TY - JOUR

T1 - Landau free energy for a bcc-hcp reconstructive phase transformation

AU - Sanati, Mahdi

AU - Saxena, A.

AU - Lookman, T.

AU - Albers, R. C.

N1 - Copyright:
Copyright 2020 Elsevier B.V., All rights reserved.

PY - 2001

Y1 - 2001

N2 - We study the bcc-hcp phase transition in Ti and Zr with the use of first-principles calculations. We have determined the complete energy surface from the bcc to hcp structure. The results are used to find an appropriate Landau free energy density for describing this transformation. The proposed Landau free energy density has two relevant order parameters: shear and shuffle. Through first-principles calculations, we show that the bcc structure is unstable with respect to the shuffle of atoms (TA1 N-point phonon) rather than the shear. Therefore, we reduce the two order parameter Landau free energy to an effective one order parameter (shuffle) potential, which is a reasonable approximation. In general, the effective Landau free energy is a triple-well potential. From the phonon dispersion data and the change in entropy at the transition temperature we find the free energy coefficients for Ti and Zr.

AB - We study the bcc-hcp phase transition in Ti and Zr with the use of first-principles calculations. We have determined the complete energy surface from the bcc to hcp structure. The results are used to find an appropriate Landau free energy density for describing this transformation. The proposed Landau free energy density has two relevant order parameters: shear and shuffle. Through first-principles calculations, we show that the bcc structure is unstable with respect to the shuffle of atoms (TA1 N-point phonon) rather than the shear. Therefore, we reduce the two order parameter Landau free energy to an effective one order parameter (shuffle) potential, which is a reasonable approximation. In general, the effective Landau free energy is a triple-well potential. From the phonon dispersion data and the change in entropy at the transition temperature we find the free energy coefficients for Ti and Zr.

UR - http://www.scopus.com/inward/record.url?scp=0034909614&partnerID=8YFLogxK

U2 - 10.1103/physrevb.63.224114

DO - 10.1103/physrevb.63.224114

M3 - Article

AN - SCOPUS:0034909614

VL - 63

SP - 2241141

EP - 2241147

JO - Physical Review B - Condensed Matter and Materials Physics

JF - Physical Review B - Condensed Matter and Materials Physics

SN - 1098-0121

IS - 22

M1 - 224114

ER -