Below are the projects past and present that comprise my PhD work. In addition to carrying out studies on conventional OH-based defects, I am also devoting significant effort to characterizing hydride-based defects in oxides, as this defect variety is virtually unexamined in earth science. My approach for studying both defect types employs a combination of theory and experiments, leaning heavily on DFT and infrared spectroscopy.

Hydrogen defects in reduced rutile 

Rutile (TiO) has long been known to incorporate hydrogen as OH-  groups when subjected to reducing conditions. More controversial is the possibility of hydride (H-) incorporation as a direct substitute for O2- ions. These hydride defects are predicted to be quite stable (see my DFT study here) but are not extensively characterized. I am currently carrying out experiments exploring the behavior of hydrogen in the oxygen-deficient rutile system.

The hydrogarnet substitution in stishovite 

Stishovite, a high-pressure polymorph of SiO with the rutile structure, is an important component of the deep earth. Recent experiments have shown that stishovite is capable of incorporating significant hydrogen through silicon vacancies coupled to OH- groups (a hydrogarnet-like defect). I conducted calculations to determine the likely configurations of this defect and simulate its spectroscopic behavior, with close agreement to experimental data. Read the paper here.

Hydride defects in titanate perovskites

Transition metal perovskites (especially from the group (Ca,Sr,Ba)TiO) are capable of incorporating high concentrations of hydride, sometimes to stoichiometric levels. These phases are not only technologically important, but are also structural analogues to the most abundant minerals in the deep earth. My current work on these materials is focused on inducing and characterizing the hydride defect in SrTiO. In particular, I am interested in establishing a frame of reference for detecting hydride in perovskites via vibrational spectroscopy.

Images from the lab: