Thermodynamic and Mechanical Stabilities of Tantalum Nitride

Chao Jiang, Zhijun Lin, and Yusheng Zhao
Phys. Rev. Lett. 103, 185501 – Published 28 October 2009

Abstract

We perform first-principles density functional calculations on a newly discovered tantalum nitride with an orthorhombic U2S3 structure to assess its thermodynamic and mechanical stabilities. Our random search unveils a tetragonal Ta2N3 structure that is energetically more favorable than an orthorhombic Ta2N3 at zero pressure. We predict that the tetragonal Ta2N3 transforms into the orthorhombic phase above a relatively low pressure of 7.7 GPa. Single-crystal elastic constant calculations reveal that orthorhombic Ta2N3 is mechanically unstable because of a negative c66. Our calculations suggest that minor oxygen substitution for nitrogen plays an important role in stabilizing the orthorhombic Ta2N3 structure.

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  • Received 1 August 2009

DOI:https://doi.org/10.1103/PhysRevLett.103.185501

©2009 American Physical Society

Authors & Affiliations

Chao Jiang1,*, Zhijun Lin2,†, and Yusheng Zhao2,‡

  • 1Structure/Property Relations Group (MST-8), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
  • 2LANSCE—Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

  • *chao@lanl.gov
  • zlin@lanl.gov
  • yzhao@lanl.gov

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Vol. 103, Iss. 18 — 30 October 2009

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