X-ray absorption experiments on $3d$ transition-metal tracer ions in ${\text{SrTiO}}_3$ are presented. The absorption spectra of the tracer-ion changed upon reduction in the ${\text{SrTiO}}_3$. This change is due to an oxygen vacancy created at the tracer-ion site. This finding is supported by density-functional theory calculations, which prove that the oxygen vacancies preferentially are created at the tracer-ion sites. Using the chemical sensitivity of x-ray absorption spectroscopy, tracer ions can be used to detect oxygen vacancies in ${\text{SrTiO}}_3$ and possibly in other oxide systems.

• Received 9 November 2009

DOI:https://doi.org/10.1103/PhysRevB.80.212103