Thermodynamic and mechanical stabilities of tantalum nitride

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 orthorhom...

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Bibliographic Details
Published in:Physical review letters 2009-10, Vol.103 (18), p.185501-185501, Article 185501
Main Authors: Jiang, Chao, Lin, Zhijun, Zhao, Yusheng
Format: Article
Language:English
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Summary: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.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.103.185501