Elsevier

Computational Materials Science

Volume 128, 15 February 2017, Pages 337-342
Computational Materials Science

Metastable phases, phase transformation and properties of AlAs based on first-principle study

(Click DOI to download directly)

Abstract

By utilizing an evolutionary methodology on crystal structure search, we propose three new metastable phases for aluminum arsenide (AlAs) as follows: (1) a P6422 symmetric structure (hP6-AlAs), (2) a C222 symmetric structure (oC12-AlAs), and (3) a I4¯3d symmetric structure (cI24-AlAs). By controlling the unloading pressure rate, oC12-, hP6-, and cI24-AlAs may be acquired through quenching NiAs-AlAs. The elastic constants and phonon dispersion spectra are calculated to certify the mechanical and dynamic stabilities of three newly discovered phases. On the basis of first-principle study, we explore phase transformations under pressure for several AlAs polymorphs. The calculation of mechanical properties illustrates that oC12-, and hP6-AlAs possess similar hardness levels, which are higher than that of cI24-AlAs. Meanwhile, oC12-, and hP6-AlAs hold similar shear anisotropic factors, which are smaller than that of cI24-AlAs. Electronic band structure calculation reveals that at zero pressure, oC12-, and hP6-AlAs possess indirect band gaps of 0.468 eV and 1.356 eV, respectively. cI24-AlAs is a direct semiconductor with a gap value 1.761 eV.

Graphical abstract

Utilizing CALYPSO, three new metastable phases for AlAs are proposed: (1) a P6422 symmetric structure (hP6-AlAs), (2) a C222 symmetric structure (oC12-AlAs), and (3) a I4¯3d symmetric structure (cI24-AlAs). With controlling unloading pressure rate, oC12-, hP6-, and cI24-AlAs may be acquired by quenching NiAs- or cmcm-AlAs. oC12-, and hP6-AlAs possess similar hardness, which is higher than that of cI24-AlAs. Meanwhile, oC12-, and hP6-AlAs hold similar shear anisotropic factors, which are smaller than that of cI24-AlAs. Electronic band structure calculation reveals that at zero pressure, oC12-AlAs and hP6-AlAs possess indirect band gaps of 0.468 eV and 1.356 eV, respectively. cI24-AlAs is a direct semiconductor with a gap value 1.761 eV.

Keywords

Aluminum arsenide
Phase transformation
Mechanical property
Electronic property
First-principle
View full text