Abstract: Terrestrial magnetic fields are generated by movement of electrically conductive fluid within an iron-rich core. The thermal conductivity of iron and iron alloys have been used to call into question the time of crystallization of Earth's inner core. Because iron meteorites serve as natural composition analogs for terrestrial cores, we present room temperature measurements of thermal conductivity of Canyon Diablo iron meteorite up to 40 GPa using ultrafast pump-probe spectroscopy based on time-domain thermoreflectance combined with diamond anvil cell techniques. Results show a decrease from 45 W/mK at ambient conditions to nearly 18 W/mK as pressure increases to 20 GPa providing evidence the pressure-induced bcc-hcp (α-ε) crystal-structure phase transition of pure iron is not affected by the presences of impurities for abundances present in natural meteorites. Our measurements are consistent with the tendency of alloying to decrease thermal conductivity. Additionally, we present thermal conductivity measurements of the shock window lithium-fluoride (LiF) up to 36 GPa at room temperature. The thermal properties of LiF are necessary for correcting temperatures measured during dynamic compression experiments on opaque samples (e.g., iron). Obtaining measurements on natural samples and shock window materials help constrain the effects of alloying and impurities on core structure and evolution.

Bio: Mercedes is a 5th PhD candidate in the department of Earth and Planetary Science at UC Berkeley, where she is part of Professor Jeanloz's mineral physics group. Her research is centered on investigating the role of thermal transport in the structural evolution of planetary cores, specifically by measuring the thermal conductivity of iron meteorites at pressures relevant to planetary interiors. She is interested in developing experimental techniques for measuring transport properties at extreme conditions, utilizing ultrafast pump-probe spectroscopy and laser-heated diamond cell methods. With her experience as a first-generation college graduate, she is dedicated to creating pathways for others to pursue higher education. When outside the lab, Mercedes enjoys reading and is the captain of a women's soccer team.