Tailoring optical and dielectric properties of TiO₂ through mono- and co-doping with Ag and Sr

In this study, we applied a direct and incipient wetness impregnation technique to synthesize titanium dioxide (TiO2) doped with silver (Ag), strontium (Sr), and a combination of the two elements. The purpose was to further our understanding of doped TiO2 materials. The results of scanning electron microscopy (SEM) analysis showed that the agglomerated particles of the doped composites had smaller sizes than those of pure TiO2 . The incorporation of Ag-Sr bimetallic doping led to a more pronounced reduction in the particle size. The SEM images revealed no significant morphological alterations in the TiO2 , Ag/TiO2 , Sr/TiO2 , and Ag-Sr/TiO2 composites. We also examined the dielectric characteristics of composites within a range of temperature of 25 degrees C-120 degrees C and a range of frequency of 100 Hz to 0.3 MHz. The electrical conductivity and dielectric permittivity of TiO2 were enhanced as a result of doping. The optical characteristics of the composites indicated that the introduction of Ag, Sr, and Ag-Sr into TiO2 led to an increase in both their refractive index and Urbach energy. This led in turn to a progressive reduction in the energy band gap (E-g) from the Ag -doped samples to the Ag-Sr-doped samples, with the Sr -doped samples exhibiting an intermediate reduction in E-g. The findings of this study indicate that the introduction of Ag, Sr, and Ag-Sr into TiO2 enhanced its refractive index. Notably, the Ag-Sr/TiO2 composite exhibited the most significant increase in the refractive index of all the composites considered. This phenomenon can be attributed to the increased level of polarization and crystallinity of the compound. By contrast, the incorporation of Ag, Sr, and Ag-Sr into composite materials composed of TiO2 led to a reduction in the values of E-g, where this renders these materials suitable for various optical applications.