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This work investigates element mobility and deformation mechanisms in sulphide-bearing quartz veins associated with a strike-slip fault exposed in the ONKALO™ Finnish deep repository for spent nuclear fuel (Olkiluoto Island, southwest Finland). It combines petrography, trace element mapping by Laser Ablation Inductively Coupled Plasma Time-of-Flight Mass Spectrometry (LA-ICP-TOFMS) and Electron Backscattered Diffraction (EBSD) analysis of representative microstructures. The fault core was reactivated by brittle deformation episodes assisted by hydrothermal fluid batches with distinct trace element signatures. LA-ICP-TOFMS element distribution maps and EBSD on sulphides reveal local, syn-deformational intragrain enrichment of primary and secondary elements (i.e., As, Co, Cu, Ag, Sn, Sb, Pb, Se, In, Te). Trace element enrichments occur by a combination of microscale plastic distortions and microfracturing at the reaction fronts. Fluid ingress along microcracks enhanced chemical replacement of pyrite that combined with element diffusion along dislocations and tilt boundaries controlled trace element mobility in sulphides at the small scale. At the scale of the vein system, the competence contrast between inclusions of soft sulphides in the harder host quartz may have favored local fracture nucleation and fluid flow.

The solid solutions Bi1-xSmxFeO3 with chemical composition across the morphotropic phase boundary region specific for rhombohedral - orthorhombic structural transition were investigated by X-ray diffraction, electron microscopy and magnetometry. Structural measurements showed a concentration driven transition from the single phase rhombohedral structure to the single phase nonpolar orthorhombic structure through the formation of antipolar orthorhombic phase which coexists with the rhombohedral phase in the compounds with x < 0.15 followed by a coexistence with nonpolar orthorhombic phase in the compounds with x