Mössbauer Spectroscopy

Gager, H. M.; Hobson, M.C.

doi:10.1080/01614947508079983

Cited by 34 publications

(8 citation statements)

References 80 publications

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“…It includes two components: a paramagnetic doublet assigned to highly dispersed Fe 3+ and a magnetic sextet related to iron(III) oxide particles with a particle size larger than that responsible for the doublet. The hyperfine field corresponding to the sextet (50.4 T) is lower than that of bulk α‐Fe 2 O 3 (51.5 T) 62,63. This fact points to the presence of small α‐Fe 2 O 3 particles with a diameter of between 7 and 12 nm 64.…”

Section: Resultsmentioning

confidence: 91%

Surface and Structural Features of Co‐Fe Oxide Nanoparticles Deposited on a Silica Substrate

et al. 2006

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Keywords: Cobalt / Iron / Oxides / Metal-metal interactions / Materials science Mono-and dimetallic cobalt-and iron oxide nanoparticles deposited on the surface of a silica substrate have been prepared by an impregnation technique. Both the bulk and surface structures of these particles have been characterised by different physical and chemical techniques. The results provided by X-ray diffraction, Mössbauer and X-ray photoelectron spectroscopy show the formation of separate Co 3 O 4 and Fe 2 O 3 nanoparticles in oxide samples, but in no case were cobalt-iron mixed oxides detected. Quantitative data also showed that the dispersion degree of cobalt-and iron oxides is rather low. It was also observed that pretreatment of the supported metal oxide nanoparticles under a hydrogen atmosphere does not promote the formation of a metal-support

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Section: Resultsmentioning

confidence: 91%

Surface and Structural Features of Co‐Fe Oxide Nanoparticles Deposited on a Silica Substrate

et al. 2006

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“…Mössbauer Spectroscopy . Mössbauer spectroscopy is particularly useful for the study of Fe catalysts. − Figure shows room-temperature Mössbauer spectra obtained for the 5 wt % Fe/ZrO 2 catalysts calcined at various temperatures. The spectra are composed of a doublet component and a magnetically split sextet component.…”

Section: Resultsmentioning

confidence: 99%

“…The Mo ¨ssbauer results indicate that analogous species predominate after drying at 383 K. The Mo ¨ssbauer parameters in Tables 1 and 2 are in good agreement with the formation of FeOOH‚ nH 2 O species. 38,45 Taking into account that sextet (A) shows superparamagnetism at RT, it is concluded that sextet (A) is assigned to partially hydrated FeOOH fine particles.…”

Section: Discussionmentioning

confidence: 99%

“…Doublet components result from paramagnetic and/or superparamagnetic Fe species, while sextet components from Fe species in magnetically ordered states as anti-ferromagnet or ferromagnet. [37][38][39][40][41][42] In the present study, the former components include isolated Fe 3+ species and/or highly dispersed Fe 3+ oxide or oxyhydroxide species. The area fractions of the doublet and sextet components are determined from the spectra in Figure 3 and summarized in Table 1.…”

Section: X-ray Diffraction (Xrd) Shown In Figurementioning

confidence: 99%

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Metal Oxide−Support Interactions in Fe/ZrO₂ Catalysts

et al. 2000

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To reveal the metal oxide−support interactions in ZrO2-supported Fe oxide catalysts as a function of calcination temperature, 5 wt % Fe/ZrO2 was characterized by means of 57Fe Mössbauer spectroscopy, IR, XRD, and thermogravimetric analysis. The catalytic activity of Fe/ZrO2 was examined at 523 K for NO−CO reaction. It is shown that when Fe/ZrO2 is calcined below 573 K, small particles of hydrated Fe3+ oxyhydroxides (superparamagnetic at 297 K) are formed together with Fe3+ paramagnetic species ion-exchanged with the surface OH groups of ZrO2. In addition to the Fe3+ ion-exchanged species, Fe3+ oxide clusters and crystalline α-Fe2O3 particles are formed by successive dehydration of the oxyhydroxides on calcination at 973 K. When Fe/ZrO2 is calcined at 1073 or 1173 K, the Mössbauer spectroscopic results suggest the formation of Fe3+ cations trapped in surface vacant sites of ZrO2 at the expense of the Fe3+ oxide clusters. On the calcination at a higher temperature, crystalline α-Fe2O3 predominates with a small portion of the Fe3+ cations being in surface vacant sites. With 2 wt % Fe/ZrO2 prepared by a coprecipitation method and calcined at 1173−1373 K, Fe3+ cations dissolved in a ZrO2 lattice are formed in addition to a small amount of magnetically split component.

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“…The spectra of the fresh catalysts all consist of a doublet with IS = 0.63 5 0.03 mm/s and QS = 0.84 + 0.06 mm/s, characteristic of Fe3+ ions in highly dispersed iron(II1) oxides or oxyhydroxides (16,32). The spectra of the reduced catalysts have been discussed in the previous section.…”

Section: Reduced Catalystsmentioning

confidence: 94%

M�ssbauer and X-ray photoelectron spectroscopic evidence for the structure of supported bimetallic catalysts: FeRu, FeRh, FePd, Felr, and FePt on SiO2

Niemantsverdriet¹,

KAAM²,

Flipse

et al. 1985

Journal of Catalysis

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Mössbauer Spectroscopy

Cited by 34 publications

References 80 publications

Surface and Structural Features of Co‐Fe Oxide Nanoparticles Deposited on a Silica Substrate

Surface and Structural Features of Co‐Fe Oxide Nanoparticles Deposited on a Silica Substrate

Metal Oxide−Support Interactions in Fe/ZrO₂ Catalysts

M�ssbauer and X-ray photoelectron spectroscopic evidence for the structure of supported bimetallic catalysts: FeRu, FeRh, FePd, Felr, and FePt on SiO2

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Mössbauer Spectroscopy

Cited by 34 publications

References 80 publications

Surface and Structural Features of Co‐Fe Oxide Nanoparticles Deposited on a Silica Substrate

Surface and Structural Features of Co‐Fe Oxide Nanoparticles Deposited on a Silica Substrate

Metal Oxide−Support Interactions in Fe/ZrO2 Catalysts

M�ssbauer and X-ray photoelectron spectroscopic evidence for the structure of supported bimetallic catalysts: FeRu, FeRh, FePd, Felr, and FePt on SiO2

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Metal Oxide−Support Interactions in Fe/ZrO₂ Catalysts