Structure and Electronic Properties of Sodium at Multi-Hundred GPa Pressures

Xuchen Gong, PhD Qualifying Exam

Tuesday, May 8, 2018
10 a.m.

Hopeman 224

At ambient conditions, sodium (Na) is an archetype of “nearly free electron” metals. Under compression, Na undergoes a series of phase transitions to low-symmetry structures, accompanied by a dramatic drop in the melting temperature. At 200 GPa, Na undergoes a conductor to insulator transition due to the valence electron localization at interstitial sites. There is no data beyond 200 GPa, and almost no data exist between 100-200 GPa. The proposed work will investigate the pressure-induced structural and electronic changes of Na at pressures approaching the TPa regime. The lattice and electronic structure of Na ramp-compressed at the OMEGA EP laser will be explored by x-ray diffraction and optical reflectance measurements respectively. Future work will improve the current diagnostics, adding temperature measurements and exploring other alkali metals.