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m?m?ssbauer spectroscopy studies on the particle size distribution effect of Fe–B–P amorphous alloy on the microwave absorption properties

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Nuclear Science and Techniques 2020年第3期31卷 61-70页

作者： Yu-Hua Lv Yan-Hui Zhang Jian Zhang Bin Li School of materials Science and Engineering Key Laboratory for Anisotropy and Texture of Materials Ministry of Education Northeastern University State Key Laboratory of Rolling and Automation Northeastern University Institute of Advanced magnetic materials Hangzhou Dianzi University School of Life Sciences Huzhou University

An Fe-based nanocrystalline alloy powder is important for application in microwave absorption, and the particle size has a critical impact on the electromagnetic microwave parameters. Therefore, it is necessary to study further the effects of the particle size on such parameters and improve the microwave absorption performance of Febased nanocrystalline powers. In this study, Fe–B–P particles were prepared through a synthetic approach consisting of an aqueous chemical reduction and a ball milling treatment. We investigated the effects of ball milling on the microstructure and electromagnetic properties of Fe–B–P particles. The experimental results indicate that the Fe–B–P particles synthesized through an aqueous chemical reduction are amorphous spheres. Fe–B–P particles with an original particle size of 200–1200 nm can be milled into an irregular shape with the size reduced to \ 500 nm after0.5 h of ball milling, and subsequently, the particles become smaller with increases in the milling time, with traces of Fe2O3generated on the particle surface. The results of the m?ssbauer spectra show that a portion of the small particles demonstrate a superparamagnetic *** volume proportions of the superparamagnetic component increase from 13.1 to 15.8% as the treatment time increases. We measured the permittivity and permeability spectra of Fe–B–P particles within the frequency range of2–18 GHz. The reflection loss(RL) is-10 dB for an absorber thickness of 1.7–5.0 mm. The RLis-20 dB for an absorber thickness of 1.9–2.7 mm. The microwave absorption properties of samples with the same thickness are improved with an increase in the treatment time and are shifted to a higher frequency, which will broaden the bandwidth of the absorption as well.

关键词： Fe–B–P particles m?m?ssbauer spectroscopy microwave absorber properties

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Influence of cerium ions on structure-dependent magnetic properties of Ba-Sr m-type hexaferrite nanocrystals

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Journal of Rare Earths 2024年第2期42卷 364-372,I0005页

作者： Ram A.Pawar Sunil m.Patange P.m.Dighe Sher Singh meena Abdullah GAl-Sehemi mehboobali Pannipara Santosh S.Jadhav Department of Physics ArtsCommerce and Science CollegeAhmednagar413711MaharashtraIndia Department of Physics Shri Krishna MahavidyalayaGunjotiDistOsmanabad413606MaharashtraIndia Padmashri Vikhe Patil College of Arts Science and CommercePravaranagarA/P.Loni(Kd)Tal.RahataDistAhmednagar413713MaharashtraIndia Solid State Physics Division Bhabha Atomic Research CentreMumbai400085MaharashtraIndia Department of Chemistry King Khalid UniversityAbha61413Saudi Arabia Department of Physics D.S.M's ArtsCommerce and Science CollegeJintur431509MaharashtraIndia

The present study is a systematic effort to investigate the structure-sensitive magnetic parameters of Ce^(3+) substituted Ba-Sr hexaferrite nanocrystals chemically formulated as Ba_(0.5)Sr_(0.5)Ce_(x)Fe_(12-x)O_(19) where x=0.0-0.2 with Δx=*** hexaferrite powders were prepared using the sol-gel self-ignition route and structurally characterized by means of powder X-ray diffraction and Fourier transform infrared *** creation of the m-type hexaferrite phase within the synthesized samples was revealed from the Rietveld refinement of the X-ray *** occurrence of a secondary phase of CeO_(2) was revealed within the hexaferrites for the substitution,x> *** refined X-ray diffraction data were utilized to compute the lattice parameters,X-ray density,and lattice parameter *** crystal structure plotted from the refined XRD data reveals the occupancy of the ions at different lattice *** XPS data of the hexaferrite were analyzed to confirm the oxidation states of the constituent *** nanocrystalline nature of the hexaferrites was revealed from the crystallite sizes calculated using Scherer's *** analysis of FTIR spectra confirms that only a fraction of Ce^(3+)accommodated in the lattice and the remaining Ce content reside in the form of the CeO_(2) *** morphology of the hexaferrites was analyzed from the FESEm profiles of the ferrite *** magnetic behavior study was performed by analyzing the Curie temperature,hysteresis loops,and hyperfine interactions by means of susceptibility,V.S.m,and mom?ssbauer spectroscopy,*** hexaferrites with increasing coercivity,decreasing saturation magnetization,and decreasing Curie temperature are reported in the *** substituted Ce^(3+)ions inhibit the grain growth and create lattice imperfections giving rise to hexaferrites with tuned magnetic parameters suitable for different applications.

关键词： Ba-Sr hexaferrite Ce^(3+)substitution XPS Saturation magnetization Coercivity m?m?ssbauer spectroscopy

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magnetocaloric effect of LaFe_(11.35)Co_(0.6)Si_(1.05) alloy

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Rare metals 2022年第5期41卷 1563-1569页

作者： Piotr Gebara Institute of Physics Czestochowa University of Technology42-200 CzestochowaPoland

The aim of the present paper was to study the large magnetocaloric effect observed in LaFe_(11.35)Co_(0.6)Si_(1.05)alloy. X-ray diffraction(XRD) result reveals a coexistence of two crystalline phases: a dominant La(Fe,Si)_(13)-type and a minor a-Fe(Co,Si). It is confirmed by the möm?ssbauer spectroscopy and microstructural observations accompanied by an energy-dispersive spectroscopy(EDS) analysis. The value of the magnetic entropy changes(|S_(m)|) in the vicinity of the Curie temperature(TC= 268 K) was calculated using thermomagnetic maxwell relation, and it equals to 21.4 J·kg^(-1)·K^(-1) under the change in an external magnetic field of μ_(0)ΔH = 3T. The investigation of magnetic phase transition was carried out using the Landau theory, an analysis of the field dependences of the magnetic entropy change and universal scaling curve, revealing the second order of phase transition in the studied material.

关键词： X-ray diffraction m?m?ssbauer spectroscopy magnetocaloric effect

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The effect of neodymium substitution on the structural and magnetic properties of nickel ferrite

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Progress in Natural Science:materials International 2015年第3期25卷 215-221页

作者： ?srafil ?abiko?lu Levent Paral? Ondrej malina Petr Novak Josef Kaslik Jiri Tucek Jiri Pechousek Jakub Navarik Oldrich Schneeweiss Celal Bayar University Faculty of Arts&SciencesDepartment of Physics 45140 Muradiye Celal Bayar University Department of Electronics and Automation Regional Centre of Advanced Technologies and materials Department of Experimental Physics and Physical ChemistryFaculty of SciencePalacky University Institute of Physics of materials of the Academy of Sciences of the Czech Republic

Nickel ferrite Ni Fe2O4 is a typical soft magnetic ferrite with high electrical resistivity used as high frequency magnetic material. Neodymium(Nd3+) doped Ni Fe2O4 materials were fabricated using solid state reaction. The properties of the obtained material were investigated by X-Ray Diffraction(XRD), Scanning Electron microscope(SEm), Fourier-Transform Infrared spectroscopy(FT-IR), magnetic measurements on SQUID and m?m?ssbauer spectroscopy. It was found that the material consists of two different phases: Nd3+doped Ni Fet2O4and Nd Fe O3. The Nd3 ions occupy cation sites of the Ni Fe2O4 inverse spinel structure. NdFeO3 phase occurred when the level of Nd3+atoms exceed a percolation *** presence of both phases was confirmed by SEm observations. The m?ssbauer spectra analysis showed two sextets, which can be ascribed to iron atoms in tetrahedral and octahedral positions. From their intensities it is concluded that Nd3+occupies octahedral sites in the spinel structure of Ni Fe2O4, which were originally occupied by Ni2+.

关键词： NiFe2O4 Neodymium Solid-state reaction magnetic properties m?m?ssbauer spectroscopy

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Theoretical Review of mossbauer Effect,Hyperfine Interactions Parameters and the Valence Fluctuations in Eu Systems

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Journal of Applied mathematics and Physics 2019年第1期7卷 254-270页

作者： mahmoud Abdelrazek Ahmida Electrical Engineering Department The Higher Institute of Sciences and Technology Ajdabiya Libya

In this paper, an overview of the theory of mössbauer effect is covered, and the main hyperfine interactions parameters which affect the shape of the resultant mössbauer spectrum are explained and illustrated as well. In principle, mössbauer effect applies to any and all nuclides, but in practice, certain ideal properties are desirable;that is, the conditions for recoil-free emission and absorption of gamma rays must be optimized. Therefore, briefly discussed in this review, one of the most commonly used for practical and fundamental studies the 151Eu mössbauer isotope. Also, the intermediate valence phenomena and their theoretical treatments are briefly discussed.

关键词： m?m?ssbauer spectroscopy Resonant Absorption Recoil-Free Fraction 151Eu mossbauer Isotope Hyperfine Interactions Valence Fluctuations

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