Reversible Control of the Mn Oxidation State in SrTiO Bulk Powders.

We demonstrate a low-temperature reduction method for exhibiting fine control over the oxidation state of substitutional Mn ions in strontium titanate (SrTiO) bulk powder. We employ NaBH as the chemical reductant that causes significant changes in the oxidation state and oxygen vacancy complexation with Mn dopants at temperatures <350°C where lattice reduction is negligible. At higher reduction temperatures, we also observe the formation of Ti in the lattice by diffuse-reflectance and low-temperature electron paramagnetic resonance (EPR) spectroscopy.