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arXiv · 1510.05965

Infrared Optical Absorption in Low-spin Fe$^{2+}$-doped SrTiO${}_{3}$

Ryan B. Comes·Tiffany C. Kaspar·Steve M. Heald·Mark E. Bowden·Scott A. Chambers
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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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Ryan B. Comes, Tiffany C. Kaspar, Steve M. Heald, Mark E. Bowden, Scott A. Chambers. 2015-10-20. Infrared Optical Absorption in Low-spin Fe$^{2+}$-doped SrTiO${}_{3}$. https://doi.org/10.1088/0953-8984%2F28%2F3%2F035901

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