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

Abstract We employed first principle calculations for investigation of structural, electronic and optical properties of YNi 4 Si-type DyNi 5− x Si x ( x =0, 1, 2) compounds. These properties are studied first time on YNi 4 Si-type DyNi 5− x Si x 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 4 f electrons. The optimized lattice constants and internal cell parameters are in agreement with the available data. Self consistence band structure calculations show that Ni-3 d states remains in valance band and dominant below the E F , while Dy-5 d and 4 f states mainly contributes above Fermi Energy ( E F ) in DyNi 5− x Si x ( x =0, 1, 2) compounds. We also find that when silicon for nickel substitution takes place (DyNi 4 Si), there is a gradual hybridization of Ni-3 d and Si-3 p 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-3 d and Si-3 p ), below E F to free Dy-4 d states. Frequency-dependent refractive index, n ( ω ), and the extinction coefficient, k ( ω ), of DyNi 5− x Si x ( x =0, 1, 2) are also calculated for the radiation up to 14 eV.