Infrared optical absorption in low-spin Fe2+-doped SrTiO3

RB Comes, TC Kaspar, SM Heald… - Journal of Physics …, 2016 - iopscience.iop.org
Journal of Physics: Condensed Matter, 2016iopscience.iop.org
Band gap engineering in SrTiO 3 and related titanate perovskites has long been explored
due to the intriguing properties of the materials for photocatalysis and photovoltaic
applications. A popular approach in the materials chemistry community is to substitutionally
dope aliovalent transition metal ions onto the B site in the lattice to alter the valence band.
However, in such a scheme there is limited control over the dopant valence, and
compensating defects often form. Here we demonstrate a novel technique to controllably …
Abstract
Band gap engineering in SrTiO 3 and related titanate perovskites has long been explored due to the intriguing properties of the materials for photocatalysis and photovoltaic applications. A popular approach in the materials chemistry community is to substitutionally dope aliovalent transition metal ions onto the B site in the lattice to alter the valence band. However, in such a scheme there is limited control over the dopant valence, and compensating defects often form. Here we demonstrate a novel technique to controllably synthesize Fe 2+-and Fe 3+-doped SrTiO 3 thin films without formation of compensating defects by co-doping with La 3+ ions on the A site. We stabilize Fe 2+-doped films by doping with two La ions for every Fe dopant, and find that the Fe ions exhibit a low-spin electronic configuration, producing optical transitions in the near infrared regime and degenerate doping. The novel electronic states observed here offer a new avenue for band gap engineering in perovskites for photocatalytic and photovoltaic applications.
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