Evolving Structural Diversity and Metallicity in Compressed Lithium Azide

Dasari L. V. K. Prasad, N. W. Ashcroft, Roald Hoffmann

Research output: Contribution to journalArticlepeer-review

41 Scopus citations

Abstract

In pursuit of new stable nitrogen-rich phases and of a possible insulator-metal transition, the ground-state electronic structure of lithium azide, LiN3, is investigated from 1 atm to 300 GPa (∼2-fold compression) using evolutionary crystal structure exploration methods coupled with density functional theoretical calculations. Two new LiN3 phases, containing slightly reduced and well-separated N2 units, are found to be enthalpically competitive with the known lithium azide crystal structure at 1 atm. At pressures above 36 GPa nitrogen-rich assemblies begin to evolve. These incorporate NN bond formation beyond that in N2 or N3 -. N6 rings and infinite one-dimensional linear nitrogen chains (structural analogues to polyacetylene) appear. Above 200 GPa quasi-one- and two-dimensional extended puckered hexagonal and decagonal nitrogen layers emerge. The high-pressure phase featuring linear chains may be quenchable to P = 1 atm. With increasing pressure the progression in electrical conductivity is from insulator to metal. © 2013 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)20838-20846
Number of pages9
JournalThe Journal of Physical Chemistry C
Volume117
Issue number40
DOIs
StatePublished - Sep 30 2013
Externally publishedYes

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