Electronic Structure Calculations of A2Ti2O7 (A = Dy, Ho, and Y)

Ab initio calculations have been performed on titanate pyrochlores A(2)Ti(2)O(7) (A = Dy, Ho, and Y) to investigate their electronic structures. The generalized gradient approximation (GGA) + U formalism has been used to correct the strong onsite Coulomb repulsion between the localized 4f electrons. The effects of effective.. values on the structural and electronic properties of A(2)Ti(2)O(7) (A = Dy, Ho, and Y) have been discussed. It is shown that Dy2Ti2O7 and Ho2Ti2O7 exhibit different electronic structures from Y2Ti2O7. The strong interaction between Dy and Ho 4f electrons and O 2p orbitals may increase the covalency of < Dy-O > and < Ho-O > bonds and decrease their irradiation resistance.