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Effects of vacancies on phonon entropy of B2 FeAl

Publication ,  Journal Article
Lucas, MS; Delaire, O; Winterrose, ML; Swan-Wood, T; Kresch, M; Halevy, I; Fultz, B; Hu, J; Lerche, M; Hu, MY; Somayazulu, M
Published in: Physical Review B - Condensed Matter and Materials Physics
December 21, 2009

The phonon density of states (DOS) and phonon entropy of B2 FeAl were determined as functions of the Fe site vacancy concentration using several scattering techniques and were computed from first principles. Measurements at elevated temperature and pressure were performed to explore volume effects, test the usefulness of the quasiharmonic (QH) approximation, and provide comparison for the first-principles calculations. The average temperature and pressure dependencies of phonons were consistent with the QH model. The decrease in specific volume associated with the introduction of vacancies causes a stiffening of the DOS that was captured well with the experimentally determined Grüneisen parameter. Features associated with vacancies in the DOS are not well explained by this model, however, especially in the gap between the acoustic and optic branches. First-principles calculations indicated that these modes are primarily associated with vibrations of Al atoms in the first-nearest-neighbor shell of the vacancy, with some vibration amplitude also involving the second-nearest-neighbor Fe atoms. At the vacancy concentrations of study, the phonon entropy of vacancy formation was found to be approximately -1.7 kB /atom, about half as large and of opposite sign as the configurational entropy of vacancy formation. © 2009 The American Physical Society.

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Published In

Physical Review B - Condensed Matter and Materials Physics

DOI

EISSN

1550-235X

ISSN

1098-0121

Publication Date

December 21, 2009

Volume

80

Issue

21

Related Subject Headings

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

Citation

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Lucas, M. S., Delaire, O., Winterrose, M. L., Swan-Wood, T., Kresch, M., Halevy, I., … Somayazulu, M. (2009). Effects of vacancies on phonon entropy of B2 FeAl. Physical Review B - Condensed Matter and Materials Physics, 80(21). https://doi.org/10.1103/PhysRevB.80.214303
Lucas, M. S., O. Delaire, M. L. Winterrose, T. Swan-Wood, M. Kresch, I. Halevy, B. Fultz, et al. “Effects of vacancies on phonon entropy of B2 FeAl.” Physical Review B - Condensed Matter and Materials Physics 80, no. 21 (December 21, 2009). https://doi.org/10.1103/PhysRevB.80.214303.
Lucas MS, Delaire O, Winterrose ML, Swan-Wood T, Kresch M, Halevy I, et al. Effects of vacancies on phonon entropy of B2 FeAl. Physical Review B - Condensed Matter and Materials Physics. 2009 Dec 21;80(21).
Lucas, M. S., et al. “Effects of vacancies on phonon entropy of B2 FeAl.” Physical Review B - Condensed Matter and Materials Physics, vol. 80, no. 21, Dec. 2009. Scopus, doi:10.1103/PhysRevB.80.214303.
Lucas MS, Delaire O, Winterrose ML, Swan-Wood T, Kresch M, Halevy I, Fultz B, Hu J, Lerche M, Hu MY, Somayazulu M. Effects of vacancies on phonon entropy of B2 FeAl. Physical Review B - Condensed Matter and Materials Physics. 2009 Dec 21;80(21).

Published In

Physical Review B - Condensed Matter and Materials Physics

DOI

EISSN

1550-235X

ISSN

1098-0121

Publication Date

December 21, 2009

Volume

80

Issue

21

Related Subject Headings

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