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Nearly metastable rhombohedral phases of bcc metals

Publication ,  Journal Article
Mehl, MJ; Finkenstadt, D
Published in: Physical Review B - Condensed Matter and Materials Physics
February 14, 2008

The energy E(c/a) for a bcc element stretched along its [001] axis (the Bain path) has a minimum at c/a=1, a maximum at c/a=2, and an elastically unstable local minimum at c/a>2. An alternative path connecting the bcc and fcc structures is the rhombohedral lattice. The primitive lattice has R 3̄ m symmetry, with the angle α changing from 109.4° (bcc), to 90° (simple cubic), to 60 ° (fcc). We study this path for the non-magnetic bcc transition metals (V, Nb, Mo, Ta, and W) using both all-electron linearized augmented plane wave and projector augmented wave VASP codes. Except for Ta, the energy E(α) has a local maximum at α=60°, with local minima near 55° and 70°, the latter having lower energy, suggesting the possibility of a metastable rhombohedral state for these materials. We first examine the elastic stability of the 70° minimum structure, and determine that only W is elastically stable in this structure, with the smallest eigenvalue of the elastic tensor at 4 GPa. We then consider the possibility that tungsten is actually metastable in this structure by looking at its vibrational and third-order elastic stability. © 2008 U.S. Government.

Duke Scholars

Published In

Physical Review B - Condensed Matter and Materials Physics

DOI

EISSN

1550-235X

ISSN

1098-0121

Publication Date

February 14, 2008

Volume

77

Issue

5

Related Subject Headings

  • Fluids & Plasmas
  • 09 Engineering
  • 03 Chemical Sciences
  • 02 Physical Sciences
 

Citation

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Mehl, M. J., & Finkenstadt, D. (2008). Nearly metastable rhombohedral phases of bcc metals. Physical Review B - Condensed Matter and Materials Physics, 77(5). https://doi.org/10.1103/PhysRevB.77.052102
Mehl, M. J., and D. Finkenstadt. “Nearly metastable rhombohedral phases of bcc metals.” Physical Review B - Condensed Matter and Materials Physics 77, no. 5 (February 14, 2008). https://doi.org/10.1103/PhysRevB.77.052102.
Mehl MJ, Finkenstadt D. Nearly metastable rhombohedral phases of bcc metals. Physical Review B - Condensed Matter and Materials Physics. 2008 Feb 14;77(5).
Mehl, M. J., and D. Finkenstadt. “Nearly metastable rhombohedral phases of bcc metals.” Physical Review B - Condensed Matter and Materials Physics, vol. 77, no. 5, Feb. 2008. Scopus, doi:10.1103/PhysRevB.77.052102.
Mehl MJ, Finkenstadt D. Nearly metastable rhombohedral phases of bcc metals. Physical Review B - Condensed Matter and Materials Physics. 2008 Feb 14;77(5).

Published In

Physical Review B - Condensed Matter and Materials Physics

DOI

EISSN

1550-235X

ISSN

1098-0121

Publication Date

February 14, 2008

Volume

77

Issue

5

Related Subject Headings

  • Fluids & Plasmas
  • 09 Engineering
  • 03 Chemical Sciences
  • 02 Physical Sciences