Cryogenic vitrification and 3D serial sectioning using high resolution cryo‐FIB SEM technology for brine‐filled grain boundaries in halite: first results

The structure of brine films in grain boundaries of halite has been the subject of much controversy over the past 20 years; although a number of innovative methods have been developed to study these structures, much is still unknown and fundamental information is missing. In this study, we investigated different methods of plunge‐freezing to vitrify the brine fill of grain boundaries for natural salt polycrystal. This was followed by a preliminary study of the 3D morphology of a vitrified grain boundary in a natural rock salt sample with a focused ion beam (FIB) excavation system. We have shown that brine‐filled grain boundaries in rock salt can be efficiently well frozen when dimensions are less than about 1 mm. Coupled with an ion beam tool, cryo‐SEM allows 3D observation of the well‐frozen grain boundaries in large volumes and high resolution. Initial results of brine‐filled natural halite grain boundaries show non‐faceted crystal–brine interfaces and unexpectedly low dihedral angles at room temperature and pressure.     

Technological examination of Neolithic-Bronze Age pottery from central and southeast Europe and from the Near East

Scanning electron microscopy is used to examine sequences of pottery sherds from central and southeast Europe, Greece and the Near East spanning the period from the Neolithic to the Bronze Age, in order to obtain information on the ceramic technologies employed in antiquity. On the basis of the vitrification observed and the chemical composition, the types of clay and firing procedures (temperature and atmosphere) employed in the manufacture of the pottery are defined. Two under-lying trends in the associated ceramic technologies are thus identified. The first is based on the use of non-calcareous or “unstable” calcareous clays fired in a reducing atmosphere at temperatures below 800 °C and the second on the use of “stable” calcareous clays fired in an oxidizing atmosphere at temperatures in excess of 800 °C.