Structural and optoelectronic properties of (Sc/N) and (Y/N) co-doped TiO2 rutile: A DFT study

This manuscript investigates the structural, electronic, and optical properties of Ti_1-xA_xB_yO_2-y (A = Sc, Y, and B = N with x = 0.0625 and y = 0.03125). The study employs the FP-LAPW method within the Wien2k code, utilizing density functional theory (DFT). Exchange and correlation potentials are treated with the generalized gradient approximation (GGA) and Becke-Johnson modified by Tran-Blaha (TB-mBJ) approaches. The structural results for pure TiO₂ are in agreement with available data. Lattice parameters (a₀ and c) increase when TiO₂ is co-doped with Sc/N and Y/N, while compressibility modulus B decreases compared to pure TiO₂. All calculated formation energies are negative, indicating thermodynamic stability for the compounds.

The study of electronic properties shows that all of these compounds have a direct gap at the high-symmetry point Г. When Sc/N and Y/N are added, impurity energy levels form above the top of the valence band, reducing the gap energy. Analysis of the optical spectra reveals that both pure TiO₂ and TiO₂ co-doped with Sc/N and Y/N exhibit enhanced absorption in the ultraviolet, indicating that these compounds are suitable for use in UV photo catalysis.