First-principles study of structure, mechanical and optical properties of La- and Sc-doped Y2O3

The electronic, mechanical and optical properties of La-and Sc-doped Y2O3 were investigated using first-principles calculations. Two doping sites of Sc and La in Y2O3 were modeled. The calculated values of the energy of formation show that the most energetically favorable site for a La atom in Y2O3 is a d-site Y atom, while for Sc a b-site Y atom is the more stable position. The calculated band gap shows a slight decrease with increasing La or Sc concentration. The calculated results for the mechanical and optical properties of Y2–xRxO3 (R = Sc or La, 0 < x ≤ 0.1875) show that La- or Sc-doped Y2O3 would have enhanced strength, and thus an ability of resisting external shocks, and increased hardness and mechanical toughness. These improved mechanical properties are achieved without sacrificing the optical properties of the doped compounds. So the doping of La or Sc in Y2O3 is permissible in the preparation of Y2O3 transparent ceramics, of course, doping of La or Sc will benefit the sintering of transparent ceramics.