Investigation of the crystal structure, electronic and optical properties of Cr-doped BaTiO3 on the Ti site using first principles calculations

Abstract

In this work, we have investigated the effect of chromium (Cr) doping on the structural, electronic and optical properties of the cubic phase of BaTiO 3 using first-principles calculations. Applying the GGA + U approximation, the lattice parameters as well as the band gaps of the undoped and doped phase of BaTiO 3 are in fairly good agreement with the experimental data, confirming the validity of our model. Furthermore, the chemical bonding analysis underlines the ionic character of Ba–O bonds and the covalent nature of Ti–O and Cr–O bonds. Additionally, the investigation of the optical properties using the Hubbard U-potential correction provided good agreement with the experimental data in the broad energy ranges. We have also demonstrated that the substitution of chromium on the Ti site, through the calculation of both electronic and optical properties , leads to the appearance of defects close to the Fermi level , allowing the appearance of the asymmetry of the BaTi 1-x Cr x O 3 system. As a result, the calculated total magnetic moment is 1.6038 μ B , indicating that doping with Cr renders the BaTi 1-x Cr x O 3 system ferromagnetic. Therefore, this work demonstrates that Cr-doped BaTiO 3 could reasonably constitute a new class of perovskite materials for magneto-optoelectronic applications. • Geometry optimization is performed for pure and Cr-doped BaTiO 3 with a 2 × 2 × 1 supercell. • Calculated band gaps of pure and Cr-doped BaTiO 3 are in quite good agreement with the experimental data. • Chemical bonds suggest that the Ba–O bonds are ionic as well as the Ti–O and Cr–O bonds are mainly covalent. • Cr doping renders the BaCr x Ti 1-x O 3 system ferromagnetic and gives it a total magnetic moment of 1.6038 μ B . • Optical properties validate the electronic analysis performed for both pure and Cr-doped BaTiO 3 .