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

On the calculation of magnetic losses on non-narrow toroidal ring specimen

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-15 DOI: 10.1016/j.jmmm.2025.172791

Nikolaus Trnka , André Schleicher , Ralf Werner

In this paper, the validity of the loss calculation for toroidal specimen with non-narrow cross-section is proven, using the Poynting theorem as well as vector fields in cylindrical coordinates. The proof is done without the assumption of homogeneous or averaged fields, which is used in literature, but does not apply in reality. It is shown, that eddy currents inside the specimen do not influence the magnetic field

H

at the surface, which thus can be expressed by the primary winding current. Hence, the surface integral of the Poynting vector can be split into a circular integral over the electric field

E

and a residual term proportional to the current. This leads to the key result, that the electromagnetic loss is proportional to the electric circulating voltage, which is physically measurable as the induced voltage of the secondary winding. Further it is shown that the calculation is also valid for strongly developed eddy currents and non-linear material behavior. As a result, the theoretical basis for loss measurements with non-narrow toroidal specimen is now given. In addition, two geometric border cases are shown in detail and a numeric 3D-Simulation is used to investigate the field quantities on the surface of the specimen for different geometries and frequencies.

{"title":"On the calculation of magnetic losses on non-narrow toroidal ring specimen","authors":"Nikolaus Trnka , André Schleicher , Ralf Werner","doi":"10.1016/j.jmmm.2025.172791","DOIUrl":"10.1016/j.jmmm.2025.172791","url":null,"abstract":"<div><div>In this paper, the validity of the loss calculation for toroidal specimen with non-narrow cross-section is proven, using the Poynting theorem as well as vector fields in cylindrical coordinates. The proof is done without the assumption of homogeneous or averaged fields, which is used in literature, but does not apply in reality. It is shown, that eddy currents inside the specimen do not influence the magnetic field <math><mi>H</mi></math> at the surface, which thus can be expressed by the primary winding current. Hence, the surface integral of the Poynting vector can be split into a circular integral over the electric field <math><mi>E</mi></math> and a residual term proportional to the current. This leads to the key result, that the electromagnetic loss is proportional to the electric circulating voltage, which is physically measurable as the induced voltage of the secondary winding. Further it is shown that the calculation is also valid for strongly developed eddy currents and non-linear material behavior. As a result, the theoretical basis for loss measurements with non-narrow toroidal specimen is now given. In addition, two geometric border cases are shown in detail and a numeric 3D-Simulation is used to investigate the field quantities on the surface of the specimen for different geometries and frequencies.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172791"},"PeriodicalIF":2.5,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098411","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}

引用次数: 0

Periodic micromagnetic finite element method

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-14 DOI: 10.1016/j.jmmm.2025.172776

Fangzhou Ai, Jiawei Duan, Vitaliy Lomakin

The periodic micromagnetic finite element method (PM-FEM) is introduced to solve periodic unit cell problems using the Landau–Lifshitz–Gilbert equation. PM-FEM is applicable to general problems with 1D, 2D, and 3D periodicities. PM-FEM is based on a nonperiodic FEM-based micromagnetic solver and extends it in several aspects to account for periodicities, including the computation of exchange and magnetostatic fields. For the exchange field, PM-FEM modifies the sparse matrix construction for computing the Laplace operator to include additional elements arising due to the periodicities. For the magnetostatic field, the periodic extensions include modifications in the local operators, such as gradient, divergence, and surface magnetic charges, as well as the long-range superposition operator for computing the periodic scalar potential. The local operators are extended to account for the periodicities similar to handling the Laplace operator. For the long-range superposition operator, PM-FEM utilizes a periodic Green’s function (PGF) and fast spatial convolutions. The PGF is computed rapidly via exponentially rapidly convergent sums. The spatial convolutions are accomplished via a modified fast Fourier transform based adaptive integral method that allows calculating spatial convolutions with nonuniform meshes in

O (N log N)

numerical operations. PM-FEM is implemented on CPU and GPU based computer architectures. PM-FEM allows efficiently handling cases of structures contained within the periodic unit cell touching or not touching its boundaries as well as structures that protrude beyond the unit cell boundaries. PM-FEM is demonstrated to have about the same or even higher performance than its parent nonperiodic code. The demonstrated numerical examples show the efficiency of PM-FEM for highly complex structures with 1D, 2D, and 3D periodicities.

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引用次数: 0

Investigation of structural, magnetic, and electronic properties of Co doped NdMnO3

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-12 DOI: 10.1016/j.jmmm.2025.172798

Farooq H. Bhat , G. Anjum , Jan Asifa , Tanveer A. Dar , Ravi Kumar , Manzoor A. Malik

Polycrystalline NdMn_1-xCo_xO₃ (x = 0.0, 0.3, 0.7) samples were synthesized utilizing the conventional ceramic method. The X - ray diffraction patterns subjected to Rietveld refinement uncover the single-phase orthorhombic crystal structure for all the samples. Temperature-dependent magnetization executed at 0.05 T and 1.0 T reveal the transition from ferromagnetic to paramagnetic phase at Curie temperature T_c (∼ 60–140 K). In all the samples, zero field cooled (ZFC) and field cooled (FC) curves separate at thermo-magnetic irreversibility temperature (T_irr), except in x = 0.0 sample, at a higher field of 1 T. The ZFC curve displays the cusp showing maximum at temperature T_m. T_m and T_irr shift to lower temperatures with a broad maximum in ZFC as the external field is increased in x = 0.3 & 0.7 samples indicating ferromagnetic ordering. At a temperature of 10 K, magnetization versus magnetic field (M−H) curves undoubtedly imply the ferromagnetic interactions at low fields up to 3 T, and at fields greater than 3 T a distinctive antiferromagnetic character is evident that is pronounced in x = 0.7 sample. At T = 150 K, the M−H curve indicates paramagnetic behavior in x = 0.0 & 0.7 samples; however, in x = 0.3 sample, a slight non-linearity suggests feeble ferromagnetic interactions at tiny fields typically below 1 T.

The detailed analysis of X-ray absorption spectroscopy (XAS) spectra at L_3,2- edges of manganese (Mn) and cobalt (Co) ions along with O K-edge reveal that Mn exhibits mixed valent states i.e. Mn ³⁺/Mn⁴⁺ and Co shows high spin Co²⁺ and high/low spin Co³⁺ state. These results are confirmed using charge transfer multiplet calculations done at L_3,2 edges of Mn and Co ions. X-ray photoelectron spectroscopy (XPS) conducted at Mn2p, Co2p, and O1s −edges serves to reinforce and validate the XAS results.

{"title":"Investigation of structural, magnetic, and electronic properties of Co doped NdMnO3","authors":"Farooq H. Bhat , G. Anjum , Jan Asifa , Tanveer A. Dar , Ravi Kumar , Manzoor A. Malik","doi":"10.1016/j.jmmm.2025.172798","DOIUrl":"10.1016/j.jmmm.2025.172798","url":null,"abstract":"<div><div>Polycrystalline NdMn1-xCoxO3 (x = 0.0, 0.3, 0.7) samples were synthesized utilizing the conventional ceramic method. The X - ray diffraction patterns subjected to Rietveld refinement uncover the single-phase orthorhombic crystal structure for all the samples. Temperature-dependent magnetization executed at 0.05 T and 1.0 T reveal the transition from ferromagnetic to paramagnetic phase at Curie temperature Tc (∼ 60–140 K). In all the samples, zero field cooled (ZFC) and field cooled (FC) curves separate at thermo-magnetic irreversibility temperature (Tirr), except in x = 0.0 sample, at a higher field of 1 T. The ZFC curve displays the cusp showing maximum at temperature Tm. Tm and Tirr shift to lower temperatures with a broad maximum in ZFC as the external field is increased in x = 0.3 & 0.7 samples indicating ferromagnetic ordering. At a temperature of 10 K, magnetization versus magnetic field (M−H) curves undoubtedly imply the ferromagnetic interactions at low fields up to 3 T, and at fields greater than 3 T a distinctive antiferromagnetic character is evident that is pronounced in x = 0.7 sample. At T = 150 K, the M−H curve indicates paramagnetic behavior in x = 0.0 & 0.7 samples; however, in x = 0.3 sample, a slight non-linearity suggests feeble ferromagnetic interactions at tiny fields typically below 1 T.</div><div>The detailed analysis of X-ray absorption spectroscopy (XAS) spectra at L3,2- edges of manganese (Mn) and cobalt (Co) ions along with O K-edge reveal that Mn exhibits mixed valent states i.e. Mn 3+/Mn4+ and Co shows high spin Co2+ and high/low spin Co3+ state. These results are confirmed using charge transfer multiplet calculations done at L3,2 edges of Mn and Co ions. X-ray photoelectron spectroscopy (XPS) conducted at Mn2p, Co2p, and O1s −edges serves to reinforce and validate the XAS results.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172798"},"PeriodicalIF":2.5,"publicationDate":"2025-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098410","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

Weak low-temperature ferromagnetism and linear magnetoresistance in Lu0.75Fe6Sn6 with a disordered HfFe6Ge6-type structure

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-11 DOI: 10.1016/j.jmmm.2025.172793

Chenfei Shi , Zhaodi Lin , Qiyuan Liu , Junai Lyu , Xiaofan Xu , Baojuan Kang , Jin-Hu Yang , Yi Liu , Jian Zhang , Shixun Cao , Jin-Ke Bao

We report the synthesis of Lu_0.75Fe₆Sn₆ single crystals with a Fe-kagome lattice using a self-flux method. The crystal structure, magnetic, thermodynamic and electrical transport properties were investigated. Structure refinement reveals that Lu_0.75Fe₆Sn₆ has a HfFe₆Ge₆-type structure as the major framework intergrown with a CoSn-type structure, leading to a vacancy of 25 % on the Lu-site and disorder on the Sn-site. It exhibits a significant magnetic anisotropy with weak ferromagnetism in the ab-plane below 40 K and antiferromagnetic behavior along the c-axis. The weak ferromagnetism is due to the canted antiferromagnetism with magnetic moment deviating from the c-axis to the ab-plane. Besides, an anisotropic non-saturated linear magnetoresistance is also observed in Lu_0.75Fe₆Sn₆, probably resulting from the structural disorder in the sample.

{"title":"Weak low-temperature ferromagnetism and linear magnetoresistance in Lu0.75Fe6Sn6 with a disordered HfFe6Ge6-type structure","authors":"Chenfei Shi , Zhaodi Lin , Qiyuan Liu , Junai Lyu , Xiaofan Xu , Baojuan Kang , Jin-Hu Yang , Yi Liu , Jian Zhang , Shixun Cao , Jin-Ke Bao","doi":"10.1016/j.jmmm.2025.172793","DOIUrl":"10.1016/j.jmmm.2025.172793","url":null,"abstract":"<div><div>We report the synthesis of Lu0.75Fe6Sn6 single crystals with a Fe-kagome lattice using a self-flux method. The crystal structure, magnetic, thermodynamic and electrical transport properties were investigated. Structure refinement reveals that Lu0.75Fe6Sn6 has a HfFe6Ge6-type structure as the major framework intergrown with a CoSn-type structure, leading to a vacancy of 25 % on the Lu-site and disorder on the Sn-site. It exhibits a significant magnetic anisotropy with weak ferromagnetism in the ab-plane below 40 K and antiferromagnetic behavior along the c-axis. The weak ferromagnetism is due to the canted antiferromagnetism with magnetic moment deviating from the c-axis to the ab-plane. Besides, an anisotropic non-saturated linear magnetoresistance is also observed in Lu0.75Fe6Sn6, probably resulting from the structural disorder in the sample.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172793"},"PeriodicalIF":2.5,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098413","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

Microstructure, electrical resistivity, and magnetic properties of Fe-rich Sm(Co0.66-xSixFe0.25Cu0.065Zr0.025)7.8 magnets

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-10 DOI: 10.1016/j.jmmm.2025.172789

Rui Xia , Mingxiao Zhang , Ruixia Hou , Chaoqun Zhu , Dongliang Tan , Hangcheng Li , Chengxiong Liu , Haichen Wu , Zhuang Liu , Renjie Chen , Aru Yan

The effect of Si substitution for Co on the microstructure, electrical resistivity, and magnetic properties were systematically investigated in the Fe-rich Sm(Co_0.66-_xSi_xFe_0.25Cu_0.065Zr_0.025)_7.8 (x = 0–0.04) magnets. Minor Si substitution of x = 0.01 scarcely changes the constituent phases and microstructure in the magnets. With increasing x from 0.01 to 0.04, the Zr₆(Co,Fe,Si)₂₃ and Cu-rich impurity phases increase and the crystal grain becomes fine in the magnets gradually, accompanied by the incomplete cellular structure. Besides, the Si/Cu ratio in the cell boundary phase reaches a maximum value for the x = 0.01 magnet. As a result, the electrical resistivity at 27℃ monotonously increases from 81.9 µΩ·cm for x = 0 to 118.0 µΩ·cm for x = 0.04 in the direction perpendicular to the c-axis of the magnets. The vanishing of Zr-rich lamellar phase leads to an isotropy in electrical resistivity for x = 0.04. The similar relationship exists between electrical resistivity and Si substitution at 127℃ as well. The intrinsic coercivity of the magnets first slightly increases and then decreases with increasing Si content.

{"title":"Microstructure, electrical resistivity, and magnetic properties of Fe-rich Sm(Co0.66-xSixFe0.25Cu0.065Zr0.025)7.8 magnets","authors":"Rui Xia , Mingxiao Zhang , Ruixia Hou , Chaoqun Zhu , Dongliang Tan , Hangcheng Li , Chengxiong Liu , Haichen Wu , Zhuang Liu , Renjie Chen , Aru Yan","doi":"10.1016/j.jmmm.2025.172789","DOIUrl":"10.1016/j.jmmm.2025.172789","url":null,"abstract":"<div><div>The effect of Si substitution for Co on the microstructure, electrical resistivity, and magnetic properties were systematically investigated in the Fe-rich Sm(Co0.66-xSixFe0.25Cu0.065Zr0.025)7.8 (x = 0–0.04) magnets. Minor Si substitution of x = 0.01 scarcely changes the constituent phases and microstructure in the magnets. With increasing x from 0.01 to 0.04, the Zr6(Co,Fe,Si)23 and Cu-rich impurity phases increase and the crystal grain becomes fine in the magnets gradually, accompanied by the incomplete cellular structure. Besides, the Si/Cu ratio in the cell boundary phase reaches a maximum value for the x = 0.01 magnet. As a result, the electrical resistivity at 27℃ monotonously increases from 81.9 µΩ·cm for x = 0 to 118.0 µΩ·cm for x = 0.04 in the direction perpendicular to the c-axis of the magnets. The vanishing of Zr-rich lamellar phase leads to an isotropy in electrical resistivity for x = 0.04. The similar relationship exists between electrical resistivity and Si substitution at 127℃ as well. The intrinsic coercivity of the magnets first slightly increases and then decreases with increasing Si content.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"616 ","pages":"Article 172789"},"PeriodicalIF":2.5,"publicationDate":"2025-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143164781","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

Magnetic properties and large magnetocaloric effect in the amorphous RE2Co (RE = Tb, Dy, Er) ribbons

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-09 DOI: 10.1016/j.jmmm.2025.172779

Jiangbo Jia , Yusong Du , Xiaofei Wu , Xinqiang Gao , Lei Ma , Gang Cheng , Jiang Wang , Jingtai Zhao , Guanghui Rao

The microstructure, phase transition and magnetocaloric properties of RE₂Co (RE = Tb, Dy, Er) prepared by melt-spinning technology were studied. XRD and DSC confirmed the formation of RE₂Co (RE = Tb, Dy, Er) ribbons with amorphous nature. The DSC analysis results show that the first crystallization temperature of RE₂Co (RE = Tb, Dy, Er) amorphous alloys are 565 K, 590 K, and 644 K, respectively, while their melting temperatures are 972 K, 998 K, and 1066 K, indicating excellent thermal stability of the ribbon alloys. The RE₂Co (RE = Tb, Dy, Er) ribbons exhibit second-order ferromagnetic–paramagnetic transition at Curie temperatures of 92 K, 47 K, and 11 K, respectively. The RE₂Co (RE = Tb, Dy, Er) ribbons exhibit paramagnetic behavior consistent with Curie-Weiss law in the paramagnetic region, with paramagnetic Curie temperatures of 98 K, 54 K, and 3 K, respectively, where positive θ_p denotes the dominance of ferromagnetic contribution. For a magnetic field change of 0–5 T, the maximum magnetic entropy changes of RE₂Co (RE = Tb, Dy,) are 8.9 J/kg K and 7.8 J/kg K, respectively, with the corresponding refrigerant capacity values of 446.1 J/kg and 361.5 J/kg, while the maximum magnetic entropy change for Er₂Co is more than 27.1 J/kg K. The notable magnetocaloric effects indicate that the amorphous alloys RE₂Co (RE = Tb, Dy, Er) present promising potential as viable candidates for magnetic refrigeration applications at lower temperatures.

{"title":"Magnetic properties and large magnetocaloric effect in the amorphous RE2Co (RE = Tb, Dy, Er) ribbons","authors":"Jiangbo Jia , Yusong Du , Xiaofei Wu , Xinqiang Gao , Lei Ma , Gang Cheng , Jiang Wang , Jingtai Zhao , Guanghui Rao","doi":"10.1016/j.jmmm.2025.172779","DOIUrl":"10.1016/j.jmmm.2025.172779","url":null,"abstract":"<div><div>The microstructure, phase transition and magnetocaloric properties of RE2Co (RE = Tb, Dy, Er) prepared by melt-spinning technology were studied. XRD and DSC confirmed the formation of RE2Co (RE = Tb, Dy, Er) ribbons with amorphous nature. The DSC analysis results show that the first crystallization temperature of RE2Co (RE = Tb, Dy, Er) amorphous alloys are 565 K, 590 K, and 644 K, respectively, while their melting temperatures are 972 K, 998 K, and 1066 K, indicating excellent thermal stability of the ribbon alloys. The RE2Co (RE = Tb, Dy, Er) ribbons exhibit second-order ferromagnetic–paramagnetic transition at Curie temperatures of 92 K, 47 K, and 11 K, respectively. The RE2Co (RE = Tb, Dy, Er) ribbons exhibit paramagnetic behavior consistent with Curie-Weiss law in the paramagnetic region, with paramagnetic Curie temperatures of 98 K, 54 K, and 3 K, respectively, where positive θp denotes the dominance of ferromagnetic contribution. For a magnetic field change of 0–5 T, the maximum magnetic entropy changes of RE2Co (RE = Tb, Dy,) are 8.9 J/kg K and 7.8 J/kg K, respectively, with the corresponding refrigerant capacity values of 446.1 J/kg and 361.5 J/kg, while the maximum magnetic entropy change for Er2Co is more than 27.1 J/kg K. The notable magnetocaloric effects indicate that the amorphous alloys RE2Co (RE = Tb, Dy, Er) present promising potential as viable candidates for magnetic refrigeration applications at lower temperatures.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172779"},"PeriodicalIF":2.5,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098412","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

Synthesis and characterization of Ba0.8Ca0.2CoxZrxFe12-2xO19 by Sol-Gel Auto-Combustion route

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-09 DOI: 10.1016/j.jmmm.2025.172778

Sachin Kumar Godara , Mandeep Bhadan , Parth , Karan Arora , Suman , Parambir Singh Malhi , Varinder Kaur , Ashwani Kumar Sood , Jahangeer Ahmed , Asiya M. Tamboli , Pragati Kumar , Mandeep Singh

In the present study, Ba_0.8Ca_0.2Fe_12-2xCo_xZr_xO₁₉ (0.00 ≤ x ≤ 1.00) were manufactured by a sol–gel auto-combustion route (SGACR) and fabricated materials were calcined for 6 h at 900 °C. These Ba_0.8Ca_0.2Fe_12-2xCo_xZr_xO₁₉ (x = 0.00–1.00) were analyzed using different characterization techniques such as FTIR, XRD, VSM, Raman, and Impedance Analyzer. The X-ray diffractometer (XRD) data reveals that an intermediate phase (α-Fe₂O₃) was observed in x = 0.00. Secondary phases such as BaFe₂O₄, α/γ-Fe₂O_3, and BaCO₃ could not be detected in x = 0.20 to 1.00. The crystallite size monotonically decreases from 70.06 to 57.10 nm with an increment in Co-Zr content. Both lattice parameters enhanced with increment in dopant concentration because of large ionic radii of Zr⁴⁺ and Co²⁺. Raman peaks expand and intensity decreases with Zr⁴⁺ and Co²⁺ doping. The magnetic saturation values rise linearly with an enhancement in dopant concentration from x = 0.00 to 0.80 (M_s = 48.39–54.15 emu/g). A broadly inherent coercivity (H_c) in the extent 4858 Oe at (x = 0.00) to 1248 Oe at (x = 1.00) was analysed. The hard-permanent magnet-type material is transformed into soft magnetic recording materials with Zr⁴⁺ and Co²⁺ doping. The dielectric report clearly explains that (a) prime dielectric constant is recorded at curtail frequency (b) the greatest dielectric nature of the sample is exhibited at x = 0.80 and x = 1.00, and (c) further enhancement in enforced frequency leads to a reduction in dielectric constant. This synthesized material finds application in permanent magnets and EM shielding.

{"title":"Synthesis and characterization of Ba0.8Ca0.2CoxZrxFe12-2xO19 by Sol-Gel Auto-Combustion route","authors":"Sachin Kumar Godara , Mandeep Bhadan , Parth , Karan Arora , Suman , Parambir Singh Malhi , Varinder Kaur , Ashwani Kumar Sood , Jahangeer Ahmed , Asiya M. Tamboli , Pragati Kumar , Mandeep Singh","doi":"10.1016/j.jmmm.2025.172778","DOIUrl":"10.1016/j.jmmm.2025.172778","url":null,"abstract":"<div><div>In the present study, Ba0.8Ca0.2Fe12-2xCoxZrxO19 (0.00 ≤ x ≤ 1.00) were manufactured by a sol–gel auto-combustion route (SGACR) and fabricated materials were calcined for 6 h at 900 °C. These Ba0.8Ca0.2Fe12-2xCoxZrxO19 (x = 0.00–1.00) were analyzed using different characterization techniques such as FTIR, XRD, VSM, Raman, and Impedance Analyzer. The X-ray diffractometer (XRD) data reveals that an intermediate phase (α-Fe2O3) was observed in x = 0.00. Secondary phases such as BaFe2O4, α/γ-Fe2O3, and BaCO3 could not be detected in x = 0.20 to 1.00. The crystallite size monotonically decreases from 70.06 to 57.10 nm with an increment in Co-Zr content. Both lattice parameters enhanced with increment in dopant concentration because of large ionic radii of Zr4+ and Co2+. Raman peaks expand and intensity decreases with Zr4+ and Co2+ doping. The magnetic saturation values rise linearly with an enhancement in dopant concentration from x = 0.00 to 0.80 (Ms = 48.39–54.15 emu/g). A broadly inherent coercivity (Hc) in the extent 4858 Oe at (x = 0.00) to 1248 Oe at (x = 1.00) was analysed. The hard-permanent magnet-type material is transformed into soft magnetic recording materials with Zr4+ and Co2+ doping. The dielectric report clearly explains that (a) prime dielectric constant is recorded at curtail frequency (b) the greatest dielectric nature of the sample is exhibited at x = 0.80 and x = 1.00, and (c) further enhancement in enforced frequency leads to a reduction in dielectric constant. This synthesized material finds application in permanent magnets and EM shielding.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172778"},"PeriodicalIF":2.5,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097875","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

Hyperthermic response optimization for Mn0.5Zn0.5Fe2O4 magnetic fluid for its application in magnetic fluid hyperthermia

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-07 DOI: 10.1016/j.jmmm.2025.172777

Hima Patel, Kinnari Parekh

The present work reports the synthesis and characterization of Mn_0.5Zn_0.5Fe₂O₄ ferrite nanoparticles-based magnetic fluid for magnetic fluid hyperthermia. The synthesis of Mn_0.5Zn_0.5Fe₂O₄ is done using well-known co-precipitation, microwave, autoclave, and hydrothermal techniques. The XRD results confirm the pure and single-phase spinel structure for the samples synthesized using all the techniques. TEM images show the spherical shape of the particles in all four samples. All the samples are coated with polyethylene glycol as a surfactant to make the fluid biocompatible. The coating is confirmed by FTIR and TGA, whereas the stability of the magnetic fluids is measured by the zeta potential analyzer. The magnetic properties measured by VSM show that with the increase in the crystallinity and size of the samples, the domain magnetization of the particles increases. In the MFH, it is seen that the hyperthermia temperature window is successfully achieved when synthesized using a hydrothermal method. The results are discuss considering the improved crystallinity, size, saturation magnetization, and reduced polydispersity of the sample.

{"title":"Hyperthermic response optimization for Mn0.5Zn0.5Fe2O4 magnetic fluid for its application in magnetic fluid hyperthermia","authors":"Hima Patel, Kinnari Parekh","doi":"10.1016/j.jmmm.2025.172777","DOIUrl":"10.1016/j.jmmm.2025.172777","url":null,"abstract":"<div><div>The present work reports the synthesis and characterization of Mn0.5Zn0.5Fe2O4 ferrite nanoparticles-based magnetic fluid for magnetic fluid hyperthermia. The synthesis of Mn0.5Zn0.5Fe2O4 is done using well-known co-precipitation, microwave, autoclave, and hydrothermal techniques. The XRD results confirm the pure and single-phase spinel structure for the samples synthesized using all the techniques. TEM images show the spherical shape of the particles in all four samples. All the samples are coated with polyethylene glycol as a surfactant to make the fluid biocompatible. The coating is confirmed by FTIR and TGA, whereas the stability of the magnetic fluids is measured by the zeta potential analyzer. The magnetic properties measured by VSM show that with the increase in the crystallinity and size of the samples, the domain magnetization of the particles increases. In the MFH, it is seen that the hyperthermia temperature window is successfully achieved when synthesized using a hydrothermal method. The results are discuss considering the improved crystallinity, size, saturation magnetization, and reduced polydispersity of the sample.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172777"},"PeriodicalIF":2.5,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097870","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

Quantum mechanical design of rare-earth-free ferromagnetic material incorporating 2p element doping for permanent magnet applications

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-07 DOI: 10.1016/j.jmmm.2025.172775

Md Abdul Wahed , Chang-Dong Yeo , Yang-Ki Hong , Minyeong Choi , Shuhui Li , Woo-Young Lee , Seok Bae , Haein Choi-Yim

This study investigates the magnetic properties of non-rare-earth ferromagnetic materials, L1₀-ordered FeNi, Fe₂Ni₂N, and Fe₂Ni₂B, using the Kohn-Sham (KS) equation, mean field theory (MFT), Brillouin function (BF), and Callen-Callen (CC) semiempirical relation. We obtained electronic structures, electron density maps, and magnetocrystalline anisotropy energy (MAE) from first-principles calculations. The Curie temperature (T_C) was determined using MFT, while the thermomagnetic properties of L1₀-ordered FeNi and tetragonally ordered Fe₂Ni₂N and Fe₂Ni₂B were obtained from the BF and CC relation. The crystal structure and electron density map for L1₀-ordered FeNi have identified the interstitial sites for the 2p element doping. The addition of interstitial nitrogen (N) has decreased the c/a ratio to 0.992 from 1.007 and saturation magnetization (μ₀M_S) to 1.35 from 1.67T at 0 K. However, nitrogen doping has led to a significant increase in the magnetocrystalline anisotropy constant (K_u) to 1.94 from 0.47MJ/m³, while lowering T_C from 908 to 634 K. Boron (B) doping resulted in an even higher K_u of 2.75MJ/m³ at 0 K. The μ₀M_S for Fe₂Ni₂N is 1.20T (36 MGOe) at 300 K and 0.97T at 450 K. For Fe₂Ni₂B, the μ₀M_S is 0.97T (23 MGOe) at 300 K and 0.74T at 450 K. Fe₂Ni₂N demonstrates a higher saturation magnetization compared to commercial Sm-Co and Alnico, suggesting its potential as a non-rare-earth permanent magnet, filling the 10–30 MGOe gap in magnets. Our computational analysis indicates that B-doped FeNi has the potential to be a high-energy anisotropy permanent magnet with a significant hardness parameter κ of 1.67.

{"title":"Quantum mechanical design of rare-earth-free ferromagnetic material incorporating 2p element doping for permanent magnet applications","authors":"Md Abdul Wahed , Chang-Dong Yeo , Yang-Ki Hong , Minyeong Choi , Shuhui Li , Woo-Young Lee , Seok Bae , Haein Choi-Yim","doi":"10.1016/j.jmmm.2025.172775","DOIUrl":"10.1016/j.jmmm.2025.172775","url":null,"abstract":"<div><div>This study investigates the magnetic properties of non-rare-earth ferromagnetic materials, L10-ordered FeNi, Fe2Ni2N, and Fe2Ni2B, using the Kohn-Sham (KS) equation, mean field theory (MFT), Brillouin function (BF), and Callen-Callen (CC) semiempirical relation. We obtained electronic structures, electron density maps, and magnetocrystalline anisotropy energy (MAE) from first-principles calculations. The Curie temperature (TC) was determined using MFT, while the thermomagnetic properties of L10-ordered FeNi and tetragonally ordered Fe2Ni2N and Fe2Ni2B were obtained from the BF and CC relation. The crystal structure and electron density map for L10-ordered FeNi have identified the interstitial sites for the 2p element doping. The addition of interstitial nitrogen (N) has decreased the c/a ratio to 0.992 from 1.007 and saturation magnetization (μ0MS) to 1.35 from 1.67T at 0 K. However, nitrogen doping has led to a significant increase in the magnetocrystalline anisotropy constant (Ku) to 1.94 from 0.47MJ/m3, while lowering TC from 908 to 634 K. Boron (B) doping resulted in an even higher Ku of 2.75MJ/m3 at 0 K. The μ0MS for Fe2Ni2N is 1.20T (36 MGOe) at 300 K and 0.97T at 450 K. For Fe2Ni2B, the μ0MS is 0.97T (23 MGOe) at 300 K and 0.74T at 450 K. Fe2Ni2N demonstrates a higher saturation magnetization compared to commercial Sm-Co and Alnico, suggesting its potential as a non-rare-earth permanent magnet, filling the 10–30 MGOe gap in magnets. Our computational analysis indicates that B-doped FeNi has the potential to be a high-energy anisotropy permanent magnet with a significant hardness parameter κ of 1.67.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"615 ","pages":"Article 172775"},"PeriodicalIF":2.5,"publicationDate":"2025-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143097871","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

Theoretical study of transient nonlinear magnetic field simulation by a complex frequency domain finite element method with Laplace transform

IF 2.5 3区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY

Journal of Magnetism and Magnetic Materials

Pub Date : 2025-01-06 DOI: 10.1016/j.jmmm.2024.172765

Shengze Gao , Xiaojun Zhao , Yanhui Gao , Kazuhiro Muramatsu

A complex frequency domain finite element (FE) method is proposed to simulate transient nonlinear magnetic fields. In this method, the transient exciting signal is converted into the complex frequency domain by the Laplace transform and discretized by limited numbers of the considered harmonic orders. With the implementation of the fixed-point technique and the secant method, the algorithm is applicable for the computation of nonlinear magnetization. Besides, it is found that the value of the damping factor of the Laplace transform is sensitive to the convergence and the accuracy of this complex frequency domain method. Thus, a numerical technique optimally determining the damping factor is proposed and verified by comparing it to other strategies for setting the damping factor. As a validation, the simulation results of the proposed method are compared to the results of the time-stepping FE method and the harmonic balance (HB) FE method with Fourier transform using an eddy current model under the transient nonlinear magnetization. The results show that the proposed complex frequency domain method can accurately simulate the transient nonlinear magnetic field with a speed-up ratio of up to 4 to the time-stepping method in certain cases.

{"title":"Theoretical study of transient nonlinear magnetic field simulation by a complex frequency domain finite element method with Laplace transform","authors":"Shengze Gao , Xiaojun Zhao , Yanhui Gao , Kazuhiro Muramatsu","doi":"10.1016/j.jmmm.2024.172765","DOIUrl":"10.1016/j.jmmm.2024.172765","url":null,"abstract":"<div><div>A complex frequency domain finite element (FE) method is proposed to simulate transient nonlinear magnetic fields. In this method, the transient exciting signal is converted into the complex frequency domain by the Laplace transform and discretized by limited numbers of the considered harmonic orders. With the implementation of the fixed-point technique and the secant method, the algorithm is applicable for the computation of nonlinear magnetization. Besides, it is found that the value of the damping factor of the Laplace transform is sensitive to the convergence and the accuracy of this complex frequency domain method. Thus, a numerical technique optimally determining the damping factor is proposed and verified by comparing it to other strategies for setting the damping factor. As a validation, the simulation results of the proposed method are compared to the results of the time-stepping FE method and the harmonic balance (HB) FE method with Fourier transform using an eddy current model under the transient nonlinear magnetization. The results show that the proposed complex frequency domain method can accurately simulate the transient nonlinear magnetic field with a speed-up ratio of up to 4 to the time-stepping method in certain cases.</div></div>","PeriodicalId":366,"journal":{"name":"Journal of Magnetism and Magnetic Materials","volume":"614 ","pages":"Article 172765"},"PeriodicalIF":2.5,"publicationDate":"2025-01-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143156495","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