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

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.

Hollow Spherical Superstructure of Carbon Nanosheets for Bifunctional Oxygen Reduction and Evolution Electrocatalysis

“…26,27 XRD analysis was performed to analyze the composition of the nanoparticles in FeCoNi/HCS. From the XRD pattern in Figure 2b, peaks of ternary face-centered cubic (fcc) alloys (for example, NiFe alloy, PDF#47-1417), 28,29 spinel-type oxides (CoFe 2 O 4 , PDF#03-0864; NiFe 2 O 4 , PDF#10-0325, and so forth) and metal(II) oxides (NiO, PDF#47-1049; CoO, PDF#48-1719, and so forth) can be found. The HRTEM image of FeCoNi/HCS (Figure 2c) also exhibits lattice fringes of different phases in a nanoparticle.…”

Aqueous phase semihydrogenation of alkynes over Ni–Fe bimetallic catalysts

“…In the Ni 2p 3/2 spectrum of the Ni 1 Fe 3 catalyst, two major fitted bands at 852.5 eV and 853.1 eV are respectively associated with the core levels of metallic Ni 0 and Ni 2+ states. 47,51,52 Analogously, Ni 1 Fe 1 and Ni Fe 1 catalysts also displayed XPS peaks for Ni 2p 3/2 with two fitted bands corresponding to the metallic Ni 0 (major) and Ni 2+ (minor) states (Fig. 2).…”

“…The prominent peak at 706.7 eV corresponds to the metallic Fe 0 , while peaks at 711.4 eV and 708.7 eV are associated with Fe 3+ and Fe 2+ species, respectively. 47,51,52 Therefore, the presence of peaks corresponding to Ni 0 and Fe 0 in the XPS spectra indicated the co-existence of both Ni and Fe in the bimetallic Ni 3 Fe 1 , Ni 1 Fe 1 and Ni 1 Fe 3 catalysts. It is evident from the XPS pattern that the metallic Fe 0 species are abundant in all the bimetallic Ni 3 Fe 1 , Ni 1 Fe 1 and Ni 1 Fe 3 catalysts, while easy reoxidation of Fe 0 species in air probably resulted in the formation of Fe 2+ /Fe 3+ species over the catalyst surface, 51,52 as also observed as a thin oxide coating in the TEM images of these bimetallic Ni-Fe catalysts.…”

Alloying and Phase Transformation of Fe/FeNi Core/Alloy Nanoparticles at High Temperatures

“…15 A number of nanostructured FeNi alloys have also been prepared or studied at the nanoscale. 12,[16][17][18][19][20][21][22][23] The different synthetic strategies and potential applications often overshadow the difficulty in understanding and predicting the alloying of FeNi at the nanoscale, where enhanced diffusion, 24 and improved mixing enthalpies [25][26][27] are contrasted with a higher contribution of surface energies and interfacial strain. 28 Taken together, it is still challenging to model and describe equilibrium alloy nano-structures.…”