Raman Studies of Corrosion Layers Formed on Archaeological Irons in Various Media

Bellot‐Gurlet, Ludovic; Neff, Delphine; Réguer, Solenn; Monnier, Judith; Saheb, Mandana; Dillmann, Philippe

doi:10.4028/www.scientific.net/jnanor.8.147

Cited by 119 publications

(101 citation statements)

References 54 publications

(71 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Hematite was found also in other works as the result of laser heating. 54,61 Hematite has an intense spectrum characterized by the strong resonant band at 1310 cm −1 under green excitation. 61 Further Raman experiments have been conducted with dry samples.…”

Section: Resultsmentioning

confidence: 99%

Raman Spectroscopy of Mackinawite FeS in Anodic Iron Sulfide Corrosion Products

Genchev

Erbe

2016

J. Electrochem. Soc.

112

View full text Add to dashboard Cite

Raman spectroscopy in a confocal microscope was used to study electrochemically synthesized corrosion products from sour gas experiments. When exposed to oxygen-containing atmosphere, the initial mackinawite FeS corrosion product transformed under laser irradiation to hematite, Fe 2 O 3 . Measurements with a thin water layer on top of the corrosion products prevented the transformation, as drying was prevented. In situ Raman measurements of mackinawite formation avoided the problem of transformation completely. In situ and operando, the initially formed mackinawite showed two Raman peaks in the wavenumber range >180 cm −1 centered around 200-215 cm −1 and 285-300 cm −1 . On an empirical basis, these modes were assigned to a B 1g mode of the iron sublattice and an A 1g mode of the sulfur sublattice, respectively. A comparison with a literature assignment for aged mackinawite suggests that the aging observed involves significant changes in the sulfur sublattice. Corrosion of iron in H 2 S containing solutions is a general problem in crude oil and natural gas production, and is generally referred to as sour corrosion. Aqueous H 2 S solutions promote corrosion of steels, [1][2][3] but the exact nature and mechanisms of corrosion strongly depend on the reaction conditions. 4-7 While the process has been widely investigated for pure iron, [8][9][10][11][12] and carbon steels, [13][14][15][16][17] there is still a lack of understanding of the reaction path and electronic properties of the corrosion products. 18,19The chemistry of the corrosion products formed during H 2 Striggered corrosion is rather complex, as there are many different solids consisting only of iron and sulfur. 20 However, mackinawite has been found to be the initial, 8,21 and probably most important corrosion product, of iron in aqueous sulfide solutions as it was observed in reactions carried out over a wide range of pH and temperature. 11,19,[22][23][24] It possesses a tetragonal, layered crystal structure, [25][26][27] and can be synthesized by precipitation from solutions containing Fe 2+ and S 2− solutions, 28,29 or by reaction of sulfide solution with metallic iron. 19,21,26,30 In the field of microbially induced corrosion, sulfatereducing bacteria are known to transform sulfate compounds into iron sulfides, e.g. mackinawite. [31][32][33][34][35][36] Raman spectroscopy has become an important tool for identification of corrosion products. [37][38][39][40][41][42][43][44][45] Some major problems may still occur due to laser heating, fluorescence, or low sensitivity as a consequence of the small cross-sections of Raman scattering. However, the fact that glass and water are both very weak Raman scatterers makes this technique suitable for in situ measurements in aqueous environments. 46-48The presence of water has an additional positive effect on the process as it decreases the heating from the laser. The use of (in situ and operando) Raman spectroscopy for study corrosion process studies of iron in sulfide rich environments has been already repor...

show abstract

Section: Resultsmentioning

confidence: 99%

Raman Spectroscopy of Mackinawite FeS in Anodic Iron Sulfide Corrosion Products

Genchev

Erbe

2016

J. Electrochem. Soc.

112

View full text Add to dashboard Cite

show abstract

“…The resulting values are in good agreement with those reported in literature. [47,[73][74][75][76] Previous assignments of a Raman mode to every band were unclear and/or conflicting. We decided to assign the Raman modes in accord to the results of Shebanova and Lazor, [47] which performed extensive polarized Raman measurements to fill the existing gap.…”

Section: Ferrite Spinelsmentioning

confidence: 99%

Raman fingerprint of chromate, aluminate and ferrite spinels

D’Ippolito

Andreozzi

Bersani

et al. 2015

J Raman Spectroscopy

328

221

View full text Add to dashboard Cite

Synthetic and natural spinel single crystals having compositions closely approaching spinel end-members ZnCr2O4, MgCr2O4, FeCr2O4, ZnAl2O4, MgAl2O4, CoAl2O4, FeAl2O4, MnAl2O4, MgFe2O4, and FeFe2O4 were investigated by Raman spectroscopy in the 100-900cm-1 range using both the red 632.8nm line of a He-Ne laser and the blue 473.1nm line of a solid-state Nd:YAG laser. Each end-member exhibits a Raman fingerprint with at least one peculiar peak in terms of Raman shift and relative intensity. Chromates and ferrites exhibit the most intense A1g mode at around 680cm-1, at lower wavenumbers than in the aluminates, in agreement with the heavier atomic mass of Cr and Fe with respect to Al. For aluminate spinels, the most intense and diagnostic peaks in the spectrum are as follows: F2g(1) at 202cm-1 for MnAl2O4, Eg at 408cm-1 for MgAl2O4, F2g(2) at 516cm-1 for CoAl2O4, F2g(3) at 661cm-1 for ZnAl2O4, and A1g at 748cm-1 for FeAl2O4. Noteworthy, analyzing the A1g, F2g(3), and, in particular, the Eg peak positions, it is possible to establish which subgroup a spinel belongs to; moreover, a careful inspection of both position and relative intensity of the same peaks allows the determination of the end-member type

show abstract

“…1 c) after oxidation evidences formation of a crystallized surface oxide containing thermodynamically stable ␣-Fe 2 O 3 (hematite) together with a small amount of Fe 3 O 4 (magnetite) [31][32][33][34][35]. The characteristic peak of Cr 2 O 3 centered at 549 cm −1 (A 1g mode of Cr 2 O 3 ) [36] is not observed, indicating non-detectable presence of the Cr 2 O 3 phase in the surface oxide.…”

Section: Composition and Phases Of Thermal (Fecr)-binary Oxidementioning

confidence: 78%