Ultra-incompressible phases of tungsten dinitride predicted from first principles

Hui Wang, Quan Li, Yinwei Li, Ying Xu, Tian Cui, Artem R. Oganov, Yanming Ma

Research output: Contribution to journalArticlepeer-review

60 Citations (Scopus)

Abstract

Using ab initio evolutionary methodology for crystal structure prediction, we have found two ultra-incompressible hexagonal structures of P 63 /mmc and P-6m2 of WN2, which are energetically much superior to previously proposed baddeleyite- and cotunnite-type structures and stable against decomposition into a mixture of W+ N2 or WN+1/2 N2. The calculated large bulk modulus (e.g., 411 GPa) and high hardness (36.8 GPa for P 63 /mmc and 36.6 GPa for P-6m2) reveal that they are ultra-incompressible and hard materials. The ultra- incompressibility is attributed to a staking of N-W-N "sandwiches" layers linked by strong covalent N-N single bonding. Thermodynamic study suggests that these phases are synthesizable at above 30 GPa.

Original languageEnglish
Article number132109
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume79
Issue number13
DOIs
Publication statusPublished - 1 Apr 2009
Externally publishedYes

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