Electron backscattering diffraction as a complementary analytical approach to the microstructural characterization of ancient materials by electron microscopy

Since the development of electron backscattering diffraction (EBSD), scanning electron microscopy (SEM) has become a powerful tool for characterizing the local crystallography of bulk materials at the nanoscale. Although EBSD is now a well-established characterization method in materials science, it has rarely been used in art and archaeology, and nearly exclusively in metallic materials. However, EBSD could also be exploited to characterize ancient materials and to highlight their local crystallography (e.g., in the study of natural or artificial pigments). We discuss the potential of EBSD, as outlined in studies and from its application with an ancient material - Egyptian blue - in identification of crystalline phases, drawing phase maps, and the extraction of several microstructural parameters (e.g., the grain size and the aspect-ratio distribution of phases).The authors acknowledge funding by CTQ2011-24882 (Ministerio de Ciencia e Innovación) and MAT2012-30763 (Ministerio de Economía y Competitividad) projects, which are financed by the Spanish Government and the Federal program of the European Union.Peer Reviewe

Characterization of islamic ceramic production techniques in northeast iberian peninsula: The case of medieval albarracin (spain)

Ceramic objects found in the Islamic Taifa of Albarracin (Spain), 12th century CE, were studied to ascertain the main characteristics and influences of its manufacture. Production centers even from small kingdoms can add new insights in medieval ceramic technology. Several types of decorated ceramics, such as tin-opacified glazed, monochrome glazed and cuerda seca, were investigated. Ceramic bodies were analyzed by ICP-Optical Emission Spectrometry, and glazes were studied by Scanning Electron Microscopy with Energy Dispersive X-ray Spectrometry. All the ceramic bodies showed the use of Ca-rich pastes, although three groups could be distinguished and related to their decoration. Lead and silicon were the main components of the glazes, as well as scattered tin oxide in the case of white or green opacified glazes. Some features, such as calcareous bodies, double firing for tin-opacified glazes, glaze components, and coloring oxides, were common in Albarracin samples and other Islamic production centers in the Iberian Peninsula. However, some differences were also highlighted in lead/silica proportions and cuerda seca decoration, and several influences from northern or southern pottery centers. Lead isotope ratios, measured by ICP-Quadrupole Mass Spectrometry, revealed two different sources or suppliers of lead raw materials according to the type of glaze to be prepared. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Exploring the boundaries in the analysis of large particles by single particle inductively coupled plasma mass spectrometry: application to nanoclays

The analysis of microparticles by single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) requires sample introduction systems that guarantee transport efficiencies similar to those obtained with dissolved standards across the size range covered. The utilization of a nebulisation system based on a linear pass spray chamber and a micronebuliser is discussed and optimized for the introduction of large inorganic particles. Limitations caused by incomplete ionisation or the counting limit of detectors affecting particle size characterisation are also considered. The procedure developed has been applied to the characterisation of suspensions of a natural clay (kaolinite), with a thickness in the range of a few nanometers and lateral dimensions up to 1 mu m. The application of different sensitivity conditions by the modification of the ion transmission allowed us to cover the whole size range of the suspension monitoring the Al-27 isotope and achieve a quantitative mass recovery with respect to ICP-MS analysis. Finally, the migration of nanoclays (montmorillonite) from food containers and their detection by SP-ICP-MS are presented. The results have been compared to those obtained by TEM, showing that nanoclays migrated from the containers into water

Detection, size characterization and quantification of silver nanoparticles in consumer products by particle collision coulometry

Silver nanoparticles (AgNPs) are widely used in industrial and consumer products owing to its antimicrobial nature and multiple applications. Consequently, their release into the environment is becoming a big concern because of their negative impacts on living organisms. In this work, AgNPs were detected at a potential of + 0.70 V vs. Ag/AgCl reference electrode, characterized, and quantified in consumer products by particle collision coulometry (PCC). The electrochemical results were compared with those measured with electron microscopy and single-particle inductively coupled plasma mass spectrometry. The theoretical and practical peculiarities of the application of PCC technique in the characterization of AgNPs were studied. Reproducible size distributions of the AgNPs were measured in a range 10–100 nm diameters. A power allometric function model was found between the frequency of the AgNPs collisions onto the electrode surface and the number concentration of nanoparticles up to a silver concentration of 1010 L-1 (ca. 25 ng L-1 for 10 nm AgNPs). A linear relationship between the number of collisions and the number concentration of silver nanoparticles was observed up to 5 × 107 L-1. The PCC method was applied to the quantification and size determination of the AgNPs in three-silver containing consumer products (a natural antibiotic and two food supplements). The mean of the size distributions (of the order 10–20 nm diameters) agrees with those measured by electron microscopy. Graphical abstract: [Figure not available: see fulltext.]

Evaluation of hydrodynamic chromatography coupled to inductively coupled plasma mass spectrometry for speciation of dissolved and nanoparticulate gold and silver

In this study, hydrodynamic chromatography coupled to inductively coupled plasma mass spectrometry has been evaluated for the simultaneous determination of dissolved and nanoparticulate species of gold and silver. Optimization of mobile phase was carried out with special attention to the column recovery of the different species and the resolution between them. Addition of 0.05 mM penicillamine to the mobile phase allowed the quantitative recovery of ionic gold and gold nanoparticles up to 50 nm, whereas 1 mM penicillamine was necessary for quantitative recovery of ionic silver and silver nanoparticles up to 40 nm. The resolution achieved between ionic gold and 10-nm gold nanoparticles was 0.7, whereas it ranged between 0.31 and 0.93 for ionic silver and 10-nm silver nanoparticles, depending on the composition of mobile phase. Best-case mass concentration detection limits for gold and silver species were 0.05 and 0.75 µg L-1, respectively. The developed methods allowed the simultaneous detection of nanoparticulate and dissolved species of gold and silver in less than 10 min. Size determination and quantification of gold and silver species were carried out in different dietary supplements, showing good agreement with the results obtained by electron microscopy and total and ultrafiltrable contents, respectively. Due to the attainable resolution, the quality of the quantitative results is affected by the relative abundance of nanoparticulate and dissolved species of the element and the size of the nanoparticles if present. Graphical abstract: [Figure not available: see fulltext.

The use of micro-XRD for the study of glaze color decorations

The compounds responsible for the colours and decorations in glass and glazed ceramics include: colouring agents (transition metal ions), pigments (micro-and nano-precipitates of compounds that either do not dissolve or recrystallize in the glassy matrix) and opacifiers (microcrystalline compounds with high light scattering capability). Their composition, structure and range of stability are highly dependent not only on the composition but also on the procedures followed to obtain them. Chemical composition of the colorants and crystallites may be obtained by means of SEM-EDX and WDX. Synchrotron Radiation micro-X-ray Diffraction has a small beam size adequate (10 to 50 microns footprint size) to obtain the structural information of crystalline compounds and high brilliance, optimal for determining the crystallites even when present in low amounts. In addition, in glass decorations the crystallites often appear forming thin layers (from 10 to 100 micrometers thick) and they show a depth dependent composition and crystal structure. Their nature and distribution across the glass/glazes decorations gives direct information on the technology of production and stability and may be related to the color and appearance. A selection of glass and glaze coloring agents and decorations are studied by means of SR-micro- XRD and SEM-EDX including: manganese brown, antimony yellow, red copper lusters and cobalt blue. The selection includes Medieval (Islamic, and Hispano Moresque) and renaissance tin glazed ceramics from the 10th to the 17th century AD

Organic residues in archaeology - the highs and lows of recent research

YesThe analysis of organic residues from archaeological materials has become increasingly important to our understanding of ancient diet, trade and technology. Residues from diverse contexts have been retrieved and analysed from the remains of food, medicine and cosmetics to hafting material on stone arrowheads, pitch and tar from shipwrecks, and ancient manure from soils. Research has brought many advances in our understanding of archaeological, organic residues over the past two decades. Some have enabled very specific and detailed interpretations of materials preserved in the archaeological record. However there are still areas where we know very little, like the mechanisms at work during the formation and preservation of residues, and areas where each advance produces more questions rather than answers, as in the identification of degraded fats. This chapter will discuss some of the significant achievements in the field over the past decade and the ongoing challenges for research in this area.Full text was made available in the Repository on 15th Oct 2015, at the end of the publisher's embargo period

Gas chromatography/mass spectrometry and pyrolysis-gas chromatography/mass spectrometry for the chemical characterisation of modern and archaeological figs (Ficus carica)

Gas chromatography/mass spectrometry (GC/MS) after alkaline hydrolysis, solvent extraction and trimethylsilylation, and analytical pyrolysis using hexamethyldisilazane (HMDS) for in-situ derivatisation followed by gas chromatographic/mass spectrometric analysis (Pyrolysis-silylation-GC/MS) were used to investigate the hydrolysable and soluble constituents, and the polymerised macromolecules of an archaeological fig (Ficus carica) recovered in Zaragoza (Spain), as well as of modern figs. The main aim was to study the compositional alterations undergone by the fig tissues in a particular archaeological environment: the fig was in a vessel and covered by a layer of a mixture of orpiment and gypsum. A comparison between the GC/MS results from modern and archaeological figs revealed that degradative reactions took place, leading to the disappearance/depletion of reactive (unsaturated fatty acids) and sensitive compounds (phytosterols and triterpenes). Py-silylation-GC/MS data provided evidence of a significant degradation of the saccharide and lipid components of the fig tissue, which left a residue enriched in polyphenols and polyesters