Neutron-based analyses of three Bronze Age metal objects: a closer look at the Buggenum, Jutphaas and Escharen artefacts

Three important Bronze Age copper-alloy artefacts from the permanent exhibition of the National Museum of Antiquity in Leiden (NL) have been studied by neutron-based methods. These artefacts are known as the Buggenum sword, the Jutphaas dirk, and the Escharen double axe. All three objects have been studied with neutron resonance capture analysis (NRCA), a non-destructive method to determine the bulk elemental compositions. The Buggenum sword is also studied with time-of-flight neutron diffraction (TOF-ND) giving additional information about crystalline properties and internal material structures, and neutron tomography (NT), showing details of the construction of this sword and voids inside the material. The composition of the Jutphaas dirk is compared with the compositions of two other dirks belonging to the group of six Plougrescant-Ommerschans (PO) ceremonial dirks. The Escharen double axe, identified as being of the Zabitz type, variant Westeregeln, is a rare object in the Low Countries. It is compared to finds from Central Europe. The results for all three objects are discussed with regards to their archaeological contexts and their relation to other finds

Tuning the phase transition in transition-metal-based magnetocaloric compounds

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Neutron-based analyses of three Bronze Age metal objects: a closer look at the Buggenum, Jutphaas and Escharen artefacts

Artefact studie

Tuning the phase transition in transition-metal-based magnetocaloric compounds

Neutron-diffraction experiments on the (Mn,Fe)2(P,Si)-type compounds have shown a site preference of Si atoms in the hexagonal structure. The degree of ordering of Si depends on the Si/P ratio, while it is independent of the Mn/Fe ratio. The ferromagnetic-paramagnetic magnetoelastic transition is closely related to the size of the magnetic moment on the 3f site. A preferred occupation of Si atoms on the 2c site stabilizes and decreases the magnetic moment on the 3f and 3g site, respectively, which is supported by our first-principles density functional theory calculations. This effect, together with the contribution from the Si substitution-induced changes in the interatomic distances, leads to a phase transition that is tunable in temperature and degree of first order in Mn1.25Fe0.70P1?xSix compounds. These results provide us with further insight into the relationship between the magnetoelastic phase transition and the local atomic coordination.RST/Radiation, Science and TechnologyApplied Science