Abstract
The lattice parameters, bond lengths, bond angles (octahedra tilt angles), Goldschmidt tolerance factor, density of states and electronic band structure of rare-earth scandates LnScO(3) (Ln = Eu, La, Nd, Pr, Sm and Tb) in orthorhombic structure have been investigated in the generalized gradient approximation (GGA) + U method with the on-site Coulomb interaction parameter U-eff varying from 1 to 10 eV. The lattice constants, octahedra tilt angles (except for (Eu,Tb)ScO3 compounds), mean Sc-O and Ln-O bond lengths increased almost linearly with effective U parameter values. However, the tolerance factor has decreased (except for (Eu,Tb)ScO3 compounds). Density of states and electronic band structure computations show that LnScO(3 )compounds are insulator materials and have direct electronic band gap. The electronic band gap of the compounds first increases and then decreases with increasing U-eff . (GGA) + U calculation shows a strong hybridization between Sc-3d and O-2p states. Rare-earth (Ln)-5d states contribute somewhat to this hybridization. The electronic charge distribution and (P)DOS calculation results show that the bonding behavior of LnScO(3) compound is a combination of covalent and ionic nature. Our results show that the structural and electronic properties are affected by the application of the Hubbard U term in GGA calculations and the computed lattice constants, bond distances and octahedra tilt angles deviate more from the experimental values. On the other hand, it was observed that the electronic band gap approached the experimental values at the optimal U-eff values determined for the compounds.
NSTL
Elsevier