Element-selective elastic properties of Fe₆₅Ni₃₅ Invar alloy and Fe₇₂Pt₂₈ alloy studied by extended X-ray absorption fine structure

Platinum‐Iron(II) Oxide Sites Directly Responsible for Preferential Carbon Monoxide Oxidation at Ambient Temperature: An Operando X‐ray Absorption Spectroscopy Study**

“…Fourier‐transformed Pt L 3 ‐edge EXAFS profile becomes asymmetric for the active PtFe−Al 2 O 3 ‐673‐100, which is confirmed to be associated with the formation of the Pt−Fe bond through the Pt L 3 ‐edge EXAFS fitting (Figure 5a,b; Figure S4; Table S5) [12, 28, 29] . Imaginary part of the Fourier‐transformed Pt L 3 ‐edge EXAFS for PtFe−Al 2 O 3 ‐673‐100 is similar to the one from alloyed reference Pt−Fe nanoparticles, not pure Fe 0 (Figure 5b).…”

“…Reduction under 5 % of hydrogen for inactive PtFe−Al 2 O 3 ‐673‐5 results in a first coordination shell peak at 1.5 Å similar to the Fe−O shell, whereas the use of 100 % hydrogen for active PtFe−Al 2 O 3 ‐673‐100 gives rise to the metallic iron shell at 2.2 Å, close to the position of the corresponding Fe−Fe shell for the Pt−Fe/C alloy reference (Figure 4). [28, 29] Oscillations of the imaginary part of the Fourier‐transformed Fe K‐edge EXAFS of PtFe−Al 2 O 3 ‐673‐100 align with that of the reference alloy and not pure Fe 0 (Figure 4b).…”

Visualization of the disordered structure of Fe-Ni Invar alloys by reverse monte carlo calculations

“…A cluster structure, which reproduces the experimental results of both EXAFS and XRD, was found by RMC calculation. By using conventional EXAFS analysis, element-dependent differences in the local structure have been reported (Yokoyama and Eguchi, 2011;Kousa et al, 2020;Yokoyama, 2021). However, it is typically difficult to distinguish the neighboring atoms to the X-ray absorbing atoms by conventional EXAFS analysis, because metal elements with close atomic numbers, such as Fe and Ni, give comparable scattering amplitudes of the photoelectrons.…”

“…However, reverse Monte Carlo (RMC) calculation with complementary data sets of extended X-ray absorption fine structure (EXAFS) and X-ray diffraction (XRD) is a useful method to visualize the atomic arrangement in disordered alloys. 10.3389/fmats.2022.954110 Ferromagnetic Fe-Ni disordered alloy is a suitable material to investigate the distortion of atomic arrangements by the magnetovolume effect (Yokoyama and Eguchi, 2011;Kousa et al, 2020;Yokoyama, 2021). The large magnetovolume effect of Fe-Ni alloys compresses the lattice with increasing temperature, which offsets normal thermal expansion and leads to the zero thermal expansion.…”

First Principles Theory of the Pressure Induced Invar Effect in FeNi Alloys

“…With the new theory came a newfound interest in the anomaly and several experiments were carried out to investigate its validity. A number of experiments have found results that are consistent with the noncollinear magnetism model [10][11][12], but other studies have found disagreements with the theory. [7,13] In one experiment stimulated by Ref.…”