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Dependence of phase configurations, microstructures and magnetic properties of iron-nickel (Fe-Ni) alloy nanoribbons on deoxidization temperature in hydrogen

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ABSTRACT

Iron-nickel (Fe-Ni) alloy nanoribbons were reported for the first time by deoxidizing NiFe2O4 nanoribbons, which were synthesized through a handy route of electrospinning followed by air-annealing at 450 °C, in hydrogen (H2) at different temperatures. It was demonstrated that the phase configurations, microstructures and magnetic properties of the as-deoxidized samples closely depended upon the deoxidization temperature. The spinel NiFe2O4 ferrite of the precursor nanoribbons were firstly deoxidized into the body-centered cubic (bcc) Fe-Ni alloy and then transformed into the face-centered cubic (fcc) Fe-Ni alloy of the deoxidized samples with the temperature increasing. When the deoxidization temperature was in the range of 300 ~ 500 °C, although each sample possessed its respective morphology feature, all of them completely reserved the ribbon-like structures. When it was further increased to 600 °C, the nanoribbons were evolved completely into the fcc Fe-Ni alloy nanochains. Additionally, all samples exhibited typical ferromagnetism. The saturation magnetization (Ms) firstly increased, then decreased, and finally increased with increasing the deoxidization temperature, while the coercivity (Hc) decreased monotonously firstly and then basically stayed unchanged. The largest Ms (~145.7 emu·g−1) and the moderate Hc (~132 Oe) were obtained for the Fe-Ni alloy nanoribbons with a mixed configuration of bcc and fcc phases.

No MeSH data available.


(a) M-H loops of S0-S4 recorded at room temperature. (b) Ms and Hc of S1-S4 as functions of the deoxidization temperature. The insets in (a,b) show the expended views of M-H loops and the Hc as a function of the grain size (D), respectively.
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f5: (a) M-H loops of S0-S4 recorded at room temperature. (b) Ms and Hc of S1-S4 as functions of the deoxidization temperature. The insets in (a,b) show the expended views of M-H loops and the Hc as a function of the grain size (D), respectively.

Mentions: Figure 5(a) depicts the magnetization (M-H) loops of S0-S4 recorded at room temperature and the inset shows the corresponding enlarged views. It reveals that all samples exhibit typical ferromagnetic behaviors. For NiFe2O4 precursor nanoribbons (S0), the Ms and Hc are respectively about 45.1 emu·g−1 and 212 Oe. The hysteresis loops of the deoxidized S1-S4 closely vary with the deoxidization temperature. The largest Ms about 145.7 emu·g−1 is obtained for S2. For standard crystalline Fe and Ni, their magnetic moments per cell are about 2.2 μB and 0.6 μB1333, respectively. And the bulk Ms34 of bcc Fe is about 222 emu·g−1. Therefore, the bulk Ms of Fe67Ni33 can be approximately estimated to be about 167 emu·g−1, which is basically in constant with the reported value of 168 emu·g−1 in the literature3536. In our case, thus, the experimental value is very close to the estimated bulk value. The above investigations of XRD and XPS have indicated that a thin oxide shells present at the surface, in which the magnetic spins are disordered and pinned3738. This could account for the slight difference of Ms between our result and the calculated bulk value. On the other hand, except for S1, the Hc values of S2-S4 (pure Fe67Ni33) are all lower than 150 Oe. Based on the above results, hence, the Fe-Ni alloy nanoribbon is a considerable soft magnetic nanomaterial. Additionally, the most significant feature of the Fe-Ni alloy nanoribbons is their unique geometry of the ribbon-like structure self-assembled by NPs. Compared with the zero-dimensional alloy materials, Fe-Ni alloy nanoribbons have an amazing advantage is that they can be used in the miniaturizing and high density electronic components such as antennas and stealth devices. Therefore, the high-frequency properties can probably be a major future research content and direction.


Dependence of phase configurations, microstructures and magnetic properties of iron-nickel (Fe-Ni) alloy nanoribbons on deoxidization temperature in hydrogen
(a) M-H loops of S0-S4 recorded at room temperature. (b) Ms and Hc of S1-S4 as functions of the deoxidization temperature. The insets in (a,b) show the expended views of M-H loops and the Hc as a function of the grain size (D), respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5120276&req=5

f5: (a) M-H loops of S0-S4 recorded at room temperature. (b) Ms and Hc of S1-S4 as functions of the deoxidization temperature. The insets in (a,b) show the expended views of M-H loops and the Hc as a function of the grain size (D), respectively.
Mentions: Figure 5(a) depicts the magnetization (M-H) loops of S0-S4 recorded at room temperature and the inset shows the corresponding enlarged views. It reveals that all samples exhibit typical ferromagnetic behaviors. For NiFe2O4 precursor nanoribbons (S0), the Ms and Hc are respectively about 45.1 emu·g−1 and 212 Oe. The hysteresis loops of the deoxidized S1-S4 closely vary with the deoxidization temperature. The largest Ms about 145.7 emu·g−1 is obtained for S2. For standard crystalline Fe and Ni, their magnetic moments per cell are about 2.2 μB and 0.6 μB1333, respectively. And the bulk Ms34 of bcc Fe is about 222 emu·g−1. Therefore, the bulk Ms of Fe67Ni33 can be approximately estimated to be about 167 emu·g−1, which is basically in constant with the reported value of 168 emu·g−1 in the literature3536. In our case, thus, the experimental value is very close to the estimated bulk value. The above investigations of XRD and XPS have indicated that a thin oxide shells present at the surface, in which the magnetic spins are disordered and pinned3738. This could account for the slight difference of Ms between our result and the calculated bulk value. On the other hand, except for S1, the Hc values of S2-S4 (pure Fe67Ni33) are all lower than 150 Oe. Based on the above results, hence, the Fe-Ni alloy nanoribbon is a considerable soft magnetic nanomaterial. Additionally, the most significant feature of the Fe-Ni alloy nanoribbons is their unique geometry of the ribbon-like structure self-assembled by NPs. Compared with the zero-dimensional alloy materials, Fe-Ni alloy nanoribbons have an amazing advantage is that they can be used in the miniaturizing and high density electronic components such as antennas and stealth devices. Therefore, the high-frequency properties can probably be a major future research content and direction.

View Article: PubMed Central - PubMed

ABSTRACT

Iron-nickel (Fe-Ni) alloy nanoribbons were reported for the first time by deoxidizing NiFe2O4 nanoribbons, which were synthesized through a handy route of electrospinning followed by air-annealing at 450 °C, in hydrogen (H2) at different temperatures. It was demonstrated that the phase configurations, microstructures and magnetic properties of the as-deoxidized samples closely depended upon the deoxidization temperature. The spinel NiFe2O4 ferrite of the precursor nanoribbons were firstly deoxidized into the body-centered cubic (bcc) Fe-Ni alloy and then transformed into the face-centered cubic (fcc) Fe-Ni alloy of the deoxidized samples with the temperature increasing. When the deoxidization temperature was in the range of 300 ~ 500 °C, although each sample possessed its respective morphology feature, all of them completely reserved the ribbon-like structures. When it was further increased to 600 °C, the nanoribbons were evolved completely into the fcc Fe-Ni alloy nanochains. Additionally, all samples exhibited typical ferromagnetism. The saturation magnetization (Ms) firstly increased, then decreased, and finally increased with increasing the deoxidization temperature, while the coercivity (Hc) decreased monotonously firstly and then basically stayed unchanged. The largest Ms (~145.7 emu·g−1) and the moderate Hc (~132 Oe) were obtained for the Fe-Ni alloy nanoribbons with a mixed configuration of bcc and fcc phases.

No MeSH data available.