual lattice expansion due to Y3+ incorporation. The x = 0.025 composition yielded the highest magnetization (∼60 emu/g) and lowest amount of coercivity (∼19 Oe), highlighting its potential for applications requiring stable magnetic response and grain size control. These findings demonstrate that synergistic Y3+ doping and additive-assisted sintering can effectively modulate ferrite microstructure and magnetic softness, with x = 0.2 emerging as an optimized composition for next-generation soft magnetic ceramics.
{"title":"Air sintering of Y-doped Mn-Zn-Li ferrites at reduced temperatures: additive-assisted enhancement of magnetic properties","authors":"F. Rezaee, H. Shokrollahi, M.R. Tayebi, N. Askarzadeh","doi":"10.1016/j.jmmm.2025.173740","DOIUrl":"10.1016/j.jmmm.2025.173740","url":null,"abstract":"<div><div>The intricate interplay between dopant concentration and sintering additives governs the structural and magnetic behavior of Mn-Zn ferrites, offering pathways to tailor their properties for advanced applications. This study presents an investigation into the structural, microstructural, and magnetic properties of Y<sup>3+</sup>-substituted Mn-Zn-Li ferrites synthesized via solid-state route at relatively low sintering temperature (1100 °C) in air, incorporating multi-component sintering additives (SiO<sub>2</sub>, CaO, TiO<sub>2</sub>, and Bi<sub>2</sub>O<sub>3</sub>). Samples with nominal compositions Y<sub>x</sub>Li<sub>0.14</sub>Mn<sub>0.4</sub>Zn<sub>0.32</sub>Fe<sub>2.14-x</sub>O<sub>4</sub> (x = 0–0.2) were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), density measurements, and vibrating sample magnetometry (VSM). XRD data confirmed nearly pure spinel phases across all doping levels, with gradual lattice expansion due to Y<sup>3+</sup> incorporation<em>.</em> The x = 0.025 composition yielded the highest magnetization (∼60 emu/g) and lowest amount of coercivity (∼19 Oe), highlighting its potential for applications requiring stable magnetic response and grain size control. These findings demonstrate that synergistic Y<sup>3+</sup> doping and additive-assisted sintering can effectively modulate ferrite microstructure and magnetic softness, with x = 0.2 emerging as an optimized composition for next-generation soft magnetic ceramics.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173740"},"PeriodicalIF":3.0,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733798","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 : 2025-12-05DOI: 10.1016/j.jmmm.2025.173743
Jiahao Dong , Jiayuan Li , Bowen Jin , Zhenkun Li , Deyi Wang
Thixotropy represents a distinctive phenomenon within the field of fluid rheology. The thixotropic behavior of magnetic fluids is typically weak and frequently neglected in conventional rheological investigations. In this study, a rheometer was employed in conjunction with both the thixotropic loop method and the three-stage thixotropic method to systematically examine the thixotropic characteristics of four distinct magnetic fluids containing varying volume fractions of bentonite (0 %, 8 %, 10 %, and 12 %). Particular emphasis was placed on analyzing the effects of magnetic field strength and bentonite content on the thixotropic properties of these fluids. The results demonstrate that magnetic field strength exerts a significant influence on the thixotropy of magnetic fluids, attributable to the formation of elongated and more aggregated chain-like structures of magnetic particles under the applied field, thereby enhancing the time-dependent breakdown and recovery of the internal structure. Furthermore, the incorporation of bentonite markedly improves the thixotropic performance. Under identical magnetic field conditions, the area of the thixotropic loop for bentonite-containing magnetic fluids is substantially greater than that of their bentonite-free counterparts, with thixotropy increasing progressively with rising bentonite content. Specifically, the thixotropy of MF4 (containing 12 % bentonite) is approximately three times higher than that of MF1. This enhancement arises from the synergistic interaction between the three-dimensional network formed by bentonite particles and the chain-like assemblies of magnetic particles, resulting in a composite structural framework that enhances both structural stability and recovery capacity. In summary, magnetic field strength and bentonite content are critical factors in modulating the thixotropic behavior of magnetic fluids. The synergistic structural effects induced by these two parameters offer a viable approach for tailoring the thixotropic properties of such fluids, thereby establishing a foundation for their practical engineering applications.
{"title":"Effect of bentonite on thixotropy of magnetic fluid","authors":"Jiahao Dong , Jiayuan Li , Bowen Jin , Zhenkun Li , Deyi Wang","doi":"10.1016/j.jmmm.2025.173743","DOIUrl":"10.1016/j.jmmm.2025.173743","url":null,"abstract":"<div><div>Thixotropy represents a distinctive phenomenon within the field of fluid rheology. The thixotropic behavior of magnetic fluids is typically weak and frequently neglected in conventional rheological investigations. In this study, a rheometer was employed in conjunction with both the thixotropic loop method and the three-stage thixotropic method to systematically examine the thixotropic characteristics of four distinct magnetic fluids containing varying volume fractions of bentonite (0 %, 8 %, 10 %, and 12 %). Particular emphasis was placed on analyzing the effects of magnetic field strength and bentonite content on the thixotropic properties of these fluids. The results demonstrate that magnetic field strength exerts a significant influence on the thixotropy of magnetic fluids, attributable to the formation of elongated and more aggregated chain-like structures of magnetic particles under the applied field, thereby enhancing the time-dependent breakdown and recovery of the internal structure. Furthermore, the incorporation of bentonite markedly improves the thixotropic performance. Under identical magnetic field conditions, the area of the thixotropic loop for bentonite-containing magnetic fluids is substantially greater than that of their bentonite-free counterparts, with thixotropy increasing progressively with rising bentonite content. Specifically, the thixotropy of MF4 (containing 12 % bentonite) is approximately three times higher than that of MF1. This enhancement arises from the synergistic interaction between the three-dimensional network formed by bentonite particles and the chain-like assemblies of magnetic particles, resulting in a composite structural framework that enhances both structural stability and recovery capacity. In summary, magnetic field strength and bentonite content are critical factors in modulating the thixotropic behavior of magnetic fluids. The synergistic structural effects induced by these two parameters offer a viable approach for tailoring the thixotropic properties of such fluids, thereby establishing a foundation for their practical engineering applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173743"},"PeriodicalIF":3.0,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733791","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 : 2025-12-05DOI: 10.1016/j.jmmm.2025.173741
Ning Wang , Pengning Zhang , Lihua Mou , Jian Zhang , Hong Cheng , Cong Wang
The elevated temperature rise that occurs during the operation of nanocrystalline high-frequency transformers can significantly impact their performance. However, the extent to which temperature affects the performance of such transformers has not yet been quantitatively assessed in previous research. In this research, a three-dimensional electromagnetic-thermal finite element simulation model is developed for a 10 kHz, 20 kW nanocrystalline high-frequency transformer, with temperature incorporated as a key parameter influencing both the magnetic properties of the core and the electrical conductivity of the windings. Finite element simulations are conducted under no-load and short-circuit conditions, considering both unidirectional magnetic-thermal coupling (neglecting temperature feedback) and bidirectional magnetic-thermal coupling (accounting for temperature feedback). An experimental test platform is established to perform corresponding no-load and short-circuit tests on the transformer prototype. The comparison between simulation and experimental results demonstrates that bidirectional coupling simulations can accurately capture the dynamic influence of temperature variations on transformer performance, thereby enhancing the reliability of the simulation. Under no-load conditions, the bidirectional magnetic-thermal coupling simulation predicts a reduction in core temperature by 0.44 °C compared to the unidirectional simulation, with only a 0.01 °C deviation from the measured value, indicating excellent thermal stability of the nanocrystalline core. Under short-circuit conditions, the bidirectional simulation predicts an increase in winding temperature by 5.38 °C compared to the unidirectional simulation, which is 1.67 °C lower than the measured value, suggesting that the copper winding performance is more sensitive to temperature. This research provides a reliable theoretical basis for simulation calculations, structural optimization, and thermal management of nanocrystalline transformers.
{"title":"Research on electric-magnetic-thermal multiphysics coupling of nanocrystalline high-frequency transformers","authors":"Ning Wang , Pengning Zhang , Lihua Mou , Jian Zhang , Hong Cheng , Cong Wang","doi":"10.1016/j.jmmm.2025.173741","DOIUrl":"10.1016/j.jmmm.2025.173741","url":null,"abstract":"<div><div>The elevated temperature rise that occurs during the operation of nanocrystalline high-frequency transformers can significantly impact their performance. However, the extent to which temperature affects the performance of such transformers has not yet been quantitatively assessed in previous research. In this research, a three-dimensional electromagnetic-thermal finite element simulation model is developed for a 10 kHz, 20 kW nanocrystalline high-frequency transformer, with temperature incorporated as a key parameter influencing both the magnetic properties of the core and the electrical conductivity of the windings. Finite element simulations are conducted under no-load and short-circuit conditions, considering both unidirectional magnetic-thermal coupling (neglecting temperature feedback) and bidirectional magnetic-thermal coupling (accounting for temperature feedback). An experimental test platform is established to perform corresponding no-load and short-circuit tests on the transformer prototype. The comparison between simulation and experimental results demonstrates that bidirectional coupling simulations can accurately capture the dynamic influence of temperature variations on transformer performance, thereby enhancing the reliability of the simulation. Under no-load conditions, the bidirectional magnetic-thermal coupling simulation predicts a reduction in core temperature by 0.44 °C compared to the unidirectional simulation, with only a 0.01 °C deviation from the measured value, indicating excellent thermal stability of the nanocrystalline core. Under short-circuit conditions, the bidirectional simulation predicts an increase in winding temperature by 5.38 °C compared to the unidirectional simulation, which is 1.67 °C lower than the measured value, suggesting that the copper winding performance is more sensitive to temperature. This research provides a reliable theoretical basis for simulation calculations, structural optimization, and thermal management of nanocrystalline transformers.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173741"},"PeriodicalIF":3.0,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733795","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 : 2025-12-04DOI: 10.1016/j.jmmm.2025.173742
Himanshu, J.J. Pulikkotil
We present a theoretical investigation into the pressure-driven magnetic phase transitions of the itinerant ferromagnet, LaCrGe3. The study employs the Korringa–Kohn–Rostoker (KKR) method, combined with the Coherent Potential Approximation (CPA), to calculate the local magnetic moments of Cr in various magnetic configurations: ferromagnetic (FM), antiferromagnetic (AFM), and, crucially, the disordered local moment (DLM) state. A key finding is that referencing the stability of the FM and AFM phases against the DLM state, rather than the conventional nonmagnetic (NM) state, dramatically improves agreement with experimental observations. This approach yielded a FM-DLM degeneracy at approximately , a significantly more accurate prediction for the critical pressure compared to the roughly obtained using the NM reference (experimental critical pressure is 2.2 GPa). Furthermore, the calculated energy difference between the FM and DLM states at ambient pressure accurately reproduces the experimental Curie temperature () of 88 K, consistent with the observed decrease in under pressure. The persistence of local moments in the DLM state above offers a more physically realistic description of the paramagnetic state. Our results underscore the profound importance of considering the DLM state for precise predictions of pressure-induced magnetic transitions and for a comprehensive understanding of quantum criticality in itinerant ferromagnets.
{"title":"Predicting magnetic transitions under pressure in LaCrGe3: Role of disordered local moment state","authors":"Himanshu, J.J. Pulikkotil","doi":"10.1016/j.jmmm.2025.173742","DOIUrl":"10.1016/j.jmmm.2025.173742","url":null,"abstract":"<div><div>We present a theoretical investigation into the pressure-driven magnetic phase transitions of the itinerant ferromagnet, LaCrGe<sub>3</sub>. The study employs the Korringa–Kohn–Rostoker (KKR) method, combined with the Coherent Potential Approximation (CPA), to calculate the local magnetic moments of Cr in various magnetic configurations: ferromagnetic (FM), antiferromagnetic (AFM), and, crucially, the disordered local moment (DLM) state. A key finding is that referencing the stability of the FM and AFM phases against the DLM state, rather than the conventional nonmagnetic (NM) state, dramatically improves agreement with experimental observations. This approach yielded a FM-DLM degeneracy at approximately <span><math><mrow><mn>5</mn><mspace></mspace><mi>GPa</mi></mrow></math></span>, a significantly more accurate prediction for the critical pressure compared to the roughly <span><math><mrow><mn>10</mn><mspace></mspace><mi>GPa</mi></mrow></math></span> obtained using the NM reference (experimental critical pressure is 2.2 GPa). Furthermore, the calculated energy difference between the FM and DLM states at ambient pressure accurately reproduces the experimental Curie temperature (<span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>C</mi></mrow></msub></math></span>) of 88 K, consistent with the observed decrease in <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>C</mi></mrow></msub></math></span> under pressure. The persistence of local moments in the DLM state above <span><math><msub><mrow><mi>T</mi></mrow><mrow><mi>C</mi></mrow></msub></math></span> offers a more physically realistic description of the paramagnetic state. Our results underscore the profound importance of considering the DLM state for precise predictions of pressure-induced magnetic transitions and for a comprehensive understanding of quantum criticality in itinerant ferromagnets.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173742"},"PeriodicalIF":3.0,"publicationDate":"2025-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733800","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 : 2025-12-03DOI: 10.1016/j.jmmm.2025.173739
F. Azim , J. Mohapatra , A. Sharmin , P. Joshi , J.P. Liu , S.R. Mishra
This study reports the magnetic and magnetocaloric properties of transition-metal-doped Cr-Mn3O4 and Co-Mn3O4 synthesized via a facile autocombustion method. The X-ray diffraction (XRD) results confirmed the tetragonal structure of Mn3O4, Co-Mn3O4, and the cubic structure of Cr-Mn3O4. X-ray photoelectron spectroscopy (XPS) confirmed the oxidation states of individual transition-metal ions. The Curie temperatures, Tc, measured from Magnetization vs. Temperature curves, are 53 and 182 K for Cr-Mn3O4 and Co-Mn3O4, respectively. High coercivity, Mn3O4, (Hc ∼ 10 kOe) turned soft with reduced Hc ∼ 9.2 and 2.8 kOe upon Co2+ and Cr3+ doping. The second-order phase transition nature of doped compounds was confirmed from the Arrot plots. Electron spin resonance (ESR) confirmed the paramagnetic nature of these compounds at room temperature. The maximum change in magnetic entropy, │ΔSMax│, and corresponding relative cooling power, RCP, are recorded as 2.41, 7.63, 4.51 Jkg−1 K−1 and 40, 256, 74 Jkg−1 for Mn3O4, Cr-Mn3O4, and Co-Mn3O4 compounds, respectively. Nearly 200 % and 87 %, a record increase in │ΔSMax│ value, is displayed upon Cr and Co doping in Mn3O4 compared to the pure Mn3O4 compound. The improved MCE performance of these doped Mn3O4 compounds makes them promising candidates for magnetic refrigeration applications.
{"title":"Enhanced Magnetocaloric properties of transition metal-doped Mn3O4 compounds","authors":"F. Azim , J. Mohapatra , A. Sharmin , P. Joshi , J.P. Liu , S.R. Mishra","doi":"10.1016/j.jmmm.2025.173739","DOIUrl":"10.1016/j.jmmm.2025.173739","url":null,"abstract":"<div><div>This study reports the magnetic and magnetocaloric properties of transition-metal-doped Cr-Mn<sub>3</sub>O<sub>4</sub> and Co-Mn<sub>3</sub>O<sub>4</sub> synthesized <em>via</em> a facile autocombustion method. The X-ray diffraction (XRD) results confirmed the tetragonal structure of Mn<sub>3</sub>O<sub>4</sub>, Co-Mn<sub>3</sub>O<sub>4</sub>, and the cubic structure of Cr-Mn<sub>3</sub>O<sub>4.</sub> X-ray photoelectron spectroscopy (XPS) confirmed the oxidation states of individual transition-metal ions. The Curie temperatures, <em>T</em><sub><em>c</em></sub>, measured from Magnetization <em>vs.</em> Temperature curves, are 53 and 182 K for Cr-Mn<sub>3</sub>O<sub>4</sub> and Co-Mn<sub>3</sub>O<sub>4</sub>, respectively. High coercivity, Mn<sub>3</sub>O<sub>4,</sub> (<em>H</em><sub><em>c</em></sub> ∼ 10 kOe) turned soft with reduced <em>H</em><sub><em>c</em></sub> ∼ 9.2 and 2.8 kOe upon Co<sup>2+</sup> and Cr<sup>3+</sup> doping. The second-order phase transition nature of doped compounds was confirmed from the Arrot plots. Electron spin resonance (ESR) confirmed the paramagnetic nature of these compounds at room temperature. The maximum change in magnetic entropy, │<em>ΔS</em><sub><em>Max</em></sub>│, and corresponding relative cooling power, <em>RCP,</em> are recorded as 2.41, 7.63, 4.51 Jkg<sup>−1</sup> K<sup>−1</sup> and 40, 256, 74 Jkg<sup>−1</sup> for Mn<sub>3</sub>O<sub>4,</sub> Cr-Mn<sub>3</sub>O<sub>4</sub>, and Co-Mn<sub>3</sub>O<sub>4</sub> compounds, respectively. Nearly 200 % and 87 %, a record increase in │<em>ΔS</em><sub><em>Max</em></sub>│ value, is displayed upon Cr and Co doping in Mn<sub>3</sub>O<sub>4</sub> compared to the pure Mn<sub>3</sub>O<sub>4</sub> compound. The improved MCE performance of these doped Mn<sub>3</sub>O<sub>4</sub> compounds makes them promising candidates for magnetic refrigeration applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173739"},"PeriodicalIF":3.0,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145682716","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}
This study investigates the structural evolution, magnetic behavior, and thermoelectric properties of MnMgAlFeCu high-entropy alloy (HEA) processed through mechanical alloying, annealing, and spark plasma sintering (SPS). X-ray diffraction analysis revealed that the as-milled powder exhibited a BCC phase alongside a -brass-type phase, which transformed into MgCu2 and AlFe-type phases upon annealing along with an increase in crystallite size. SPS at 900oC significantly reduced the MgCu2 phase and increased the -brass-type phase, influencing both magnetic and electrical properties. Magnetometric and electron paramagnetic resonance(EPR) analysis revealed significant changes as a result of annealing. It is observed that annealing heals the defects and relaxes strain resulting into nearly isotropic EPR spectrum. The saturation magnetization increased from 20.3 emu/g (as-milled) to 44.4 emu/g (SPSed), while coercivity decreased from 556.6 Oe to 33.3 Oe at 2K, indicating enhanced soft magnetic behavior. Temperature-dependent magnetization studies showed an increase in blocking temperature and Curie temperature, demonstrating improved magnetic stability with annealing and SPS. Decrease in Seebeck coefficient and increase in electrical conductivity upon annealing is attributed to the formation of MgCu2 Laves phase, improved grain structure and reduced energy filtering at grain boundaries. SPS led to slight reduction in conductivity due to phase heterogeneity, but the overall power factor increased, highlighting the material’s potential for thermoelectric applications. These findings demonstrate that controlled heat treatments can tailor the structural, magnetic, and thermoelectric properties of MnMgAlFeCu HEA. The enhanced soft magnetic behavior and thermoelectric performance make it a promising candidate for energy-efficient magnetic and electronic applications.
{"title":"Structural evolution, magnetic and thermoelectric properties of low density MnMgAlFeCu HEA on heat treatment and spark plasma sintering","authors":"Pema Chida Sherpa , Yagnesh Shadangi , Shradha Bhatt , Nilay Krishna Mukhopadhyay , Ajay Tripathi , Archana Tiwari","doi":"10.1016/j.jmmm.2025.173737","DOIUrl":"10.1016/j.jmmm.2025.173737","url":null,"abstract":"<div><div>This study investigates the structural evolution, magnetic behavior, and thermoelectric properties of MnMgAlFeCu high-entropy alloy (HEA) processed through mechanical alloying, annealing, and spark plasma sintering (SPS). X-ray diffraction analysis revealed that the as-milled powder exhibited a BCC phase alongside a <span><math><mi>γ</mi></math></span>-brass-type phase, which transformed into MgCu<sub>2</sub> and AlFe-type phases upon annealing along with an increase in crystallite size. SPS at 900<sup>o</sup>C significantly reduced the MgCu<sub>2</sub> phase and increased the <span><math><mi>γ</mi></math></span>-brass-type phase, influencing both magnetic and electrical properties. Magnetometric and electron paramagnetic resonance(EPR) analysis revealed significant changes as a result of annealing. It is observed that annealing heals the defects and relaxes strain resulting into nearly isotropic EPR spectrum. The saturation magnetization increased from 20.3 emu/g (as-milled) to 44.4 emu/g (SPSed), while coercivity decreased from 556.6 Oe to 33.3 Oe at 2K, indicating enhanced soft magnetic behavior. Temperature-dependent magnetization studies showed an increase in blocking temperature and Curie temperature, demonstrating improved magnetic stability with annealing and SPS. Decrease in Seebeck coefficient and increase in electrical conductivity upon annealing is attributed to the formation of MgCu<sub>2</sub> Laves phase, improved grain structure and reduced energy filtering at grain boundaries. SPS led to slight reduction in conductivity due to phase heterogeneity, but the overall power factor increased, highlighting the material’s potential for thermoelectric applications. These findings demonstrate that controlled heat treatments can tailor the structural, magnetic, and thermoelectric properties of MnMgAlFeCu HEA. The enhanced soft magnetic behavior and thermoelectric performance make it a promising candidate for energy-efficient magnetic and electronic applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173737"},"PeriodicalIF":3.0,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733793","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 : 2025-12-03DOI: 10.1016/j.jmmm.2025.173735
Shahzab Raza , Mehran Khan Alam , Guangbing Han , Zhaoguo Qiu , Shishou Kang
The effect of Hf addition on the crystal structure, microstructure, and magnetic properties of Sm(Co0.97-xFe0.03Hfx)7.2 (x = 0, 0.1, 0.2, 0.3) nanoflakes prepared by surfactant-assisted ball milling at different milling times has been investigated. X-ray diffraction (XRD) analysis reveals that the as-prepared nanoflakes possess a 2:17-type hexagonal crystal structure, with no impurity phases detected upon Hf doping. Hf doping at x = 0.1 enhanced the magnetic anisotropy and exchange coupling interactions, leading to an increase in coercivity. A high coercivity of 5.4 kOe and a maximum energy product (BH)ₘₐₓ of 73 kJ/m3 were achieved. Further Hf doping (x = 0.2 and 0.3) deteriorates performance due to microstructural distortion and reduced exchange coupling. However, initial magnetization curves reveal that the coercivity mechanism of the as-prepared nanoflakes varies with Hf content. For x = 0, domain wall pinning is the dominant coercivity mechanism, whereas for x = 0.1, magnetic domain nucleation becomes the dominant mechanism. Henkel plots reveal strong exchange coupling interactions for x = 0.1, and dominant magnetostatic interactions at x = 0.2 and x = 0.3 in nanoflakes after 1 h of ball milling.
{"title":"Advanced magnetic properties of Sm2Co17-based nanoflakes with Hf-doping prepared by surfactant-assisted ball milling","authors":"Shahzab Raza , Mehran Khan Alam , Guangbing Han , Zhaoguo Qiu , Shishou Kang","doi":"10.1016/j.jmmm.2025.173735","DOIUrl":"10.1016/j.jmmm.2025.173735","url":null,"abstract":"<div><div>The effect of Hf addition on the crystal structure, microstructure, and magnetic properties of Sm(Co<sub>0.97-x</sub>Fe<sub>0.03</sub>Hf<sub>x</sub>)<sub>7.2</sub> (x = 0, 0.1, 0.2, 0.3) nanoflakes prepared by surfactant-assisted ball milling at different milling times has been investigated. X-ray diffraction (XRD) analysis reveals that the as-prepared nanoflakes possess a 2:17-type hexagonal crystal structure, with no impurity phases detected upon Hf doping. Hf doping at x = 0.1 enhanced the magnetic anisotropy and exchange coupling interactions, leading to an increase in coercivity. A high coercivity of 5.4 kOe and a maximum energy product (BH)ₘₐₓ of 73 kJ/m<sup>3</sup> were achieved. Further Hf doping (x = 0.2 and 0.3) deteriorates performance due to microstructural distortion and reduced exchange coupling. However, initial magnetization curves reveal that the coercivity mechanism of the as-prepared nanoflakes varies with Hf content. For x = 0, domain wall pinning is the dominant coercivity mechanism, whereas for x = 0.1, magnetic domain nucleation becomes the dominant mechanism. Henkel plots reveal strong exchange coupling interactions for x = 0.1, and dominant magnetostatic interactions at x = 0.2 and x = 0.3 in nanoflakes after 1 h of ball milling.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173735"},"PeriodicalIF":3.0,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733796","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}
In this study, RFeO3 nanoparticles were synthesized by sol-gel method to investigate the magnetic and photocatalytic properties of these perovskites. The morphology of the samples were investigated by field emission scanning electron microscopy. Beside x-ray diffraction patterns showed the orthorhombic structure with Pbnm space group with no impurity. For magnetic study of the RFeO3 nanoparticles (NPs) the field-cooled and zero-field-cooled measurements were used. For this magnetic measurement, a quantum design PPMS system is used. In this way, the spin reorientation temperature (TSR) and Neel temperature (TN) of the samples were extracted, too. Next, diffuse reflectance spectroscopy analysis was used to calculate the band gap energy (Eg) of the samples according to the Kubelka-Munk function. The calculated values determined that the Eg values became more by decreasing the ionic radius of the rare earth elements in RFeO3 NPs. At last, the photocatalytic activity of the RFeO3 NPs was studied by calculating the degradation of methylene Blue (MB) dye solution. Therefore, the results showed that LaFeO3 NPs has the highest degradation percent ∼96 % in 120 min.
{"title":"The FC & ZFC analysis and photocatalysis activity of RFeO3 orthoferrites (R = rare earth elements)","authors":"Mehrnoush Nakhaei , Marcos A.L. Nobre , Zahra Sabouri , Majid Darroudi , Davoud Sanavi Khoshnoud , Hossein Ali Khonakdar","doi":"10.1016/j.jmmm.2025.173736","DOIUrl":"10.1016/j.jmmm.2025.173736","url":null,"abstract":"<div><div>In this study, RFeO<sub>3</sub> nanoparticles were synthesized by sol-gel method to investigate the magnetic and photocatalytic properties of these perovskites. The morphology of the samples were investigated by field emission scanning electron microscopy. Beside x-ray diffraction patterns showed the orthorhombic structure with <em>Pbnm</em> space group with no impurity. For magnetic study of the RFeO<sub>3</sub> nanoparticles (NPs) the field-cooled and zero-field-cooled measurements were used. For this magnetic measurement, a quantum design PPMS system is used. In this way, the spin reorientation temperature (<em>T</em><sub><em>SR</em></sub>) and Neel temperature (<em>T</em><sub><em>N</em></sub>) of the samples were extracted, too. Next, diffuse reflectance spectroscopy analysis was used to calculate the band gap energy (<em>E</em><sub><em>g</em></sub>) of the samples according to the Kubelka-Munk function. The calculated values determined that the <em>E</em><sub><em>g</em></sub> values became more by decreasing the ionic radius of the rare earth elements in RFeO<sub>3</sub> NPs. At last, the photocatalytic activity of the RFeO<sub>3</sub> NPs was studied by calculating the degradation of <em>methylene Blue</em> (<em>MB</em>) dye solution. Therefore, the results showed that LaFeO<sub>3</sub> NPs has the highest degradation percent ∼96 % in 120 min.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173736"},"PeriodicalIF":3.0,"publicationDate":"2025-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145682713","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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