Advancing Atom Probe Tomography of SrTiO3: Measurement Methodology and Impurity Detection Limits.

Strontium titanate (STO) possesses promising properties for applications in thermoelectricity, catalysis, fuel cells, and more, but its performance is highly dependent on stoichiometry and impurity levels. While atom probe tomography (APT) can provide detailed three-dimensional atomic-scale chemical information, STO specimens have been challenging to analyze due to premature specimen fracture. In this study, we demonstrate that applying a thin metal coating to atom probe tips leads to a substantial increase in measurement yield, with dataset sizes improving by more than an order of magnitude. Using this approach, we investigate both undoped STO and 1 at% Nb-doped STO, demonstrating sufficient sensitivity to detect the presence of Nb at nominal concentrations as low as 0.75 at%. This work establishes a reliable APT method for high-resolution chemical analysis of STO at the nanoscale.