Impact of metal doping on the physical characteristics of anatase titanium dioxide (TiO2) films

Abstract

This study focuses on the synthesis of anatase titanium dioxide (TiO₂) films doped with metals (Mg, Ni, and Sn) using the sol–gel dip coating technique. The main objective was to investigate the chemical, crystal, and morphological structure of the Mg-, Ni-, and Sn-doped TiO₂ films. The doping mechanism between the metals and the TiO₂ films was confirmed through Fourier-transform infrared (FTIR) spectroscopy, which revealed characteristic absorption bands associated with the doping process. Additionally, X-ray diffraction (XRD) patterns confirmed that all films maintained an anatase phase, indicating the preservation of the desired crystal structure. Furthermore, the introduction of Mg and Sn metals into the TiO₂ film resulted in a decrease in the crystallite size, reducing it from 53 to 16 nm and 24 nm, respectively. Conversely, the incorporation of Ni into the TiO₂ film increased the crystallite size to 72 nm. Moreover, the presence of these metals in the TiO₂ film contributed to a smoother film surface, thereby enhancing the hydrophilicity of the films. The optical bandgap of the TiO₂ films decreased with the introduction of Mg, Ni, and Sn, exhibiting values of 3.24 eV, 3.11 eV, and 3.15 eV, respectively, compared to the original value of 3.33 eV. Additionally, the electrical conductivity (σ-value) increased upon the introduction of Mg, Ni, and Sn, reaching values of 0.25 mS.cm⁻¹, 0.37 mS.cm⁻¹, and 2.5 mS.cm⁻¹, respectively. Overall, this work provides insights into the chemical, crystal, and morphological characteristics of Mg-, Ni-, and Sn-doped TiO₂ films.