First-principles investigation of mechanical and electronic properties of LaAg5 Laves phase under pressure

The effects of applied pressure on the structural, mechanical, and electronic properties of LaAg5 compound were investigated employing the first-principles method based on the density functional theory. The mechanical results demonstrated that bulk modulus, shear modulus and Young's modulus presented the linearly increasing dependences on the external pressure; the B/G and Poisson's ratio indicated that LaAg5 compound was a ductile material with central forces in interatomic under pressure from 0 to 40 GPa; the universal anisotropic index was performed to investigate the elastic anisotropic of LaAg5. Additionally, the pressure dependence of the density of states and Mulliken charge were also discussed. The bonding characterization in LaAg5 was composed of metallic, covalent and ionic. The metallic component was derived from free-electron transferring from Ag-s and Ag-d to Ag-p, and from La-s to La-d. The ionic component was due to the charge movement from La to Ag. The covalent was owing to Ag-p-La-d bonding hybridization and Ag-s-Ag-p in the Ag atomic chains. The covalent and ionic bonds were stronger under pressure but there was no significant change in metallic nature.

Graphical AbstractSchematic structure of LaAg5 with C14 structure (Yellow spheres representing two Ag atoms at 2a site locating lattice and six Ag atoms at 6h site inside the cell, gray spheres representing two silver atoms and two lanthanum atoms at 4f site, marked as fi (i=1, 2, 3, 4))Figure optionsDownload as PowerPoint slide