Hyperfine Interactions and Some Magnetic Properties of Nanocrystalline Co₄₀Fe₅₀Ni₁₀and Co₅₀Fe₄₅Ni₅Alloys Prepared by Mechanical Synthesis and Subsequently Heat Treated

Abstract

Co40Fe50Ni10 and Co50Fe45Ni5 ternary alloys were prepared by mechanical alloying method. To check the stability of their structure thermal treatment was applied subsequently. As X-ray diffraction studies proved the final products of milling were the solid solutions with bcc lattice and the average grain sizes ranged of tens of nanometers. After heating of the Co50Fe45Ni5 alloy up to 993 K the mixture of two solid solutions with bcc and fcc lattices was formed. In other cases thermal treatment did not change the type of the crystalline lattice. Mössbauer spectroscopy revealed hyperfine magnetic field distributions which reflected the different possible atomic surroundings of 57 Fe isotopes. Results of the macroscopic magnetic measurements proved that both investigated alloys had relatively good soft magnetic properties.

Direct Laser Writing of Multimetal Bifunctional Catalysts for Overall Water Splitting

“…Due to the heterogeneous nature, a range of lattice spacing measurements were recorded mostly falling within the 0.20–0.25 nm range. The 0.25 nm lattice measurement shown within the HRTEM inset in Figure falls within normal lattice spacing range for FCC FeCoNi alloys and FCC CrFeCoNi alloys for the (111) plane both before and after HER–OER catalytic testing. As observed in the XRD pattern, the 2θ shifts resemble the FCC CrFeCoNi alloy more closely (Figure S8c).…”

Single-Step Direct Laser Writing of Multimetal Oxygen Evolution Catalysts from Liquid Precursors

“…7,8,15 We found in XRD spectra that catalyst 2 shows higher intensity peaks overall than the peaks in catalyst 1's XRD spectra (Figure S9a and S10a), and therefore suggests a more overall crystalline structure in catalyst 2. We also found that the XRD diffraction peaks for catalyst 1 indicate a similar match to a ternary metal alloy reference of Fe0.5Co0.4Ni0.1, 34 while catalyst 2 indicates a similar match to a ternary metal alloy reference of Fe0.33Co0.48Ni0.19. 35 While neither catalyst showed metal oxide peaks before electrochemical testing, catalyst 1 exhibited low intensity NiO peaks 36 after electrochemical testing.…”

“…17,37 HRTEM measurements of the lattice spacing of the nanocrystalline particles (Figure S9b, S10b) yielded spacings of 0.20 nm for catalyst 1 and 0.18 nm for catalyst 2, which match well to their XRD (111) and ( 200) plane reference values respectively. 34,35 We analyzed both catalysts with STEM and EDS mapping after LSV and observed the presence of particles containing Fe, Ni, and Co (with higher amounts of Ni and Co compared to Fe), dispersed within a primarily iron oxide matrix (Figure 3a and Figure S9b, S10b). Catalyst 1 had particle sizes averaging ~10 nm in diameter (Figure 3a and Figure S11), while catalyst 2 had a more polydisperse particle size range of ~2-11 nm (Figure S9b and Figure S11).…”

“…To experimentally probe the importance of the amorphous matrix structure, we annealed catalyst 1 at temperatures between 100 and 400 °C under argon for an hour in an attempt to increase the crystallinity of the matrix and examine the effect on the catalytic performance (Figure S12). XRD spectra of the annealed samples (Figure S12a) indicate that indeed there was an increase of intensity in the crystalline metallic ternary alloy peaks and also the appearance of metallic iron peaks as a result of thermal annealing . We then conducted LSV on catalyst 1 annealed at different temperatures to determine the corresponding OER performance (Figure S12b).…”

Local atomic arrangement in mechanosynthesized Co x Fe1−x−y Ni y alloys studied by Mössbauer spectroscopy

“…The alloys were disordered solid solutions, characterized by the bcc, or fcc crystalline lattice of the regular system. Detailed structural investigations were presented earlier in works [23][24][25][26]. Figure 1a presents, as an example, room-temperature Mössbauer spectra for mechanosynthesized Co 40 Fe 40 Ni 20 system, recorded at various stages of milling process.…”