Open Access

ARTICLE

Lattice Dynamics and Second and Third Order Elastic Constants of Iron at Elevated Pressures

by Hieu H. Pham¹, Tahir Ça ˇgın¹

1 Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station,TX, U.S.A.

Computers, Materials & Continua 2010, 16(2), 175-194. https://doi.org/10.3970/cmc.2010.016.175

Abstract

We analyze the lattice dynamics of Fe in different crystal phases (bcc, fcc and hcp) by using density-functional theory. The study on equations of states indicates that bcc Fe is more stable than fcc and hcp Fe at low pressures. However, dynamical instabilities in lattice vibrations of bcc Fe predict a phase transformation from bcc to hcp at higher pressures. We reported a complete set of second-order and third-order elastic constants of Fe in these three phases. We observed a linear variation in the values of second order elastic constant as a function of increased pressures. The phonon spectra were also analyzed to understand the stability of Fe in different phases.

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