Local environment and oxidation state of Mn impurity in SrTiO3 determined from XAFS data

TL;DR

This study uses XAFS spectroscopy to analyze the local environment and oxidation states of Mn impurities in SrTiO3, revealing site-specific oxidation states and off-center displacement influenced by preparation conditions.

Contribution

It demonstrates how X-ray absorption near-edge structure analysis can determine Mn site occupancy and oxidation states in doped SrTiO3, providing insights into impurity incorporation mechanisms.

Findings

Mn substituting Ti is Mn4+ and on-center

Mn substituting Sr is Mn2+ and off-center by ~0.32 Å

XANES can determine Mn site ratios

Abstract

The local environment and oxidation state of Mn impurity in strontium titanate doped with 3% Mn were studied by X-ray absorption fine structure spectroscopy. The influence of the preparation conditions on the incorporation of the impurity into the $A$ and $B$ sites was studied. It was established that Mn ions substituting for Ti are in the Mn$^{4+}$ oxidation state and on-center. Mn ions substituting for Sr are in the Mn$^{2+}$ oxidation state, are off-center and displaced from the lattice sites by $\sim$0.32 {\AA}. It was demonstrated that studies of the X-ray absorption near-edge structure can be used to determine the concentration ratio of Mn atoms located at the $A$ and $B$ sites.