Current project:
Diffusion of water in clinopyroxene

Small amounts of water in deep-earth minerals such as clinopyroxene can significantly affect the melting temperature of rocks and therefore the movement of lithospheric plates and occurrence of, for instance, volcanic eruptions. Understanding how water behaves in these minerals will help to explain these phenomena and perhaps even provide a clock to measure the ascent rate of magma in volcanoes.

diopside viewed down c axis

Ti-in-zircon geothermometry

The concentration of titanium in zircon can give a rough estimate of the temperature at which a rock last reached thermodynamic equilibrium. I used computational techniques to show that the pressure correction for this geothermometer is likely on the order of 100 °C/GPa, and it may not be useful at all for systems that have experienced pressures about ~3.5 GPa (a depth of ~110 km).

Actinide-bearing zircon-structured solid solutions

The mineral zircon is very common in the natural world and has been considered for long-term disposal of actinides such as plutonium. I used computational techniques to calculate thermodynamic properties of seven related systems, including phase diagrams and ordering schemes. ZrSiO₄ and HfSiO₄ form a nearly ideal solid solution, but the miscibility of (Zr,Th)SiO₄, (Zr,U)SiO₄ (Zr,Pu)SiO₄,(Zr,Ce)SiO₄, (Hf,Pu)SiO₄, and (U,Th)SiO₄ was limited to no more than 12 mole % of the substituting cation.

UO₂ oxidation in the presence of corroding steel

Solid uranium dioxide (UO₂) is chemically similar to nuclear fuel. When UO₂ corrodes in air and water, the U is oxidized to form the highly mobile ion UO₂²⁺. My experiments indicated that surrounding the UO₂ with corroding steel may significantly slow the corrosion process.