Reversible Control of the Mn Oxidation State in SrTiO 3 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...

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Bibliographic Details
Published inFrontiers in chemistry Vol. 7; p. 353
Main Authors Mansoor, Haneen, Harrigan, William L, Lehuta, Keith A, Kittilstved, Kevin R
Format Journal Article
LanguageEnglish
Published Switzerland 2019
Subjects
oxidation state
inorganic materials
electron paramagnetic resonance
strontium titanate
manganese
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Summary: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. In addition to Mn , Mn , and the Mn complex with an oxygen vacancy, we also observe a sharp resonance in the EPR spectrum of heavily reduced Mn-doped SrTiO . This sharp signal is tentatively assigned to surface superoxide ion that is formed by the surface electron transfer reaction between Ti and O . The ability to control the relative amounts of various paramagnetic defects in SrTiO provides many possibilities to study in a model system the impact of tunable dopant-defect interactions for spin-based electronic applications or visible-light photocatalysis.
ISSN:2296-2646
2296-2646