Effect of Si substitution on structural, electronic and optical properties of YNi4Si-type DyNi5−xSix (x=0, 1, 2) compounds

• Calculated DOS revels that Ni-3d states are dominated below Fermi level (EF).
• Spin down Dy-4f states show significant contribution to DOS above EF.
• Nickel moments decrease rapidly with substitution of silicon for nickel (DyNi4Si).
• Most significant peak is found around 7eV in optical conductivity.
• Nickel moments decrease rapidly with substitution of silicon for nickel (DyNi4Si).
• Peak indicates the possibility of transitions from Ni-3d states to empty spin down Dy-4f states.

We employed first principle calculations for investigation of structural, electronic and optical properties of YNi4Si-type DyNi5−xSix (x=0, 1, 2) compounds. These properties are studied first time on YNi4Si-type DyNi5−xSix compounds. The exchange and correlation potential is treated by the Coulomb corrected local spin density approximation (LSDA+U) method for better accounting of the correlation between the 4f electrons. The optimized lattice constants and internal cell parameters are in agreement with the available data. Self consistence band structure calculations show that Ni-3d states remains in valance band and dominant below the EF, while Dy-5d and 4f states mainly contributes above Fermi Energy (EF) in DyNi5−xSix (x=0, 1, 2) compounds. We also find that when silicon for nickel substitution takes place (DyNi4Si), there is a gradual hybridization of Ni-3d and Si-3p states results, nickel moments decrease rapidly in agreement with the experiment. Optical spectra shows the main absorption peak around 4 eV depends on the substituent concentration and could be due to transition from hybridized band (Ni-3d and Si-3p), below EF to free Dy-4d states. Frequency-dependent refractive index, n(ω), and the extinction coefficient, k(ω), of DyNi5−xSix (x=0, 1, 2) are also calculated for the radiation up to 14 eV.