Advancing Atom Probe Tomography of SrTiO$_3$: Measurement Methodology and Impurity Detection Limits

TL;DR

This paper develops a reliable atom probe tomography method for SrTiO$_3$, enabling detailed 3D atomic-scale chemical analysis and impurity detection, overcoming previous specimen fracture challenges.

Contribution

It introduces a metal coating technique that significantly improves STO specimen analysis success rate and achieves impurity detection limits as low as 0.7 at%.

Findings

High success rate in analyzing STO with metal coating

Detection of Nb impurities down to 0.7 at%

Establishment of a reliable APT methodology for STO

Abstract

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 show that by applying a thin metal coating to atom probe tips, STO specimens can be analyzed with nearly 100% success. Using this approach, we investigate both undoped STO and 1 at% Nb-doped STO, achieving sufficient sensitivity to detect Nb concentrations as low as 0.7 at%. This work establishes a reliable APT method for high-resolution chemical analysis of STO at the nanoscale.