Complexities of grain boundaries and atom probe tomography

The authors of this paper*, led by Oxford Materials, developed a computational method to systematically calculate Gibbsian interfacial excess across grain boundaries, to measure excess solute atoms at interfaces compared to matrix concentrations.  The validity of this method was tested using simulated Atom Probe Tomography volumes.

The computational method was then applied to analyse grain boundaries across three K-doped BaFe₂As₂ samples.  Segregation of As, Ba K as well as impurities of O, Na and Sb were found at grain boundaries at varying levels.  The potential links between segregation behaviour, microstructure, and the critical current densities are investigated and discussed in this paper.

*'Revealing the complex chemistry of grain boundaries in K-doped BaFe₂As₂ with atom probe tomography' (Journal of Materials Science & Technology).