Insights into the Impact of Yttrium Doping at the Ba and Ti Sites of BaTiO3 on the Electronic Structures and Optical Properties: A First-Principles Study

We reported a systematic study of the effects of Y doping BaTiO₃ at Ba and Ti sites. We assessed the structural, electronic, and optical properties by employing first-principles calculations within the Tran-Blaha-modified Becke-Johnson (TB-mBJ) potential and generalized gradient approximation + U approaches. We calculated the lattice constants and bond lengths for pure and Y-doped BaTiO₃. We explored the consequences of electronic structure and optical property modification because of Y doping in BaTiO₃. Indeed, Y doping has led to various modifications in the electronic structures of BaTiO₃ by inducing a shift of the conduction band through lower energies for the Ba site and higher energies for the Ti site. It was found that Y doping, either at Ba or at Ti sites, strongly enhanced the BaTiO₃ dielectric constant properties. The transformation in bonding was explored via the charge density contours and Born effective charges. We used the state of art of polarization theory based on finite difference and Berry-phase approaches to investigate piezoelectricity. Y doping has increased the dielectric constants but canceled the piezoelectricity as they changed to metallic nature. We could look into the future for potential doping, preserving the semiconductor nature of BaTiO₃ and increasing the permittivity with large dielectric loss.