Comparative Study of Zr/Te Co-Doped MgTiO₃: Structural, Electronic, and Optical Properties with Potential Applications

¹ Engineering and Applied Physics Laboratory (EAPL), Superior School of Technology, Sultan Moulay Slimane University, Beni Mellal, Morocco
² The Moroccan Association of Sciences and Techniques for Sustainable Development, Beni Mellal 23000, Morocco
³ ERCI2A, FSTH, Abdelmalek Essaadi University, Tetouan, Morocco
⁴ SECIHTI-Faculty of Chemical Sciences and Engineering, The Autonomous University of the State of Morelos (UAEM), Morelos, Cuernavaca, 62209, Mexico

Abstract

This study investigates the structural, electronic, and optical properties of pristine and Zr/Te co-doped MgTiO₃ using first-principles calculations based on density functional theory (DFT). The calculations were performed within the full-potential linearized augmented plane wave (FP-LAPW) method implemented in the WIEN2k code. Structural optimization was carried out using the generalized gradient approximation (GGA), while the Tran–Blaha modified Becke–Johnson (TB-mBJ) potential was employed to obtain improved electronic and optical properties. The optimized lattice parameter of pristine MgTiO₃ was found to be a = 3.8427 Å. The calculated band gap of undoped MgTiO₃ is 2.93 eV, confirming its wide-band-gap semiconducting nature with predominant ultraviolet absorption. Upon Zr and Te co-doping, the band gap significantly decreases to 1.15 eV for Mg₈Ti₇Zr₁O₂₃Te₁ and further to 0.64 eV for Mg₈Ti₇Zr₁O₂₂Te₂ due to dopant-induced electronic states near the Fermi level. Electronic structure analysis reveals strong hybridization between Te-p, O-p, Ti-d, and Zr-d orbitals, leading to band gap narrowing and a transition toward a direct band gap character. Optical calculations based on the complex dielectric function show a pronounced red shift of the absorption edge from the ultraviolet to the visible region, accompanied by an increase in the static dielectric constant and optical conductivity at low photon energies. These results demonstrate that Zr/Te co-doping effectively tunes the electronic structure and enhances visible-light absorption in MgTiO₃, highlighting its potential for optoelectronic and energy-related applications.