Electronic and phonon properties of the full-Heusler alloys [X.sub.2]YAl : a density functional theory study

• Published in: Journal of materials science Vol. 49; no. 12; pp. 4180 - 4190
• Main Authors: Arikan, N, Iyigor, A, Candan, A, Ugur, S, Charifi, Z, Baaziz, H, Ugur, G
• Format: Journal Article
• Language: English
• Published: Springer 15.06.2014
• Subjects: Alloys; Analysis; Degassing of metals; Metals; Specialty metals industry; Specific gravity
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-014-8113-7

First-principle calculations have been carried out on the structural, electronic, elastic, and phonon properties of the full-Heusler alloys [X.sub.2]YAl (X = Co, Fe and Y = Cr, Sc). The calculations predict that the [Fe.sub.2]CrAl and [Co.sub.2]CrAl are half-metallic ferromagnets at the equilibrium lattice constant with a minority-spin energy gap of 0.2912 and 0.668 eV, respectively. [Fe.sub.2]ScAl exhibit a gap in the majority density of states, with a few states at the Fermi level and about 0.217 states [eV.sup.-1], unlike the other Heusler compounds; due to this, it is considered a false half metal, and [Co.sub.2]ScAl is considered a non-magnetic compound. The elastic constants were derived from the slopes of the acoustic branches in the phonon-dispersion curve. The calculated lattice constants, bulk modulus, and first-order pressure derivative of the bulk modulus are reported for the L21 structure and compared with previous values. Phonon-dispersion curves were obtained using the first-principle linear-response approach of the density-functional perturbation theory. The specific heat capacity at a constant volume [C.sub.V] of [X.sub.2]YAl (X = Co, Fe and Y = Cr, Sc) alloys is calculated and discussed.