Saturation magnetization and Curie temperature of nanocrystalline nickel

Valiev, Ruslan Z.; Korznikova, G. F.; Mulyukov, Kh. Ya.; Mishra, Rajiv S.; Mukherjee, Asok K.

doi:10.1080/13642819708205708

Cited by 36 publications

(16 citation statements)

References 17 publications

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“…Most of them are available as powders, ribbons, and thin films and are used in a huge variety of industrial applications such as motors, generators, transformers, sensors, or microelectronic devices. Earlier investigations showed the strong influence of nanostructuring via SPD on magnetic hysteresis characteristics of soft magnetic metals, such as Ni [173,174], Co [175], Fe, and Fe-Si [176]. A sharp increase in the coercivity Hc was revealed in pure metals after SPD processing.…”

Section: Magnetic Propertiesmentioning

confidence: 96%

Multifunctional Properties of Bulk Nanostructured Metallic Materials

Sabirov

Enikeev

Murashkin

et al. 2015

Bulk Nanostructured Materials With Multifunctional Properties

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This chapter focuses on multifunctional properties of bulk nanostructured metallic materials and structure-properties relationship therein. The most important structural factors affecting mechanical, physical, and chemical properties of the nanomaterials are discussed, and the strategies to their further improvement are outlined. Special attention is paid to nanostructural design for simultaneous improvement of mutually exclusive properties. Superstrength and Enhanced Mechanical PropertiesAlthough the mechanical and functional properties of all polycrystalline metallic materials are determined by several factors, the grain size of the material generally plays the most significant and often a dominant role. Thus, the strength of different polycrystalline materials is related to the grain size, d, through the Hall-Petch equation which states that the yield stress, σ y , is given bywhere σ o is termed the friction stress and k y the Hall-Petch constant [1,2]. It follows from Eq. 3.1 that the strength increases with a reduction in the grain size and this has led to an ever-increasing interest in fabricating materials with extremely small grain sizes. The fabrication of bulk samples and billets using equal channel angular pressing (ECAP), high pressure torsion (HPT), and other severe plastic deformation (SPD) techniques was a crucial first step in initiating investigations into the properties of bulk nanomaterials because the use of SPD processing permitted, and subsequently fully supported, a series of systematic studies using various nanostructured metallic materials including commercial alloys [3][4][5][6][7][8]

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Section: Magnetic Propertiesmentioning

confidence: 96%

Multifunctional Properties of Bulk Nanostructured Metallic Materials

Sabirov

Enikeev

Murashkin

et al. 2015

Bulk Nanostructured Materials With Multifunctional Properties

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“…(18), can affect both the shape and area of the loop. For a given spontaneous magnetization m sp ¼ M sp /(aM s ), the corresponding temperature can be calculated by setting either h s rev or h s irr (depending on whether m sp occurs on a reversible or irreversible loop segment) to zero, and then solving for t. Whereas irreversible hysteresis loop segments are normally ignored in spontaneous-magnetization studies, we find that these are important when t approaches 1, since they can explain the "tail" or "foot" that has been observed experimentally, [12][13][14]18,29 theoretically in ferromagnetic Ising systems 30 and in micromagnetic simulations. 31 The literature contains several alternative explanations of these tails.…”

Section: Positive-feedback Model Of Spontaneous Magnetizationmentioning

confidence: 97%

“…35 Fig. 4 shows measured (T,m sp ) data 29,36 for bulk nickel, compared with the theoretical curve obtained using Eq. (22) for points on Rev loop segments (0 < t < s,) and Eq.…”

Section: A Nickelmentioning

confidence: 99%

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Calculating the spontaneous magnetization and defining the Curie temperature using a positive-feedback model

Harrison

2014

Journal of Applied Physics

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A positive-feedback mean-field modification of the classical Brillouin magnetization theory provides an explanation of the apparent persistence of the spontaneous magnetization beyond the conventional Curie temperature-the little understood "tail" phenomenon that occurs in many ferromagnetic materials. The classical theory is unable to resolve this apparent anomaly. The modified theory incorporates the temperature-dependent quantum-scale hysteretic and mesoscopic domain-scale anhysteretic magnetization processes and includes the effects of demagnetizing and exchange fields. It is found that the thermal behavior of the reversible and irreversible segments of the hysteresis loops, as predicted by the theory, is a key to the presence or absence of the "tails." The theory, which permits arbitrary values of the quantum spin number J, generally provides a quantitative agreement with the thermal variations of both the spontaneous magnetization and the shape of the hysteresis loop.

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“…Several preparation techniques have been employed so far in order to obtain a bulk material [severe plastic deformation (Zhilyaev et al, 2002, and references therein), ball milling (Bonetti et al, 1999;Valiev et al, 1997) or inert gas condensation followed by compaction of nanocrystalline powders (Birringer et al, 1984)], thick films [direct or pulsed electrodeposition (Shriram et al, 2000;Palumbo et al, 1997;El-Sherik & Erb, 1995)] or thin films [physical vapour deposition methods, PVD (Knapp & Follstaedt, 2004;Zhong et al, 2004;Brunetti & Monticone, 1993;Hugo et al, 2003;Mitra et al, 2001Mitra et al, , 2004Gai et al, 2002;Hurley et al, 2005)]. Among the PVD methods of ncNi production, magnetron sputtering has been relatively seldom employed for the preparation of nc-Ni (Brunetti & Monticone, 1993;Hugo et al, 2003;Mitra et al, 2001Mitra et al, , 2004Gai et al, 2002;Hurley et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Structural study of nanocrystalline nickel thin films

et al. 2007

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Nickel thin films (400 nm) were deposited by magnetron sputtering onto fused silica substrates. The effects of argon pressure and substrate temperature (from room temperature to 973 K) upon the film structure were investigated. The film structure was studied using grazing‐incidence small‐angle X‐ray scattering (GISAXS) and X‐ray diffraction (XRD) analysis. It was found that the prepared nanocrystalline Ni films contain two kinds of inhomogeneities observable by GISAXS, namely isotropic and platelet‐like. Up to about 373 K the isotropic or spherical `particles' prevail, while above that temperature the platelet‐like `particles' predominate. These inhomogeneities are ascribed to intergranular matter or grain boundaries, since the grain size (as determined from the XRD patterns) was found to increase from 7 nm in samples deposited at room temperature to about 90 nm in samples deposited at 423 K or higher temperature.

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Saturation magnetization and Curie temperature of nanocrystalline nickel

Cited by 36 publications

References 17 publications

Multifunctional Properties of Bulk Nanostructured Metallic Materials

Multifunctional Properties of Bulk Nanostructured Metallic Materials

Calculating the spontaneous magnetization and defining the Curie temperature using a positive-feedback model

Structural study of nanocrystalline nickel thin films

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