High-Pressure Melt Curve and Phase Diagram of Lithium

Mungo Frost; Jongjin B Kim; Emma E McBride; J Ryan Peterson; Jesse S Smith; Peihao Sun; Siegfried H Glenzer

doi:10.1103/PhysRevLett.123.065701

High-Pressure Melt Curve and Phase Diagram of Lithium

Phys Rev Lett. 2019 Aug 9;123(6):065701. doi: 10.1103/PhysRevLett.123.065701.

Authors

Mungo Frost¹, Jongjin B Kim¹, Emma E McBride¹, J Ryan Peterson^{1

2}, Jesse S Smith³, Peihao Sun^{1

2}, Siegfried H Glenzer¹

Affiliations

¹ SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA.
² Physics Department, Stanford University, 382 Via Pueblo Mall, Stanford, California 94305, USA.
³ High Pressure Collaborative Access Team, X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.

PMID: 31491150
DOI: 10.1103/PhysRevLett.123.065701

Abstract

We investigate the phase diagram of lithium at temperatures of 200 to 400 K, to pressures over 100 GPa using x-ray diffraction in diamond anvil cells, covering the region in which the melting curve is disputed. To overcome degradation of the diamond anvils by dense lithium we utilize a rapid compression scheme taking advantage of the high flux available at modern synchrotrons. Our results show the hR1 and cI16 phases to be stable to higher temperature than previously reported. The melting minima of lithium is found to be close to room temperature between 40 and 60 GPa, below which the solid is crystalline. Analysis of the stability fields of the cI16 and oC88 phases suggest the existence of a triple point between these and an undetermined solid phase at 60 GPa between 220 and 255 K.