Iron corrosion in archaeological context: Structural refinement of the ferrous hydroxychloride β-Fe2(OH)3Cl

Ferrous hydroxysalts are found in corrosion layers of archaeological ferrous objects extracted from oxygen-poor environments. The structure of synthetic and natural β-Fe2(OH)3Cl was investigated by X-ray absorption spectroscopy and X-ray diffraction. The local environments of Cl− and Fe2+ were precisely determined showing the same structure around Cl− and Fe2+ atoms whatever the natural or synthesized phase. The crystalline structure was refined confirming the rhombohedral unit cell and R-3m space group. However slight differences observed for the structural parameters and on XRD patterns suggested different crystallite size, strain effects and the influence of the crystallization process.

[1]  Christian Degrigny,et al.  Use of electrochemical techniques for the conservation of metal artefacts: a review , 2010 .

[2]  I. Guillot,et al.  XAS and XRD in situ characterisation of reduction and reoxidation processes of iron corrosion products involved in atmospheric corrosion , 2014 .

[3]  P. Dillmann,et al.  A study of the Roman iron bars of Saintes-Maries-de-la-Mer (Bouches-du-Rhône, France). A proposal for a comprehensive metallographic approach , 2011 .

[4]  G. Patterson,et al.  The role of chlorine in serpentinization , 1977 .

[5]  T. Misawa,et al.  The mechanism of formation of iron oxide and oxyhydroxides in aqueous solutions at room temperature , 1974 .

[6]  F. Marsal,et al.  Influence of an aerated/anoxic transient phase on the long-term corrosion of iron , 2014 .

[7]  Neil A. North,et al.  WASHING METHODS FOR CHLORIDE REMOVAL FROM MARINE IRON ARTIFACTS , 1978 .

[8]  M. Fleet.  The crystal structure of paratacamite, Cu2(OH)3Cl , 1975 .

[9]  P. Lagarde,et al.  Structural evidence for the desalination of akaganeite in the preservation of iron archaeological objects, using synchrotron X-ray powder diffraction and absorption spectroscopy , 2009 .

[10]  E. Foy,et al.  Mechanisms of long-term anaerobic corrosion of iron archaeological artefacts in seawater , 2009 .

[11]  M. Nemer,et al.  Solubility of Fe2(OH)3Cl (pure-iron end-member of hibbingite) in NaCl and Na2SO4 brines , 2011 .

[12]  M Newville,et al.  IFEFFIT: interactive XAFS analysis and FEFF fitting. , 2001, Journal of synchrotron radiation.

[13]  J. Mizuki,et al.  Cl K-Edge XANES Spectra of Atmospheric Rust on Fe, Fe-Cr and Fe-Ni Alloys Exposed to Saline Environment , 2004 .

[14]  Michel Daudon,et al.  Combination of X-ray synchrotron radiation techniques to gather information for clinicians , 2016 .

[15]  G. Springer.  Chlorine-bearing and other uncommon minerals in the Strathcona deep copper zone, Sudbury District, Ontario , 1989 .

[16]  F. Nicot,et al.  Mechanisms of the dechlorination of iron archaeological artefacts extracted from seawater , 2011 .

[17]  P. M. D. Wolff.  The crystal structure of Co2(OH)3Cl , 1953 .

[18]  G. K. Williamson,et al.  X-ray line broadening from filed aluminium and wolfram , 1953 .

[19]  P. Refait,et al.  The mechanisms of oxidation of ferrous hydroxychloride β-Fe2(OH)3Cl in aqueous solution: The formation of akaganeite vs goethite , 1997 .

[20]  S. Turgoose,et al.  POST-EXCAVATION CHANGES IN IRON ANTIQUITIES , 1982 .

[21]  M Newville,et al.  ATHENA, ARTEMIS, HEPHAESTUS: data analysis for X-ray absorption spectroscopy using IFEFFIT. , 2005, Journal of synchrotron radiation.

[22]  P. Dillmann,et al.  Buried iron archaeological artefacts: Corrosion mechanisms related to the presence of Cl-containing phases , 2007 .

[23]  Philippe Dillmann,et al.  Deterioration of iron archaeological artefacts: micro-Raman investigation on Cl-containing corrosion products , 2007 .

[24]  J. Parise,et al.  The structure of atacamite and its relationship to spinel , 1986 .

[25]  Kurt Nielsen,et al.  On the akaganéite crystal structure, phase transformations and possible role in post-excavational corrosion of iron artifacts , 2003 .

[26]  Takanobu Suzuki,et al.  K x‐ray absorption spectra of chlorine in 3d transition‐metal complexes , 1981 .

[27]  V. Argyropoulos,et al.  The corrosion of excavated archaeological iron with details on weeping and akaganéite , 1999 .

[28]  R. Cawthorn.,et al.  SUSPECTED PRESENCE OF HIBBINGITE IN OLIVINE PYROXENITE ADJACENT TO THE UG2 CHROMITITE, BUSHVELD COMPLEX, SOUTH AFRICA , 2009 .

[29]  H. Keppler,et al.  Hibbingite, gamma -Fe 2 (OH) 3 Cl, a new mineral from the Duluth Complex, Minnesota, with implications for the oxidation of Fe-bearing compounds and the transport of metals , 1994 .

[30]  F. Nicot,et al.  Influence of crucial parameters on the dechlorination treatments of ferrous objects from seawater , 2012 .

[31]  Mourad Idir,et al.  LUCIA, a microfocus soft XAS beamline , 2006 .

[32]  J. Post,et al.  Crystal structure refinement of akaganéite , 1991 .

[33]  H. Oswald,et al.  Über die Hydroxidhalogenide Me2(OH)3Cl, ‐Br, ‐J zweiwertiger Metalle (Me = Mg, Ni, Co, Cu, Fe, Mn) , 1964 .

[34]  J. Rucklidge,et al.  The occurrence of chlorine in serpentine minerals , 1981 .

[35]  E. Dahlberg,et al.  A CHLORINE-BEARING PHASE IN DRILL CORE OF SERPENTINIZED TROCTOLITIC ROCKS OF THE DULUTH COMPLEX, MINNESOTA , 1991 .

[36]  P. Refait,et al.  Formation, fast oxidation and thermodynamic data of Fe(II) hydroxychlorides , 2008 .