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Instruments / Technical Area	Publication Details	Published
B18-Core EXAFS I11-High Resolution Powder Diffraction	Fe K-edge X-ray Absorption Spectroscopy of corrosion phases of archaeological iron: results, limitations, and the need for complementary techniques Hayley Simon , Giannantonio Cibin , Ian Freestone , Eleanor Schofield Journal Of Physics: Condensed Matter DOI: 10.1088/1361-648X/ac08b6 Diamond Proposal Number(s): [16328] Open Access Show Abstract ▼ Abstract: Data analysis methods for iron X-ray Absorption Spectroscopy (XAS) can provide extensive information about the oxidation state and co-ordination of an Fe-species. However, the extent to which techniques developed using a single-phase iron sample may be applied to complex, mixed-phase samples formed under real-world conditions is not clear. This work uses a combination of pre-edge fitting and linear combination analysis (LCA) to characterise the near edge region of the X-ray absorption spectrum (XANES) for a set of archaeological iron corrosion samples from a collection of cast iron cannon shot excavated from the Mary Rose shipwreck and compares the data with phase compositions determined by Synchrotron X-ray Powder Diffraction (SXPD). Archaeological powder and cross-section samples were compared to a library of iron standards and diffraction data. The XANES are consistent with previous observations that generation of the chlorinated phase akaganeite, β-FeO(OH,Cl), occurs in those samples which have been removed form passive storage and subjected to active conservation. However, the results show that if any metallic species is present in the sample, the contribution from Fe(0) to the spectral region containing a pre-edge for oxidised iron – Fe(II) and Fe(III) – causes the analysis to be less effective and the conclusions unreliable. Consequently, while the pre-edge fitting methodology may be applied to a mixture of iron oxides or oxyhydroxides, the procedure is inappropriate for a mixed metal-oxide sample without the application of a complimentary technique, such as SXPD.	Jun 2021
B18-Core EXAFS	The formation of chemical degraders during the conservation of a wooden tudor shipwreck Esther Rani Aluri , Corentin Reynaud , Helen Bardas , Eleonora Piva , Giannantonio Cibin , J. Frederick W. Mosselmans , Alan Chadwick , Eleanor J. Schofield Chempluschem 62 DOI: 10.1002/cplu.202000160 Diamond Proposal Number(s): [10104] Open Access Show Abstract ▼ Abstract: Determining the nature, evolution, and impact of acid‐generating sulfur deposits in the Mary Rose wooden hull is crucial for protecting Henry VIII's famous warship for generations to come. Here, a comprehensive X‐ray absorption near‐edge spectroscopy (XANES) and X‐ray fluorescence (XRF) study sheds vital light on the evolution of complex sulfur‐based compounds lodged in Mary Rose timbers as a function of drying time. Combining insights from infrared spectroscopy correlates the presence of oxidized sulfur species with increased wood degradation via the loss of major wood components (holocellulose). Intriguingly, zinc is found to co‐exist with iron and sulfur in the most degraded wood regions, indicating its potential contributing role to wood degradation. This study provides crucial information on the degradation processes and resulting products within the wood, which can be used to develop remediation strategies to save the Mary Rose.	May 2020
B18-Core EXAFS I11-High Resolution Powder Diffraction I12-JEEP: Joint Engineering, Environmental and Processing	Influence of microstructure on the corrosion of archaeological iron observed using 3D synchrotron micro-tomography H. J. Simon , G. Cibin , C. Reinhard , Y. Liu , E. Schofield , I. C. Freestone Corrosion Science DOI: 10.1016/j.corsci.2019.108132 Diamond Proposal Number(s): [16863, 16328] Show Abstract ▼ Abstract: A combination of X-ray analytical techniques has been used to study the microstructure and corrosion of a 450-year-old cast-iron cannonball fragment from the Mary Rose shipwreck. Using a 3D approach, it has been shown that akaganeite, β-FeO(OH, Cl), starts to appear ˜1.5 mm below the outer surface of the object, occurring selectively around non-contiguous graphite flakes in the microstructure, with no corrosion in graphite-free regions. This spatial analysis has given a new look inside a 450-year-old system, to see how metallographic features interact with local chemical environments to give complex corrosion products, centuries in the making.	Aug 2019
	XAS studies of the effectiveness of iron chelating treatments of Mary Rose timbers A. Smith , A M. Jones , E. J. Schofield , J. F. W. Mosselmans , A. V. Chadwick , A. Berko , A. D. Smith 14th International conference on X-ray absorption fine structure (XAFS14) DOI: 10.1088/1742-6596/190/1/012147 Open Access Show Abstract ▼ Abstract: The oxidation of sulfur in marine archaeological timbers under museum storage conditions is a recently identified problem, particularly for major artefacts such as historic ships excavated from the seabed. Recent work on the Vasa has stressed the role of iron in catalysing the oxidative degradation of the wood cellulose and the polyethylene glycols used to restore mechanical integrity to the timbers. In developing new treatment protocols for the long term preservation of Henry VIII of England's flagship, the Mary Rose, we are investigating the potential of chelating agents to neutralise and remove the iron products from the ships timbers. We have explored the use of aqueous solutions of chelating agents of calcium phytate, ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA) and ammonium citrate to extract the iron compounds. All of these solutions exhibit some level of iron removal; however the key is to find the most effective concentration at pH of around 7 of the reagent solution, to minimise the treatment time and find the most cost-effective treatment for the whole of the Mary Rose hull. Fe K-edge XAFS data from samples of Mary Rose timbers, before and after treatment by the chelating agents mentioned has been collected. The data collected provide valuable insights into the effectiveness of the treatment solutions.	Oct 2009

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