Site Dependency of the High Conductivity of Ga ₂ In ₆ Sn ₂ O ₁₆ : The Role of the 7-Coordinate Site

Journal Article · 10 November 2015 · Chemistry of Materials

DOI: https://doi.org/10.1021/acs.chemmater.5b03790 · OSTI ID:1261489

Rickert, Karl ^[1]; Huq, Ashfia ^[2]; Lapidus, Saul H. ^[3]; Wustrow, Allison ^[1]; Ellis, Donald E. ^[1]; Poeppelmeier, Kenneth R. ^[1]

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1. Northwestern Univ., Evanston, IL (United States)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
3. Argonne National Lab. (ANL), Argonne, IL (United States)

In 6-coordinated cation sites, we find that it is the fundamental building block of the most effective transparent conducting oxides. Ga₂In₆SnO₁₆, however, maintains 4-, 6-, 7-, and 8-coordinated cation sites and still exhibits desirable transparency and high conductivity. To investigate the potential impact of these alternative sites, we partially replace the Sn in Ga₂In₆Sn₂O₁₆ with Ti, Zr, or Hf and use a combined approach of density functional theory-based calculations, X-ray diffraction, and neutron diffraction to establish that the substitution occurs preferentially on the 7-coordinate site. Conversely to Sn, the empty d orbitals of Ti, Zr, and Hf promote spd covalency with the surrounding oxygen, which decreases the conductivity. Pairing the substitutional site preference with the magnitude of this decrease demonstrates that the 7-coordinate site is the V major contributor to conductivity. The optical band gaps, in contrast, are shown to be site-independent and composition-dependent. After all 7-coordinate Sn has been replaced, the continued substitution of Sn results in the formation of a 7-coordinate In antisite or replacement of 6-coordinate Sn, depending on the identity of the d(0) substitute.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
• Grant/Contract Number: AC05-00OR22725; FG02-08ER46536
• OSTI ID: 1261489
• Journal Information: Chemistry of Materials, Journal Name: Chemistry of Materials Journal Issue: 23 Vol. 27; ISSN 0897-4756
• Publisher: American Chemical Society (ACS)Copyright Statement
• Country of Publication: United States
• Language: English