Structure stability in the simple element sodium under pressure

Abstract

The simple alkali metal Na, that crystallizes in a body-centred cubic structure at ambient pressure, exhibits a wealth of complex phases at extreme conditions as found by experimental studies. The analysis of the mechanism of stabilization of some of these phases, namely, the low-temperature Sm-type phase and the high-pressure cI16 and oP8 phases, shows that they satisfy the criteria for the Hume-Rothery mechanism. These phases appear to be stabilized due to a formation of numerous planes in a Brillouin-Jones zone in the vicinity of the Fermi sphere of Na, which leads to the reduction of the overall electronic energy. For the oP8 phase, this mechanism seems to be working if one assumes that Na becomes divalent metal at this density. The oP8 phase of Na is analysed in comparison with the MnP-type oP8 phases known in binary compounds, as well as in relation to the hP4 structure of the NiAs-type.

References in corpus (8)

• Transparent dense sodium
• Superconductivity in lithium, potassium and aluminium under extreme pressure: A first-principles study
• On the constitution of sodium at higher densities
• Superconductivity and Lattice Instability in Compressed Lithium from Fermi Surface Hot Spots
• Interstitial Electronic Localization
• Structure, elastic moduli and thermodynamics of sodium and potassium at ultra-high pressures
• Simple Metals at High Pressure
• Nesting Induced Peierls-type Instability for Compressed Li-CI16

Cited by in corpus (11)

• Pressure-induced s-band ferromagnetism in alkali metals
• Electronic and structural ground state of heavy alkali metals at high pressure
• Complex structures in the Au-Cd alloy system: Hume-Rothery mechanism as origin
• Simple metal and binary alloy phases based on the hcp structure: electronic origin of distortions and superlattices
• Simple Metals at High Pressure
• Potassium under pressure: electronic origin of complex structures
• Transformations of Phosphorus under Pressure from Simple Cubic to Simple Hexagonal Structures via Incommensurately Modulations: Electronic Origin
• Electronic origin of melting T-P curves of alkali metals with negative slope and minimum
• Complex structures of dense lithium: electronic origin
• Simple metal binary phases based on the body centered cubic structure: electronic origin of distortions and superlattices
• Electronic origin of the orthorhombic Cmca structure in compressed elements and binary alloys