Boundaries for martensitic transition of (7)Li under pressure.

ABSTRACT: Physical properties of lithium under extreme pressures continuously reveal unexpected features. These include a sequence of structural transitions to lower symmetry phases, metal-insulator-metal transition, superconductivity with one of the highest elemental transition temperatures, and a maximum followed by a minimum in its melting line. The instability of the bcc structure of lithium is well established by the presence of a temperature-driven martensitic phase transition. The boundaries of this phase, however, have not been previously explored above 3?GPa. All higher pressure phase boundaries are either extrapolations or inferred based on indirect evidence. Here we explore the pressure dependence of the martensitic transition of lithium up to 7?GPa using a combination of neutron and X-ray scattering. We find a rather unexpected deviation from the extrapolated boundaries of the hR3 phase of lithium. Furthermore, there is evidence that, above ?3?GPa, once in fcc phase, lithium does not undergo a martensitic transition.

SUBMITTER: Schaeffer AM 

PROVIDER: S-EPMC4557344 | biostudies-literature | 2015 Aug

REPOSITORIES: biostudies-literature