DFT investigation on the rare earth effects of Mg8Si3RE (RE=Sc, La, Ce, Yb) compounds

Abstract The mechanical and electronic properties of β phase (Mg2Si) doping with rare earth (RE) atoms (Sc, La, Ce, Yb) were investigated by first-principles based on density functional theory. The results showed that both Mg8Si3RE and Mg7Si4RE can exist stably by doping from the analysis of formation energy and cohesive energy. We found that RE atoms doping into the Mg2Si lattice tends to occupy Mg position preferentially. Doping Yb which has the largest Hv can strength the stiffness of compound, meanwhile, Mg7Si4Ce has the smallest stiffness. The ductility of Mg2Si increases after doping with La (Ce). Doping RE atoms cause strong orbital hybridization between Al and RE, so the bonding strength and stability of Mg2Si can be significantly changed.