Structural and elastic properties of La2Mg17 from first-principles calculations

Structural and elastic properties of La2Mg17 with layer structure have been investigated within framework of the density functional theory. Different from the general layer-structured materials, the obtained c/a is less than unity. The calculated elastic constants C33 is larger than C11, being novel in comparison with other alloys with layer structure. The calculated bulk, shear and Young's modulus of La2Mg17 are higher than other Mg–La alloys with higher La content, implying the stronger covalent bonding. Moreover, the elastic isotropies of La2Mg17 are more excellent. The electronic structure within basal plane is highly symmetric, and the electronic interaction within basal plane is slightly weaker than one between basal planes, which reveal the underlying mechanism for the structural and elastic properties of La2Mg17. - Graphical abstract: The crystal structure (a) and the atomic positions for (b) (0 0 0 2), (c) (0 0 0 4) and (d) (1 2¯ 1 0) plane of La2Mg17. Display Omitted - Highlights: • The c/a of La2Mg17 is anomalously less than unity. • It is novel that for La2Mg17 the elastic constants C33 is larger than C11. • The elastic modulus of La2Mg17 is higher than other Mg–La alloys. • The elastic isotropy of La2Mg17 is excellent. • The electronic structure within basal plane is highly symmetric