pubmed.ncbi.nlm.nih.gov

Transparent dense sodium - PubMed

  • ️Thu Jan 01 2009

. 2009 Mar 12;458(7235):182-5.

doi: 10.1038/nature07786.

Affiliations

Transparent dense sodium

Yanming Ma et al. Nature. 2009.

Abstract

Under pressure, metals exhibit increasingly shorter interatomic distances. Intuitively, this response is expected to be accompanied by an increase in the widths of the valence and conduction bands and hence a more pronounced free-electron-like behaviour. But at the densities that can now be achieved experimentally, compression can be so substantial that core electrons overlap. This effect dramatically alters electronic properties from those typically associated with simple free-electron metals such as lithium (Li; refs 1-3) and sodium (Na; refs 4, 5), leading in turn to structurally complex phases and superconductivity with a high critical temperature. But the most intriguing prediction-that the seemingly simple metals Li (ref. 1) and Na (ref. 4) will transform under pressure into insulating states, owing to pairing of alkali atoms-has yet to be experimentally confirmed. Here we report experimental observations of a pressure-induced transformation of Na into an optically transparent phase at approximately 200 GPa (corresponding to approximately 5.0-fold compression). Experimental and computational data identify the new phase as a wide bandgap dielectric with a six-coordinated, highly distorted double-hexagonal close-packed structure. We attribute the emergence of this dense insulating state not to atom pairing, but to p-d hybridizations of valence electrons and their repulsion by core electrons into the lattice interstices. We expect that such insulating states may also form in other elements and compounds when compression is sufficiently strong that atomic cores start to overlap strongly.

PubMed Disclaimer

Comment in

Similar articles

Cited by

References

    1. Phys Rev Lett. 2001 Mar 26;86(13):2830-3 - PubMed
    1. Phys Rev Lett. 2008 Aug 15;101(7):075703 - PubMed
    1. J Chem Phys. 2006 Jun 28;124(24):244704 - PubMed
    1. Phys Rev Lett. 2005 May 13;94(18):185502 - PubMed
    1. Phys Rev Lett. 2003 Oct 17;91(16):167001 - PubMed

Publication types

LinkOut - more resources