Journal of Magnetism and Magnetic Materials最新文献_第10页

Role of nanoparticle shape on the critical size for quasi-uniform ordering: From spheres to cubes through superballs 纳米粒子形状对准均匀有序临界尺寸的影响：从球体到立方体再到超级球

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-12-10 DOI: 10.1016/j.jmmm.2025.173751

Iago López-Vázquez , David Serantes , Òscar Iglesias

The equilibrium states of single-domain magnetite nanoparticles (NPs) result from a subtle interplay between size, geometry, and magnetocrystalline anisotropy. In this work, we present a micromagnetic study of shape-controlled magnetite NPs using the superball geometry, which provides a continuous interpolation between spheres and cubes. By isolating the influence of shape, we analyze the transition from quasi-uniform (single-domain) to vortex-like states as particle size increases, revealing critical sizes that depend on the superball exponent

p

. Our simulations show that faceted geometries promote the stabilization of vortex states at larger sizes, with marked distortions in the vortex core structure. The inclusion of cubic magnetocrystalline anisotropy, representative of magnetite, further lowers the critical size and introduces preferential alignment along the [111] easy axes. For isotropic shapes, the critical size for this transition increases with p, ranging from 49 nm for spheres to 56 nm for cubes, in agreement with experimental trends. In contrast, the presence of slight particle elongation increases the critical size and induces another preferential alignment direction. These results demonstrate that even small deviations from sphericity or aspect ratio significantly alter the magnetic ordering and stability of equilibrium magnetic states.

单畴磁铁矿纳米颗粒（NPs）的平衡态是尺寸、几何形状和磁晶各向异性之间微妙的相互作用的结果。在这项工作中，我们提出了一种使用超球几何结构的形状控制磁铁矿NPs的微磁研究，它提供了球体和立方体之间的连续插值。通过隔离形状的影响，我们分析了随着颗粒尺寸的增加，从准均匀（单畴）到涡状状态的转变，揭示了依赖于超级球指数p的临界尺寸。我们的模拟表明，多面几何形状促进了大尺寸涡旋状态的稳定，在涡旋核心结构中有明显的扭曲。以磁铁矿为代表的立方磁晶各向异性的加入，进一步降低了临界尺寸，并引入了沿易轴[111]的优先排列。对于各向同性形状，这种转变的临界尺寸随着p的增加而增加，范围从球体的49 nm到立方体的56 nm，与实验趋势一致。相反，微小颗粒伸长的存在增加了临界尺寸并诱导了另一个优先取向方向。这些结果表明，即使球度或纵横比的微小偏差也会显著改变磁有序和平衡磁态的稳定性。

{"title":"Role of nanoparticle shape on the critical size for quasi-uniform ordering: From spheres to cubes through superballs","authors":"Iago López-Vázquez , David Serantes , Òscar Iglesias","doi":"10.1016/j.jmmm.2025.173751","DOIUrl":"10.1016/j.jmmm.2025.173751","url":null,"abstract":"<div><div>The equilibrium states of single-domain magnetite nanoparticles (NPs) result from a subtle interplay between size, geometry, and magnetocrystalline anisotropy. In this work, we present a micromagnetic study of shape-controlled magnetite NPs using the superball geometry, which provides a continuous interpolation between spheres and cubes. By isolating the influence of shape, we analyze the transition from quasi-uniform (single-domain) to vortex-like states as particle size increases, revealing critical sizes that depend on the superball exponent <span><math><mi>p</mi></math></span>. Our simulations show that faceted geometries promote the stabilization of vortex states at larger sizes, with marked distortions in the vortex core structure. The inclusion of cubic magnetocrystalline anisotropy, representative of magnetite, further lowers the critical size and introduces preferential alignment along the [111] easy axes. For isotropic shapes, the critical size for this transition increases with p, ranging from 49 nm for spheres to 56 nm for cubes, in agreement with experimental trends. In contrast, the presence of slight particle elongation increases the critical size and induces another preferential alignment direction. These results demonstrate that even small deviations from sphericity or aspect ratio significantly alter the magnetic ordering and stability of equilibrium magnetic states.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173751"},"PeriodicalIF":3.0,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733824","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}

引用次数: 0

Effect of cyclic loading on the magnetic properties of FeCo-2V alloy 循环加载对FeCo-2V合金磁性能的影响

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-12-10 DOI: 10.1016/j.jmmm.2025.173752

Sirapob Toyting , Christopher W. Harrison , Stefan Michalik , Alexis Lambourne , Howard J. Stone

FeCo-2V soft magnetic alloys offer attractive properties for demanding electromagnetic applications. While their magnetic properties are well-characterised under static loading conditions, the evolution of these properties under cyclic mechanical loading, as seen in service, remains insufficiently explored. This study examines how fatigue deformation alters the magnetic behaviour of an FeCo-2V alloy. The investigation employed strain-controlled cyclic loading combined with Single Sheet Tester measurements across multiple frequencies. A modified Bertotti loss separation analysis quantified the contributions of hysteresis and eddy current losses to total core loss. Experimental results demonstrated an increase in coercivity, and significant core loss increase during early-stage fatigue, followed by more gradual changes at higher cycle counts. The abrupt initial property changes correlate with rapid dislocation accumulation, while subsequent stabilisation reflects saturated defect densities. Notably, hysteresis losses dominated the degradation, while eddy current losses remained stable throughout cycling. These findings establish clear relationships between cyclic loading and magnetic properties in FeCo-2V and may serve as the basis for non-destructive fatigue assessment through magnetic measurements.

FeCo-2V软磁合金为要求苛刻的电磁应用提供了诱人的性能。虽然它们的磁性在静态载荷条件下具有良好的特征，但在循环机械载荷下这些特性的演变，如在使用中所见，仍然没有得到充分的探索。本研究考察了疲劳变形如何改变FeCo-2V合金的磁性行为。该研究采用应变控制循环加载结合单片测试仪测量跨多个频率。改进的Bertotti损耗分离分析量化了磁滞和涡流损耗对铁芯总损耗的贡献。实验结果表明，矫顽力增加，岩心损失在早期疲劳期间显著增加，随后在更高的循环次数下变化更为平缓。突然的初始性能变化与快速的位错积累有关，而随后的稳定反映了饱和缺陷密度。值得注意的是，迟滞损耗主导了退化，而涡流损耗在整个循环过程中保持稳定。这些发现建立了循环载荷与FeCo-2V磁性之间的明确关系，并可作为通过磁性测量进行无损疲劳评估的基础。

{"title":"Effect of cyclic loading on the magnetic properties of FeCo-2V alloy","authors":"Sirapob Toyting , Christopher W. Harrison , Stefan Michalik , Alexis Lambourne , Howard J. Stone","doi":"10.1016/j.jmmm.2025.173752","DOIUrl":"10.1016/j.jmmm.2025.173752","url":null,"abstract":"<div><div>FeCo-2V soft magnetic alloys offer attractive properties for demanding electromagnetic applications. While their magnetic properties are well-characterised under static loading conditions, the evolution of these properties under cyclic mechanical loading, as seen in service, remains insufficiently explored. This study examines how fatigue deformation alters the magnetic behaviour of an FeCo-2V alloy. The investigation employed strain-controlled cyclic loading combined with Single Sheet Tester measurements across multiple frequencies. A modified Bertotti loss separation analysis quantified the contributions of hysteresis and eddy current losses to total core loss. Experimental results demonstrated an increase in coercivity, and significant core loss increase during early-stage fatigue, followed by more gradual changes at higher cycle counts. The abrupt initial property changes correlate with rapid dislocation accumulation, while subsequent stabilisation reflects saturated defect densities. Notably, hysteresis losses dominated the degradation, while eddy current losses remained stable throughout cycling. These findings establish clear relationships between cyclic loading and magnetic properties in FeCo-2V and may serve as the basis for non-destructive fatigue assessment through magnetic measurements.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173752"},"PeriodicalIF":3.0,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145787261","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}

引用次数: 0

Optimization of absorption properties of M-type calcium-chromium ferrite: Influence rules of chelating agent types and dosages m型钙铬铁氧体吸附性能的优化：螯合剂种类和用量的影响规律

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-12-09 DOI: 10.1016/j.jmmm.2025.173750

Li Zhuomin, Ma Zhijun, Weng Xingyuan, Zheng Yunsheng, Qin Ying, Xing Huiling

With the rapid development of electronic information and the intensification of electromagnetic pollution, the research focus in the field of electromagnetic shielding materials has shifted to the development of electromagnetic wave absorbing materials that possess high loss, wide bandwidth, lightweight thin layers and low cost. This thesis will employ the sol-gel - self-propagating combustion process to prepare M-type calcium‑chromium ferrite (Ca_0.8Cr_0.2Fe₁₂O₁₉), and will focus on systematically analyzing the changes in the crystal structure, microscopic morphology and electromagnetic wave absorption properties of the samples in relation to different types and dosages of chelating agents. The results show that under the conditions of pH = 7, self-propagating combustion temperature of 200 °C, crystallization temperature of 950 °C, and crystallization time of 8 h, nano-sized hexagonal-phase calcium‑chromium ferrite with an average particle size of 70.273–76.786 nm was successfully prepared. When citric acid was used as the chelating agent and the molar ratio of citric acid to metal cations was 1:1, the optimal reflection loss was achieved (absorption layer thickness 3.5 mm, frequency 14.6 GHz, reflection loss −17.5 dB, effective absorption coverage rate in Ku band reached 62.5 %). This excellent broadband absorption property stems from the unique nano-heterogeneous structure of M-type calcium‑chromium ferrite and the synergistic effect of its multiple loss mechanisms.

随着电子信息的快速发展和电磁污染的加剧，电磁屏蔽材料领域的研究重点已转向开发高损耗、宽带宽、轻量薄层、低成本的电磁波吸收材料。本文将采用溶胶-凝胶-自传播燃烧法制备m型钙铬铁氧体（Ca0.8Cr0.2Fe12O19），重点系统分析不同类型和剂量螯合剂对样品晶体结构、微观形貌和电磁波吸收性能的影响。结果表明：在pH = 7、自蔓延燃烧温度为200℃、结晶温度为950℃、结晶时间为8 h的条件下，成功制备了平均粒径为70.273 ~ 76.786 nm的纳米六方相钙铬铁氧体。以柠檬酸为螯合剂，柠檬酸与金属阳离子的摩尔比为1:1时，获得了最佳的反射损耗（吸收层厚度3.5 mm，频率14.6 GHz，反射损耗- 17.5 dB， Ku波段有效吸收覆盖率达到62.5%）。这种优异的宽带吸收性能源于m型钙铬铁氧体独特的纳米非均相结构及其多种损耗机制的协同效应。

{"title":"Optimization of absorption properties of M-type calcium-chromium ferrite: Influence rules of chelating agent types and dosages","authors":"Li Zhuomin, Ma Zhijun, Weng Xingyuan, Zheng Yunsheng, Qin Ying, Xing Huiling","doi":"10.1016/j.jmmm.2025.173750","DOIUrl":"10.1016/j.jmmm.2025.173750","url":null,"abstract":"<div><div>With the rapid development of electronic information and the intensification of electromagnetic pollution, the research focus in the field of electromagnetic shielding materials has shifted to the development of electromagnetic wave absorbing materials that possess high loss, wide bandwidth, lightweight thin layers and low cost. This thesis will employ the sol-gel - self-propagating combustion process to prepare M-type calcium‑chromium ferrite (Ca<sub>0.8</sub>Cr<sub>0.2</sub>Fe<sub>12</sub>O<sub>19</sub>), and will focus on systematically analyzing the changes in the crystal structure, microscopic morphology and electromagnetic wave absorption properties of the samples in relation to different types and dosages of chelating agents. The results show that under the conditions of pH = 7, self-propagating combustion temperature of 200 °C, crystallization temperature of 950 °C, and crystallization time of 8 h, nano-sized hexagonal-phase calcium‑chromium ferrite with an average particle size of 70.273–76.786 nm was successfully prepared. When citric acid was used as the chelating agent and the molar ratio of citric acid to metal cations was 1:1, the optimal reflection loss was achieved (absorption layer thickness 3.5 mm, frequency 14.6 GHz, reflection loss −17.5 dB, effective absorption coverage rate in Ku band reached 62.5 %). This excellent broadband absorption property stems from the unique nano-heterogeneous structure of M-type calcium‑chromium ferrite and the synergistic effect of its multiple loss mechanisms.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"639 ","pages":"Article 173750"},"PeriodicalIF":3.0,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145760604","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}

引用次数: 0

Halide double perovskites: Unveiling spin-polarized electronic, optical, and magnetic features for cutting-edge devices 卤化物双钙钛矿：揭示尖端器件的自旋极化电子、光学和磁性特征

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-12-08 DOI: 10.1016/j.jmmm.2025.173748

Ahmad Ali , Mohannad Al-Hmoud , Banat Gul , Muhammad Salman Khan , Gulzar Khan , Ahmed lfseisi , Ayed M. Binzowaimil , Siti Maisarah Aziz , Faheem Abbas , Ashour M. Ahmed

Lead-free double halide perovskite materials are regarded as interesting and potentially useful materials for solar cells and optoelectronic applications. The electronic structure, magnetic, and optical features of the novel halide perovskites Cs₂XMoI₆ (X = K, Li, and Na) are calculated using first-principles approach. Cs₂NaMoI₆ has the highest negative cohesive and formation energies, illustrating its structural and thermodynamic stability. The stability of Cs₂AMoI₆ material improves as the A-site cation moves from K to Na. Cs₂NaMoI₆ has the greatest stiffness and mechanical strength of the three materials. Cs₂KMoI₆ demonstrates the most ductility and isotropic elastic behavior. The magnetic investigation reveals the ferromagnetic nature of these materials as supported by optimization stability curves in different phases. The optical properties in the range of 0 to 14.0 eV are calculated. Due to their refractive index and absorption range from visible to ultraviolet, these materials have the potential to be used in high-energy absorbent and photovoltaic applications.

无铅双卤化物钙钛矿材料被认为是太阳能电池和光电子应用的有趣和潜在的有用材料。利用第一性原理方法计算了新型卤化物钙钛矿Cs2XMoI6 （X = K、Li和Na）的电子结构、磁性和光学特征。Cs2NaMoI6具有最高的负聚能和形成能，说明其结构和热力学稳定性。随着a位阳离子从K向Na的迁移，Cs2AMoI6材料的稳定性提高。三种材料中，Cs2NaMoI6具有最大的刚度和机械强度。Cs2KMoI6表现出最好的延性和各向同性弹性行为。磁性研究揭示了这些材料的铁磁性，并得到了不同相的优化稳定性曲线的支持。计算了0 ~ 14.0 eV范围内的光学性质。由于其折射率和吸收范围从可见光到紫外线，这些材料有潜力用于高能吸收和光伏应用。

{"title":"Halide double perovskites: Unveiling spin-polarized electronic, optical, and magnetic features for cutting-edge devices","authors":"Ahmad Ali , Mohannad Al-Hmoud , Banat Gul , Muhammad Salman Khan , Gulzar Khan , Ahmed lfseisi , Ayed M. Binzowaimil , Siti Maisarah Aziz , Faheem Abbas , Ashour M. Ahmed","doi":"10.1016/j.jmmm.2025.173748","DOIUrl":"10.1016/j.jmmm.2025.173748","url":null,"abstract":"<div><div>Lead-free double halide perovskite materials are regarded as interesting and potentially useful materials for solar cells and optoelectronic applications. The electronic structure, magnetic, and optical features of the novel halide perovskites Cs<sub>2</sub>XMoI<sub>6</sub> (X = K, Li, and Na) are calculated using first-principles approach. Cs<sub>2</sub>NaMoI<sub>6</sub> has the highest negative cohesive and formation energies, illustrating its structural and thermodynamic stability. The stability of Cs<sub>2</sub>AMoI<sub>6</sub> material improves as the A-site cation moves from K to Na. Cs<sub>2</sub>NaMoI<sub>6</sub> has the greatest stiffness and mechanical strength of the three materials. Cs<sub>2</sub>KMoI<sub>6</sub> demonstrates the most ductility and isotropic elastic behavior. The magnetic investigation reveals the ferromagnetic nature of these materials as supported by optimization stability curves in different phases. The optical properties in the range of 0 to 14.0 eV are calculated. Due to their refractive index and absorption range from visible to ultraviolet, these materials have the potential to be used in high-energy absorbent and photovoltaic applications.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173748"},"PeriodicalIF":3.0,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733797","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}

引用次数: 0

Exploring the influence of rare-earth ions on the magnetic glass behavior in RE2NiMnO6 (RE = Nd, Eu, Gd & Y) double perovskites 探讨稀土离子对RE2NiMnO6 （RE = Nd, Eu, Gd & Y）双钙钛矿中磁性玻璃行为的影响

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-12-08 DOI: 10.1016/j.jmmm.2025.173749

Debasmita Bala , Venimadhav Adyam , Yugandhar Bitla , H.D. Yang , D. Chandrasekhar Kakarla , Krishnamurthy Jyothinagaram

This study presents clear experimental evidence for a re-entrant glassy state in RE₂NiMnO₆ (RE = Nd, Eu, Gd, & Y) double perovskites, thoroughly investigated via temperature-dependent AC susceptibility measurements across varying frequencies and magnetic fields. Our results reveal ferromagnetic transitions at 195 K (Nd₂NiMnO₆), 142 K (Eu₂NiMnO₆), and 126 K (Gd₂NiMnO₆), while Y₂NiMnO₆ shows a weaker FM-like transition near ∼79 K. Frequency-dependent ACS measurements revealed relative freezing temperature shifts (δT_f) ranging from 0.03 to 0.34, indicative of an intermediate regime that consistently points to cluster spin glass-like behavior in all examined compounds. The frequency variation of T_f was analyzed using standard dynamic scaling models: (i) Vogel–Fulcher (VF) and (ii) Critical slowing down model (i.e., Power law). The analysis yielded critical exponents between 4 and 12, with VF temperatures found to be comparable to the estimated activation energies, E_a/k_B for each RE-based double perovskite. The DC/AC field–superimposed ACS measurements followed the de Almeida–Thouless line, revealing strong anisotropy and a non–mean-field-type instability in magnetic relaxation. Magnetic frustration, arising from competing antiferromagnetic and ferromagnetic exchanges and amplified by anti-site or anti-phase disorder, produces an asymmetric magnetic response characteristic of glassy states. Interestingly, in Gd₂NiMnO₆, this glassy behavior exhibits a distinctive sensitivity to the driving AC field.

本研究为RE2NiMnO6 （RE = Nd, Eu, Gd, &； Y）双钙钛矿的再入玻璃态提供了明确的实验证据，并通过在不同频率和磁场下的温度相关交流磁化率测量进行了深入研究。我们的研究结果揭示了195 K （Nd2NiMnO6）、142 K （Eu2NiMnO6）和126 K （Gd2NiMnO6）下的铁磁跃迁，而Y2NiMnO6在~ 79 K附近表现出较弱的类氟铁磁跃迁。频率相关的ACS测量显示，相对冻结温度变化（δTf）范围为0.03至0.34，表明在所有被检测的化合物中，一个中间状态一致地指向团簇自旋玻璃样行为。使用标准动态缩放模型分析Tf的频率变化：(i) Vogel-Fulcher （VF）和（ii）临界慢化模型（即幂律）。分析得出的临界指数在4到12之间，VF温度与每个re基双钙钛矿的估计活化能Ea/kB相当。DC/AC场叠加ACS测量遵循de Almeida-Thouless线，显示出强各向异性和磁弛豫的非平均场型不稳定性。磁挫折产生于反铁磁和铁磁交换的竞争，并被反位序或反相无序放大，产生玻璃态的不对称磁响应特征。有趣的是，在Gd2NiMnO6中，这种玻璃化行为对驱动交流场表现出独特的敏感性。

{"title":"Exploring the influence of rare-earth ions on the magnetic glass behavior in RE2NiMnO6 (RE = Nd, Eu, Gd & Y) double perovskites","authors":"Debasmita Bala , Venimadhav Adyam , Yugandhar Bitla , H.D. Yang , D. Chandrasekhar Kakarla , Krishnamurthy Jyothinagaram","doi":"10.1016/j.jmmm.2025.173749","DOIUrl":"10.1016/j.jmmm.2025.173749","url":null,"abstract":"<div><div>This study presents clear experimental evidence for a re-entrant glassy state in RE<sub>2</sub>NiMnO<sub>6</sub> (RE = Nd, Eu, Gd, & Y) double perovskites, thoroughly investigated via temperature-dependent AC susceptibility measurements across varying frequencies and magnetic fields. Our results reveal ferromagnetic transitions at 195 K (Nd<sub>2</sub>NiMnO<sub>6</sub>), 142 K (Eu<sub>2</sub>NiMnO<sub>6</sub>), and 126 K (Gd<sub>2</sub>NiMnO<sub>6</sub>), while Y<sub>2</sub>NiMnO<sub>6</sub> shows a weaker FM-like transition near ∼79 K. Frequency-dependent ACS measurements revealed relative freezing temperature shifts (δ<em>T</em><sub>f</sub>) ranging from 0.03 to 0.34, indicative of an intermediate regime that consistently points to cluster spin glass-like behavior in all examined compounds. The frequency variation of <em>T</em><sub>f</sub> was analyzed using standard dynamic scaling models: (i) Vogel–Fulcher (VF) and (ii) Critical slowing down model (i.e., Power law). The analysis yielded critical exponents between 4 and 12, with VF temperatures found to be comparable to the estimated activation energies, <em>E</em><sub>a</sub>/<em>k</em><sub>B</sub> for each RE-based double perovskite. The DC/AC field–superimposed ACS measurements followed the de Almeida–Thouless line, revealing strong anisotropy and a non–mean-field-type instability in magnetic relaxation. Magnetic frustration, arising from competing antiferromagnetic and ferromagnetic exchanges and amplified by anti-site or anti-phase disorder, produces an asymmetric magnetic response characteristic of glassy states. Interestingly, in Gd<sub>2</sub>NiMnO<sub>6</sub>, this glassy behavior exhibits a distinctive sensitivity to the driving AC field.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173749"},"PeriodicalIF":3.0,"publicationDate":"2025-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733792","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}

引用次数: 0

Pressure-induced half-metallicity in MnPtGa: A first-principles study MnPtGa中压力诱导的半金属丰度：第一性原理研究

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-12-06 DOI: 10.1016/j.jmmm.2025.173747

Tasso Yattung , S.K. Mohanta , P.K. Swain

The pressure-dependent electronic properties of

C 1_{b}

ternary Heusler compound MnPtGa was studied based on Density Functional Theory. Structural optimization yields a lattice parameter of 6.09 Å at ambient pressure, close to the experimental value of 6.15 Å. At 0 GPa, MnPtGa possesses metallic characteristics with 58.48% spin polarization. Under applied pressures of 10, 20, 30, and 40 GPa, the compound exhibits indirect band gaps of 0.71, 0.49, 0.50, and 0.35 eV, respectively, in the spin-down channel, resulting in 100% spin polarization. The Curie temperature is 271.8 K at ambient pressure, decreasing under compression. Phonon dispersion shows no imaginary frequencies, and the elastic constants satisfy the Born–Huang criteria, confirming dynamical and mechanical stability. The compound is ductile and anisotropic under both ambient and elevated pressures. High peaks of conductivity and absorptivity were noted in the ultraviolet (UV) region, which is particularly relevant for optoelectronic applications. These results underscore MnPtGa’s potential for applications in spintronic and UV optoelectronic devices.

基于密度泛函理论研究了C1b三元Heusler化合物MnPtGa的压力相关电子性质。结构优化得到的环境压力下晶格参数为6.09 Å，接近实验值6.15 Å。在0 GPa下，MnPtGa具有58.48%的自旋极化率。在10、20、30和40 GPa的压力下，该化合物在自旋向下通道中分别表现出0.71、0.49、0.50和0.35 eV的间接带隙，产生100%的自旋极化。居里温度在环境压力下为271.8 K，在压缩条件下降低。声子色散没有虚频率，弹性常数满足Born-Huang准则，证实了系统的动力和力学稳定性。该化合物在环境压力和高压下均具有延展性和各向异性。在紫外（UV）区域发现了高的电导率和吸收率峰，这与光电应用特别相关。这些结果强调了MnPtGa在自旋电子和紫外光电器件中的应用潜力。

{"title":"Pressure-induced half-metallicity in MnPtGa: A first-principles study","authors":"Tasso Yattung , S.K. Mohanta , P.K. Swain","doi":"10.1016/j.jmmm.2025.173747","DOIUrl":"10.1016/j.jmmm.2025.173747","url":null,"abstract":"<div><div>The pressure-dependent electronic properties of <span><math><mrow><mi>C</mi><msub><mrow><mn>1</mn></mrow><mrow><mi>b</mi></mrow></msub></mrow></math></span> ternary Heusler compound MnPtGa was studied based on Density Functional Theory. Structural optimization yields a lattice parameter of 6.09 Å at ambient pressure, close to the experimental value of 6.15 Å. At 0 GPa, MnPtGa possesses metallic characteristics with 58.48% spin polarization. Under applied pressures of 10, 20, 30, and 40 GPa, the compound exhibits indirect band gaps of 0.71, 0.49, 0.50, and 0.35 eV, respectively, in the spin-down channel, resulting in 100% spin polarization. The Curie temperature is 271.8 K at ambient pressure, decreasing under compression. Phonon dispersion shows no imaginary frequencies, and the elastic constants satisfy the Born–Huang criteria, confirming dynamical and mechanical stability. The compound is ductile and anisotropic under both ambient and elevated pressures. High peaks of conductivity and absorptivity were noted in the ultraviolet (UV) region, which is particularly relevant for optoelectronic applications. These results underscore MnPtGa’s potential for applications in spintronic and UV optoelectronic devices.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"638 ","pages":"Article 173747"},"PeriodicalIF":3.0,"publicationDate":"2025-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733799","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}

引用次数: 0

Magnetostriction model for non-oriented silicon steel based on physicochemical parameters of alloying elements 基于合金元素理化参数的无取向硅钢磁致伸缩模型

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-12-06 DOI: 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

电机的铁芯振动与无取向硅钢的磁致伸缩有关。固有结构被认为是磁致伸缩的内在因素。为了有效识别影响磁致伸缩的关键特征组合，提出了一种基于特征筛选的磁致伸缩预测模型，包括相关性筛选、特征权重排序和递归特征选择。结果表明，造成磁致伸缩的主要特征是绝对电负性、第三电离能和电子亲和性。采用支持向量回归算法建立“关键特征组合-磁致伸缩”模型，R2达到0.98。除Mn和co外，Al、Ti、V等元素的掺杂使无取向硅钢的磁致伸缩性能增强，所建立的机器学习模型对商用和多组分高性能无取向硅钢的磁致伸缩预测具有良好的可靠性，在此基础上应用符号回归算法构建了磁致伸缩的数学表达式。本文提出的特征选择框架为预测硅钢材料的磁致伸缩提供了有价值的思路

{"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}

引用次数: 0

Experimental and theoretical approaches for thermomagnetic properties of CoFe-based flexible amorphous ribbons: shape anisotropy contribution 钴铁基柔性非晶带热磁性能的实验与理论研究：形状各向异性的贡献

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-12-05 DOI: 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 Co₆₇Fe₄Mo_1.5Si_16.5B₁₁ 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 (S_eff) value of around

1.23 μV / K

. For the Anomalous Nerst coefficient (

S_{ANE})

, which considers the reduced temperature on the Co-base ribbon, the value is around 0

.17 μV / K

. These results position Co₆₇Fe₄Mo_1.5Si_16.5B₁₁ amorphous ribbons as highly promising for thermal energy conversion and highly sensitive magnetic field detectors, among other applications.

钴基快速淬火非晶态带是研究反常能效应的良好模型材料。它们提供了一个有前途的平台来探索热能转化为电能的效率，特别是与其他样品几何形状相比。然而，磁各向异性对热磁特性的贡献对于提高未来技术应用的能量转换效率起着至关重要的作用。本研究利用反常能效应（ANE）研究了Co67Fe4Mo1.5Si16.5B11组成的柔性非晶态带，通过改变外磁场强度和角度以及热梯度强度，研究了其具有很强的面内形状磁各向异性。对其微观结构和形态特征进行了分析，并对其电学性能进行了评估，以阐明它们对热磁信号的各自贡献。还提出了一个简单的理论模型来预测平面内形状磁各向异性主导的系统的磁和热磁响应。实验得到的cofe基非晶带的有效ANE系数（Seff）约为1.23μV/K。对于考虑co基带上温度降低的反常Nerst系数（SANE），其值约为0.17μV/K。这些结果表明，Co67Fe4Mo1.5Si16.5B11非晶带在热能转换和高灵敏度磁场探测器等方面具有很大的应用前景。

{"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}

引用次数: 0

Air sintering of Y-doped Mn-Zn-Li ferrites at reduced temperatures: additive-assisted enhancement of magnetic properties 氧掺杂Mn-Zn-Li铁氧体在低温下的空气烧结：添加剂辅助增强磁性能

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-12-05 DOI: 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 Y_xLi_0.14Mn_0.4Zn_0.32Fe_2.14-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.

掺杂剂浓度和烧结添加剂之间复杂的相互作用决定了Mn-Zn铁氧体的结构和磁性行为，为高级应用提供了定制其性能的途径。本研究研究了Y3+取代的Mn-Zn-Li铁氧体的结构、微观结构和磁性能，该铁氧体是在相对较低的烧结温度（1100℃）下在空气中通过固态法合成的，并加入了多组分烧结添加剂（SiO2、CaO、TiO2和Bi2O3）。采用x射线衍射（XRD）、扫描电镜（SEM）、能量色散x射线能谱（EDS）、密度测量和振动样品磁强计（VSM）对标称成分为YxLi0.14Mn0.4Zn0.32Fe2.14-xO4 （x = 0-0.2）的样品进行了分析。XRD数据证实，在所有掺杂水平上，尖晶石相几乎都是纯的，并且由于Y3+的掺入，晶格逐渐膨胀。x = 0.025的组合物产生了最高的磁化强度（~ 60 emu/g）和最低的矫顽力（~ 19 Oe），突出了其在需要稳定磁响应和晶粒尺寸控制的应用中的潜力。这些发现表明，协同Y3+掺杂和添加剂辅助烧结可以有效地调节铁氧体微观结构和磁性柔软度，其中x = 0.2是下一代软磁陶瓷的优化成分。

{"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}

引用次数: 0

Effect of bentonite on thixotropy of magnetic fluid 膨润土对磁流体触变性的影响

IF 3 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-12-05 DOI: 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.

触变性是流体流变学领域的一种独特现象。磁流体的触变行为通常很弱，在传统的流变学研究中经常被忽视。在这项研究中，流变仪与触变环法和三阶段触变法结合使用，系统地检查了四种不同的磁流体的触变特性，这些磁流体含有不同体积分数的膨润土（0%、8%、10%和12%）。重点分析了磁场强度和膨润土含量对这些流体触变性能的影响。结果表明，磁场强度对磁流体的触变性有显著影响，在外加磁场作用下，磁性颗粒形成了细长且更聚集的链状结构，从而增强了内部结构随时间的击穿和恢复。此外，膨润土的掺入显著改善了触变性能。在相同的磁场条件下，含膨润土磁流体的触变性回路面积明显大于不含膨润土的磁流体，且触变性随膨润土含量的增加而逐渐增大。具体来说，MF4（含12%膨润土）的触变性大约是MF1的3倍。这种增强来自于膨润土颗粒形成的三维网络与磁性颗粒的链状组合之间的协同相互作用，从而形成复合结构框架，增强了结构稳定性和恢复能力。综上所述，磁场强度和膨润土含量是调节磁流体触变行为的关键因素。这两个参数引起的协同结构效应为定制此类流体的触变特性提供了可行的方法，从而为其实际工程应用奠定了基础。

{"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}

引用次数: 0