Germana Barone

Combined non-destructive XRF and SR-XAS study of archaeological artefacts

AbstractWe report on a non-destructive study of Sicilian ceramic fragments of cultural heritage interest, classified as “proto-majolica” pottery and dating back to the twelfth to thirteen centuries AD. The analytical approach used is based on the employment of two totally non-invasive spectroscopic techniques: X-ray fluorescence (XRF), using a portable energy-dispersive XRF analyser, and X-ray absorption spectroscopy, using synchrotron radiation as a probe (SR-XAS). XRF measurements allowed us to collect elemental and spatially resolved information on major and minor constituents of the decorated coating of archaeological pottery fragments, so providing preliminary results on the main components characterizing the surface. In particular, we assigned to Fe and Mn the role of key elements of the colouring agent. With the aim of obtaining more detailed information, we performed SR-XAS measurements at the Fe and Mn K-edges at the Italian BM08 beamline at the European Synchrotron Radiation Facility (Grenoble, France). The experimental data were analysed by applying principal component analysis and least-squares fitting to the near-edge part of the spectra (X-ray absorption near-edge structure) to determine the samples’ speciation. From the overall results, umber, a class of brownish pigments characterized by a mixture of hydrated iron and manganese oxides, has been ascribed as a pigmenting agent. FigureFe K-edge XANES spectra of selected proto-majolica samples and reference compounds (FeO, Fe3O4, Fe2O3, Fe+SiO2). D pigmented, L not pigmented.

The Use of FTIR and Micro-FTIR Spectroscopy: An Example of Application to Cultural Heritage

Micro-FTIR and FTIR spectroscopy is useful for the study of degradation forms of cultural heritage. In particular it permits to identify the degradation phases and to establish the structural relationship between them and the substratum. In this paper, we report the results obtained on marble from a Roman sarcophagus, located in the medieval cloister of St. Cosimato Convent (Rome), and on oolitic limestone from the facade of St. Giuseppe Church in Syracuse (Sicily). The main components found in the samples of both monuments are: gypsum, calcium oxalate, and organic matter due to probably conservation treatments. In particular, the qualitative distribution maps of degradation products, obtained by means of micro-FTIR operating in ATR mode, revealed that the degradation process is present deep inside the stones also if it is not visible macroscopically. This process represents the main cause of crumbling of the substrate. The results of this research highlight the benefits of the 𝜇-FTIR analysis providing useful insights on the polishing and consolidation processes of stone materials.

Nanocrystalline TiO2 coatings by sol–gel: photocatalytic activity on Pietra di Noto biocalcarenite

Self-cleaning photocatalytic coatings based on TiO2 nanoparticles obtained by sol–gel techniques at two different pH values (1.3–10.6) have been investigated on carbonatic stone. The selected material is the yellowish lithofacies of Palazzolo Formation calcarenite, commonly named Pietra di Noto, widely used in the Baroque monuments of the Noto Valley (Sicily, Italy). SEM–EDS, XRD and Raman investigations were carried out to characterize the TiO2 nanoparticles (mainly nanocrystalline anatase) obtained by the acid and basic nanosols and the corresponding coatings on pietra di Noto. To evaluate the effects of the treatments at two different pH values, changes in the stone color appearance, water absorption by capillarity and the behavior for salt crystallization were measured. The photocatalytic activity of the coatings was evaluated under UV irradiation, by monitoring methyl orange and methylene blue dye degradation as a function of time. The results highlight the compatibility of both treatments with respect to the properties of the calcarenite stone, showing no chromatic changes, no alteration of physical properties, an improvement in the resistance to salts crystallization and the good photocatalytic activity on both dyes. The experimental data suggest that the basic coating has to be preferred for carbonatic stones for its harmlessness and better performances in terms of self-cleaning action and protection against water and salts.Graphical AbstractSelf-cleaning photocatalytic coatings based on TiO2, obtained by sol–gel at two different pH values, are applied on Pietra di Noto carbonatic stone. TiO2 nanoparticles and coatings are characterized by SEM, XRD and Raman. The photocatalytic activity of the coatings is evaluated under UV irradiation, by monitoring methyl orange and methylene blue dye degradation as a function of time. The basic coating is suitable for carbonatic stones for its harmlessness and better performances in terms of self-cleaning action and protection against water and salts.

A multidisciplinary investigation on archaeological excavation in Messina (Sicily). Part I: a comparison of pottery findings in "the Strait of Messina area"

Abstract About 47 pottery samples, representative of different ceramic classes, have been investigated using X-ray diffraction, Fourier transformed infrared absorption, optical microscopy, scanning electron microscopy and chemical analysis. The obtained results have also been compared with analysis performed on clays and gravels in the surrounding area of Messina (Gravitelli, Annunziata) where the pottery was excavated. The experimental data allowed the authors to establish the quantity and quality of the characteristic components of each ceramic class, confirming that many of them were made at the local factory in Messina.

Small angle neutron scattering as fingerprinting of ancient potteries from Sicily "Southern Italy…

Small angle neutron scattering measurements have been carried out in order to investigate, in microdestructive way, the mesoscopic structure of a variety of potteries of relevance to cultural heritage coming from different Sicilian (Southern Italy) archeological sites belonging to the “Strait of Messina” area and dated back to 7th–3rd century B.C. Data have been compared with the mesoscopic parameters extracted for two series of clayey sediments typical of the Strait of Messina area and fired under controlled conditions. The observed agreement between the features of reference and archeological samples allowed us to estimate the maximum firing temperature of the latter. Information on the pore sizes was obtained by the use of the concept of fractal surface, and compared with porosimetry results.

A multi-technique approach for the determination of the porous structure of building stone

The complete knowledge of the porous structure of rocks is necessarily requested for the prediction of the damages induced by salt crystallization. Nevertheless, the geometric description of the porous structure is usually very difficult because of the variability of the size distribution of voids, ranging from nanometers to millimeters, which generally is not accessible by a single methodology. For this reason, a multi-technique approach was used here: the investigation at sub-micrometric dimensional scale (> 0.004 μm) was carried out by Hg intrusion porosimetry (MIP), whereas the study at the nanoscale required Small Angle Neutron Scattering (SANS) analysis. All the results were interpreted in the framework of a fractal model. The analyses were performed on limestones of different geological formations, cropping out in south-eastern Sicily and largely used as building stones in Baroque monuments of the Noto Valley (belonging to the UNESCO Heritage List).

Characterization of pottery fragments by nondestructive neutron diffraction

The aim of the present work is the characterization of pottery fragments coming from the town of Caltagirone (Sicily, Italy). The samples belong to very different historical periods, from 18th century B.C. to 16th century A.D., and have finely decorated surfaces. Time-of-flight neutron-diffraction measurements were performed in order to obtain a quantitative identification of the mineralogical composition of the samples. A good determination of the relative weight fractions of the phases was obtained using the Rietveld analysis method. The application of neutron-diffraction technique allowed us to carry out a detailed analysis in a nondestructive way, so intact large fragments were investigated without damaging the precious decoration on the surface.

A multidisciplinary investigation on archaeological excavation in Messina (Sicily). Part II. A study of the transport amphorae

Abstract In this paper, the results of the analyses performed on transport amphorae found in Messina are reported. In particular, the so-called “Corinthian B”, “ionio-massaliote” and “pseudo-chiote” amphorae have been studied. From a microscopic point of view, their fabric is not homogeneous, and a relevant part of the analysed samples is not distinguishable from locally produced ceramic from the Messina area. For almost all the samples, it has been possible to formulate a hypothesis about the production sites based on purely archaeological elements.

Multi-technique characterization of ancient findings from Gela (Sicily, Italy)

In the present study we carried out an extensive non-destructive and micro-destructive surface investigation on ancient decorated Sicilian samples of cultural interest, using a combination of different spectroscopic methods. In particular, the elemental composition, obtained by a handheld XRF analyser, acted as a valuable guideline for subsequent targeted sampling actions, thus minimizing the sampling damage. Hence, some questions not answered by XRF measurements (identification of some pigments, preparation layers, etc.) were subsequently resolved using Scanning Electron Microscopy coupled with Energy-Dispersive Spectrometry (SEM-EDS) and Fourier Transform Infrared absorbance spectroscopy (FT-IR). This multi-technique approach allowed us to provide useful information to establish the pigments and the production technique used by the craftsmen.

Decorated pottery study : Analysis of pigments by x-ray absorbance spectroscopy measurements

Characterization of pigments on decorated pottery fragments has been fully carried out by nondestructive x-ray absorbance spectroscopy (XAS). The samples were a series of pottery shards excavated from the archeological site of Caltagirone (Sicily, Italy), a well-known ceramic production center. Aesthetical criteria and morphological observations allowed us to attribute the samples to quite different historical periods, starting from the 18th century B.C. up to the 16th century A.D. An extensive time interval led us to suppose that different materials and techniques were used for the production of the ceramic paste and also for the preparation of pigments. XAS measurements were performed at the Cu and Fe K-edges. The analysis was carried out both in the near-edge (x-ray absorption near-edge spectroscopy, XANES) and in the extended (extended x-ray absorption fine structure, EXAFS) region. From the results, we observed Fe oxides as the main pigmenting agents in the most ancient fragment, while in the other c...