E. Foy

Investigation at the nanometre scale on the corrosion mechanisms of archaeological ferrous artefacts by STXM

For the first time, corrosion products of a 450 year old archaeological iron nail were investigated at the nanometer level using STXM. NEXAFS acquisitions at the Fe L-edge were performed on a thin film taken of the metal–corrosion products including the interface. Comparison with Fe L-edge reference spectra gathered on maghemite (Fe2O3), magnetite (Fe3O4), siderite (FeCO3), chukanovite (Fe2(OH)2CO3) and metallic iron (Fe) showed the presence of an interfacial layer of about 100 nm at the metal–corrosion product interface consisting of maghemite and magnetite. Further from this interface, corrosion products are mainly constituted of Fe-carbonates, as well as smaller quantities of iron oxides, probably maghemite. These results support the hypothesis of the presence of a nanolayer controlling the corrosion processes at the metal–corrosion product interface, proposed during former studies at the macroscopic and microscopic levels. They also bring important new insights for the prediction of very long term corrosion of steels, especially into the fields of cultural heritage conservation and storage of nuclear wastes.

Combining μX-ray fluorescence, μXANES and μXRD to shed light on Zn2+ cations in cartilage and meniscus calcifications.

We aimed to examine the presence of Zn, a trace element, in osteoarthritis (OA) cartilage and meniscus from patients undergoing total knee joint replacement for primary OA. We mapped Ca(2+) and Zn(2+) at the mesoscopic scale by X-ray fluorescence microanalysis (μX-ray) to determine the spatial distribution of the 2 elements in cartilage, μX-ray absorption near edge structure spectroscopy to identify the Zn species, and μX-ray diffraction to determine the chemical nature of the calcification. Fourier transform infrared spectroscopy was used to determine the chemical composition of cartilage and meniscus. Ca(2+) showed a heterogeneous spatial distribution corresponding to the calcifications within cartilage (or meniscus) or at their surface. At least 2 Zn(2+) species were present: the first may correspond to Zn embedded in protein (different Zn metalloproteins are known to prevent calcification in biological tissues), and the second may be associated with a Zn trap in or at the surface of the calcification. Calcification present in OA cartilage may significantly modify the spatial distribution of Zn; part of the Zn may be trapped in the calcification and may alter the associated biological function of Zn metalloproteins.

Diversité chimique des calculs prostatiques : une investigation par MEB et spectroscopie infrarouge

OBJECTIVE Revisiting the chemical diversity of the crystalline phases of prostatic calculi by means of SEM and FT-IR analysis. METHODS A set of 32 prostatic calculi has been studied by FT-IR and SEM. RESULTS FT-IR analysis has determined the chemical composition of each prostatic calculus and the SEM observation has described the morphology of the calculi surfaces and layers. Infrared analysis revealed that 90.7% of the stones were mainly composed of calcium phosphates. However, several mineral phases previously not reported in prostatic calculi were observed, as brushite or octocalcium phosphate pentahydrate. CONCLUSION Prostatic calculi exhibited a diversity of crystalline composition and morphology. As previously reported for urinary calculi, relationships between composition and morphology of prostatic stones and étiopathogenic conditions could be of interest in clinical practice.

First examination of slag inclusions in medieval armours by confocal SR-µ-XRF and LA-ICP-MS

To elucidate the origin of armours supposed to be from Lombardy according to art-historians, the very small Slag Inclusions entrapped in the metallic matrix were analysed on the samples taken on armours. This paper presents the analytical protocol, based on the coupling of LA-ICP-MS and confocal SR-µ-XRF (confocal Micro-X-ray fluorescence under Synchrotron Radiation) developed to obtain trace element information from this kind of inclusion. Confocal SR-µ-XRF has been applied to inclusions of ancient iron artefacts for the first time. The reliability and reproducibility of the procedure developed for the trace elements quantifying have been checked by a comparison of the results obtained by LA-ICP-MS and by confocal SR-µ-XRF. Our first results allow us to draw some preliminary observations on the origin of the samples.

Silicon sheets by redox assisted chemical exfoliation.

In this paper, we report the direct chemical synthesis of silicon sheets in gram-scale quantities by chemical exfoliation of pre-processed calcium disilicide (CaSi2). We have used a combination of x-ray photoelectron spectroscopy, transmission electron microscopy and energy-dispersive x-ray spectroscopy to characterize the obtained silicon sheets. We found that the clean and crystalline silicon sheets show a two-dimensional hexagonal graphitic structure.

Influence of corrosion products nature on dechlorination treatment: case of wrought iron archaeological ingots stored 2 years in air before NaOH treatment

Abstract Three wrought iron ingots immersed during 2000 years at 12 m deep in Mediterranean Sea were stored after excavation for 2 years without specific protection in air. After that period, two of them were treated by immersion in a NaOH solution, while the third was used to describe the corrosion system resulting from the storage conditions. This characterisation was achieved by a combination of microanalytical techniques. It could be concluded that though ferrous hydroxychloride β-Fe2(OH)3Cl was the main Cl containing phase at the time of excavation, akaganeite [β-FeO1–x(OH)1+xClx] was the only one present in the rust layers after storage. In order to determine the influence of corrosion products nature on dechlorination treatment, the evolution of a corrosion system composed of both Cl containing phases β-FeOOH and β-Fe2(OH)3Cl has been followed during in situ NaOH experimental treatment. Specific behaviours of each phase to the dechlorination treatment have been revealed.

In situ monitoring of corrosion processes by coupled micro-XRF/micro-XRD mapping to understand the degradation mechanisms of reinforcing bars in hydraulic binders from historic monuments

Historic monuments have been partly built since antiquity with iron or steel reinforcements sealed in mortars or hydraulic binders. But the presence of chloride in the environment can weaken the structures due to the corrosion of these metallic parts, leading to the cracking of the binder. In this context, in order to better understand the first steps of these corrosion mechanisms a chemical cell was designed to operate in situ analyses of the phases precipitated when a chlorinated solution is introduced in the vicinity of the bar. The chemical and structural characterization (micro-XRF and micro-XRD respectively) was performed under synchrotron radiation at the SOLEIL-DiffAbs beamline. Moreover, complementary SEM-EDS analyses were carried out before and after the in situ cell experiment in order to determine the final localisation of the corrosion products inside the crack network. The results show that iron can spread up to 1 mm away from the metallic bar inside the pores of the binder after 44 h of corrosion. Moreover, in accordance with laboratory experiments conducted in solution in the presence of Fe2+ and Cl− ions the reaction pathways conduct to the successive formation of an intermediate Fe(II)–Fe(III) chlorinated green rust which transforms into ferric oxyhydroxides such as akaganeite or goethite depending on the local concentration of iron.

MAGNETIC PROPERTIES OF ULTRA-THIN MN FILMS GROWN ON (001) BCC FE

The structural and magnetic properties of ultra-thin Mn films epitaxially grown on (0 0 1) Fe are investigated by X-ray absorption and magnetic circular dichroism. On the one hand, Mn is observed to grow in a BCT structure up to 2 atomic planes. A ferromagnetic order within the Mn layer and a ferromagnetic Mn/Fe coupling are observed. Above 2 monolayers, the Mn structure changes and the ferromagnetic order disappears. However, this structural transition is due to the increase of the Mn film dimension from 2D to 3D, but not due to the structural transition. On the other hand, the magnetic properties below 2 monolayers are observed to drastically change when the Mn films are oxidized. The Mn/Fe coupling observed to be ferromagnetic in unoxidized Mn films becomes antiferromagnetic when the Mn film is oxidized.

Presence and role of trace elements in urinary calculi

AIM To assess the possible nature and role of trace elements in the pathogenesis of urinary stones. MATERIAL AND METHOD A series of 76 calculi from the East-Algerian region has been investigated through Fourier transform infrared spectroscopy for chemical analysis and X-ray fluorescence for detecting trace elements. RESULTS Among the detected trace elements, Zn, Sr, Pb, Cu, Rb and Se, only the first three had significant values. Overall, the calcium components, namely calcium oxalate and calcium phosphate, were the most loaded by these elements contrary to organic components such as uric acid and cystine, which had low contents. CONCLUSION The correlation of contents of Zn and Sr with the stone components (carbapatite, weddellite and whewellite) suggests an adsorption of these trace elements in the case of calcium stones rather than a catalytic process. LEVEL OF EVIDENCE 3.

Evidence of bcc Mn epitaxial growth in Mn/MxV1-x(001) (M = Fe, Nb) superlattices

Abstract:This study is dedicated to the growth of bcc Mn by molecular beam epitaxy, in order to look at the magnetic properties of bcc Mn near room temperature. For this purpose, Mn is deposited on bcc MxV1-x(001) alloy lattices (M = Fe or Nb) for which the lattice spacing is tunable by varying the concentration x. We first show that the parameter of the MxV1-x alloys buffer layers can be adjusted from 2.95 Å to 3.3 Å depending on x and M. Three different structures in Mn films grown on these buffer layers are observed depending on the in-plane spacing of the initial MxV1-x lattice. Thick Mn films are always found to grow epitaxially in the Mnα structure. For moderate thicknesses larger than 4 atomic planes, Mn grows in an unidentified structure. Finally, up to four deposited atomic planes, Mn is found to grow in a tetragonal structure close to a bcc one on Fe(001), FexV1-x(001) and NbxV1-x(001) for