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Schaaf, Peter; Lieb, Klaus; Carpene, E.; Han, Meng; Landry, Felix

doi:10.1023/a:1017688914737

Cited by 9 publications

(9 citation statements)

References 54 publications

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“…However, the literature of Mo ¨ssbauer spectra for various forms of iron nitride does not report any spectra with similar parameters. [43][44][45][46][47][48] The Mo ¨ssbauer spectra contained the same four species regardless of treatment time, although the relative intensities of the species changed. It should be pointed out that the initial guess used for these samples was based on the initial fit for the sample treated for 2 h. The spectra in Figure 5a clearly shows the change in the relative intensities of the sextet yielding carbide species for treatments of 20 min, 2 h, and 12 h. From the Figure, it can be seen that the carbide contribution grows with treatment time while the metallic Fe phase decreases.…”

Section: Resultsmentioning

confidence: 99%

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Characterization of the Iron Phase in CN_x-Based Oxygen Reduction Reaction Catalysts

et al. 2007

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Catalysts for the oxygen reduction reaction were prepared from the pyrolysis of acetonitrile at 900 °C over iron particles on various supports. The iron phases present in the active materials were characterized by XRD, TEM, and Mössbauer spectroscopy. Typically, the iron particles were encased in carbon after pyrolysis, explaining how they could survive subsequent acid washes. The Fe phases present included metallic gamma iron, cementite, and two oxidized phases. Although the relative abundance of the phases varied with different supports, with treatment time, and after washing, there was no apparent correlation between the presence or abundance of a phase and activity. The phases present are consistent with Fe particles used to catalyze the formation of carbon fibers by catalytic chemical vapor deposition. After being washed with acid, there was no evidence for the presence of nitrogen-stabilized Fe sites on the carbon surface. These results support the hypothesis that Fe catalyzes the formation of ORR-active carbon nanostructures during pyrolysis at 900 °C in a carbon and nitrogen atmosphere and is not part of an active site itself.

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Section: Resultsmentioning

confidence: 99%

“…Because there is evidence of a carbide species and both nitrogen and carbon were present in the fibers, one may also expect a nitride species to be formed upon treatment with acetonitrile. However, the literature of Mössbauer spectra for various forms of iron nitride does not report any spectra with similar parameters. − …”

Section: Resultsmentioning

confidence: 99%

Characterization of the Iron Phase in CN_x-Based Oxygen Reduction Reaction Catalysts

et al. 2007

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“…[1,2] Nitride coatings have also been shown to improve wear resistance and enhance hardness of Fe and steel. [3] Several deposition techniques have been used for nitriding including vapor deposition, [4] molecular beam epitaxy, [5] laser nitriding, [6] and reactive sputtering [1,2,[7][8][9] by showing a large number of phases of the Fe-N phase diagram. Even though there are many studies dealing with such nitriding processes, their ruling phenomena are still quite unclear, especially for stainless steels.…”

Section: Introductionmentioning

confidence: 99%

Nitrided Amorphous Stainless Steel Coatings Deposited by Reactive Magnetron Sputtering from an Austenitic Stainless Steel Target

Cusenza¹,

Jürgens²,

Uhrmacher³

et al. 2009

Adv Eng Mater

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Stainless steel films were reactively magnetron sputtered in argon/nitrogen gas flow onto oxidized silicon wafers using austenitic AISI 316 stainless‐steel targets. The deposited films of about 300 nm thickness were characterized by conversion electron Mö‐i;ssbauer spectroscopy, magneto‐optical Kerr‐effect, X‐ray diffraction, Rutherford backscattering spectrometry, and resonant nuclear reaction analysis. These complementary methods were used for a detailed examination of the nitriding effects for the sputtered stainless‐steel films. The formation of an amorphous and soft ferromagnetic phase in a wide range of the processing parameters was found. Further, the influence of postvacuum‐annealing was examined by perturbed angular correlation to achieve a comprehensive understanding of the nitriding process and phase formation. The amorphous phase is not very stable and crystallization can be observed at 973 K.

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“…Nevertheless, the ordering of nitrogen interstitials as well as the proper fitting of the hyperfine parameters are still in discussion. In spite of the several attempts performed to obtain the interaction between atoms from the Mössbauer data [3][4][5][6][7][8][9][10][11] and the numerous articles on the distribution of solute atoms in the interstitial sites [12,13], up to now, there has been no full understanding on the way the interstitial atoms are distributed.…”

Section: Introductionmentioning

confidence: 99%

Interstitial ordering of nitrogen and carbon in laser nitrided and laser carburized austenitic stainless steel

Binczycka

Kahle

Cusenza

et al. 2006

J. Phys.: Condens. Matter

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The distribution of carbon and nitrogen atoms on the octahedral interstitial sites of the face-centred-cubic austenite phase in Fe–C and Fe–N alloys, especially in austenitic stainless steel, is still causing controversy. In this work, results of Mössbauer experiments are presented in order to advance the understanding of this interstitial occupation. Therefore, laser carburized and laser nitrided austenitic stainless steel was investigated by means of x-ray diffraction and Mössbauer spectroscopy. Three subspectra in terms of different iron sites were resolved in the Mössbauer spectra for these iron–carbon and iron–nitrogen austenites. The isomer shifts, the quadrupole splittings and in particular the subspectra fractions depend on the type of the introduced atom and undergo changes when increasing the carbon or nitrogen content. This is discussed in connection with the existing ordering models for interstitial atoms. No clear evidence could be found for a perfect random occupation, nor for a perfect ordered occupation of the interstitials. Nevertheless, there seems to a tendency for a weak attractive interaction for nitrogen interstitials, and for a stronger repulsive force for the carbon interstitials in laser nitrided/carburized austenitic stainless steel.

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Untitled

Cited by 9 publications

References 54 publications

Characterization of the Iron Phase in CN_x-Based Oxygen Reduction Reaction Catalysts

Characterization of the Iron Phase in CN_x-Based Oxygen Reduction Reaction Catalysts

Nitrided Amorphous Stainless Steel Coatings Deposited by Reactive Magnetron Sputtering from an Austenitic Stainless Steel Target

Interstitial ordering of nitrogen and carbon in laser nitrided and laser carburized austenitic stainless steel

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Untitled

Cited by 9 publications

References 54 publications

Characterization of the Iron Phase in CNx-Based Oxygen Reduction Reaction Catalysts

Characterization of the Iron Phase in CNx-Based Oxygen Reduction Reaction Catalysts

Nitrided Amorphous Stainless Steel Coatings Deposited by Reactive Magnetron Sputtering from an Austenitic Stainless Steel Target

Interstitial ordering of nitrogen and carbon in laser nitrided and laser carburized austenitic stainless steel

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Characterization of the Iron Phase in CN_x-Based Oxygen Reduction Reaction Catalysts

Characterization of the Iron Phase in CN_x-Based Oxygen Reduction Reaction Catalysts