Lithium, compression and high-pressure structure.

Area of Science:

• Materials Science
• Condensed Matter Physics
• High-Pressure Physics

Background:

• Understanding phase transitions in elemental metals under extreme conditions is crucial for materials science.
• Lithium's structural behavior at high pressures provides insights into alkali metal physics.

Purpose of the Study:

• To investigate the structural phase transition of lithium under high pressure.
• To determine the properties of lithium's body-centered cubic (bcc) and face-centered cubic (fcc) phases.

Main Methods:

• High-pressure experiments were conducted on lithium.
• Structural transformations were analyzed at specific pressure and temperature points.

Main Results:

• Lithium transforms from a bcc to an fcc structure at 6.9 gigapascals (GPa) and 296 Kelvin.
• The fcc structure is 0.25% denser than the bcc structure at 6.9 GPa, with a relative volume of 0.718 for bcc.
• Bulk modulus and its pressure derivative were calculated for both phases, indicating stiffer fcc structure.

Conclusions:

• The study identifies the critical pressure for the bcc-fcc phase transition in lithium.
• Extrapolation suggests a triple point for lithium at approximately 15 GPa and 500 K.
• These findings contribute to the understanding of high-pressure phase diagrams of elemental metals.