Variable Temperature 57Fe-Mössbauer Spectroscopy Study of Nanoparticle Iron Carbides

Abstract

Near-phase-pure nanoparticle iron carbides (Fe3C and Fe5C2) were synthesised. Debye model calculations were used with hyperfine parameters gathered by 57 Fe Mössbauer spectroscopy within a temperature range of 10 K to 293 K, with analysis providing Debye temperatures of 422 K and 364 K for two Fe sites in Fe5C2 and 355 K for ferromagnetic Fe3C. The intrinsic isomer shifts were calculated as 0.45 mm s −1 and 0.43 mm s −1 for iron sites 1 and 2 respectively in Fe5C2 and 0.42 mm s −1 for Fe3C. Recoil-free fractions for the two iron sites were also calculated at f300 0.785 and 0.726 for site 1 and 2 respectively.

Green and facile approach for enhancing the inherent magnetic properties of carbon nanotubes for water treatment applications

“…The parameters of the sextet are close to those reported for Fe 3 C (a catalyst used during CNT production [ 39 , 40 ]). As in previous studies we observe a significant reduction in the magnetic hyperfine field and an increase in the line width in comparison to pure Fe 3 C [ 41 , 42 ]. We interpret the deviation as being caused by extensive local disorder in the Fe 3 C particles of MCNT-Wako.…”

Topotactic transformation of metal–organic frameworks to iron-based catalysts for the direct hydrogenation of CO2 to olefins

“…7b and S7†), which may lead to different catalytic properties. 69,70 According to a literature survey (Table S8†), the contents of the specific Fe sites in Fe 5 C 2 (the Fe in sites II and III) and O/P are positively correlated, favouring the inhibition of carbon chain growth reactions and promoting olefin production, which further supports our conclusion that the content of the specific Fe sites in Fe 5 C 2 (sites II and III) has a modulating effect on O/P and olefin selectivity. On the basis of our findings, it can be concluded that: (1) doping of metal promoters into iron-based catalysts not only has an effect on the Fe 5 C 2 content, but also changes the content of the different Fe sites within Fe 5 C 2 (sites I, II and III); (2) the content of the specific Fe sites within Fe 5 C 2 (sites II and III) should be responsible for the O/P ratio and olefin selectivity.…”

Design and Catalytic Behaviour of Hosted in Activated Carbon Foam CoxZn1−xFe2O4 Ferrites

“…Indeed, the Mössbauer analyses of the used in the catalytic test materials demonstrated disappearance of the sextets attributable to the substituted magnetite (Table 4, Figures S5 and S6). Instead, a new sextet component with an isomer shift of about 0.2 mm/s and a low hyperfine field, typical of Fe3C carbide, were detected [75,76]. With the increase in the Co/Zn ratio in the samples, an additional low-intensive sextet with parameters attributable to an α-(Fe, Co) alloy appeared.…”