Boundaries for martensitic transition of (7)Li under pressure.
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.
Department of Physics and Astronomy, University of Utah, 115S 1400E, Salt Lake City, Utah 84112, USA.
Anne Marie
AM
Schaeffer
Department of Physics and Astronomy, University of Utah, 115S 1400E, Salt Lake City, Utah 84112, USA.
Weizhao
W
Cai
Department of Physics and Astronomy, University of Utah, 115S 1400E, Salt Lake City, Utah 84112, USA.
Ella
E
Olejnik
Quantum Condensed Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Jamie J
0000000317718409
JJ
Molaison
HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, Illinois 60439, USA.
Stanislav
S
Sinogeikin
Quantum Condensed Matter Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Antonio M
AM
dos Santos
Department of Physics and Astronomy, University of Utah, 115S 1400E, Salt Lake City, Utah 84112, USA.
Shanti
S
Deemyad