Hydrogen-related defects in SnO$_{2}$

Symmetry arguments along with a mass-and spring analysis of infrared absorption experiments made with polarized light on OH defects in SnO$_{2}$ yield significant insights into the possible structures of one- and two-OH defects that have been observed recently [1]. Namely, a two-OH defect must involve symmetry-equivalent OH sites, and the axes of both one-and two-OH defects are only slightly displaced from the perpendicular to the c-axis of the rutile structure. Such results cannot be explained by models involving one or two H trapped at a Sn vacancy. Rather, they are consistent with OH defects associated with either a metal atom substituting for Sn, or an interstitial metal atom (such as Sn). Results of detailed quantum-mechanical calculations [2] using CRYSTAL06 are consistent with OH structures involving a Sn interstitial. \\[4pt] [1] Figen Bekisli \textit{et al.,} Phys. Rev. B \textbf{84}, 035213 (2011). \\[0pt] [2] R. Dovesi \textit{et al.}, \textbf{\textit{Crystal06 User's Manual}}, Univ. of Torino, Torino, 2006.