Brno University of Technology

About: Brno University of Technology is a education organization based out in Brno, Czechia. It is known for research contribution in the topics: Computer science & Fracture mechanics. The organization has 6339 authors who have published 15226 publications receiving 194088 citations. The organization is also known as: Vysoké učení technické v Brně & BUT.

First-principles study of magnetism at grain boundaries in iron and nickel

Abstract: The geometric and magnetic structures of fully relaxed symmetrical tilt $\ensuremath{\Sigma}5(310)$ grain boundaries (GBs) in iron and $\ensuremath{\Sigma}5(210)$ GBs in nickel have been investigated using density-functional theory. We found for both GBs an enhancement of the local magnetic moments of atoms in the GB plane ($2.55\text{ }{\ensuremath{\mu}}_{B}$ for iron and $0.67\text{ }{\ensuremath{\mu}}_{B}$ for nickel) which is correlated with the larger local atomic volume compared to the bulk. At larger distances from the GB the variation of the local magnetic moments follows the changes in the exchange splitting in the spin-polarized local density of states imposed by the local variations in the atomic geometry. When Si and Sn impurity atoms in interstitial or substitutional positions appear at the $\ensuremath{\Sigma}5(310)$ GB in iron, the local magnetic moments of iron atoms are reduced for silicon and almost unchanged for tin. We also calculated the segregation enthalpies of both impurities and confirmed the experimental fact that silicon is a substitutional and tin an interstitial segregant; the calculated values of segregation enthalpy are in good agreement with experiment.

Investigation of heavy-metal accumulation in selected plant samples using laser induced breakdown spectroscopy and laser ablation inductively coupled plasma mass spectrometry

Abstract: Single-pulse Laser-Induced Breakdown Spectroscopy (LIBS) and Laser-Ablation Inductively Coupled Plasma Mass-Spectrometry (LA-ICP-MS) were applied for mapping the silver and copper distribution in Helianthus Annuus L. samples treated with contaminant in controlled conditions. For Ag and Cu detection the 328.07 nm Ag(I) and 324.75 nm Cu(I) lines were used, respectively. The LIBS experimental conditions (mainly the laser energy and the observation window) were optimized in order to avoid self-absorption effect in the measured spectra. In the LA-ICP-MS analysis the Ag 107 and Cu 63 isotopes were detected. The capability of these two analytical techniques for high-resolution mapping of selected trace chemical elements was demonstrated.