Y/Pd co-doping-induced modifications in TiO2 nanoparticles: structural, optical, and electrical perspectives

Nanoparticles (NPs) of TiO2 co-doped with yttrium (Y) and palladium (Pd) ions were synthesized by a hydrothermal decomposition technique. The relative molar concentration of Pd dopant ions in the samples were 1 at%, 2 at%, and 3 at%, while that of Y ions was 3 at% in each sample. The synthesized samples were characterized by traditional experimental methods. The crystalline structures were studied by X-ray diffraction (XRD) and their optical properties were investigated by diffuse optical reflection spectroscopy (DRS). The doping basis mechanism was used to synthesize the dielectric crystalline solid solution (SS) medium, which behaves as a core/shell-like electronic structure to generate giant permittivity (GP). The XRD peaks were indexed according to the Anatase structures of TiO2. The direct band gap energy (Eg) of the synthesized undoped TiO2 nanopowder was 3.26 eV, which was reduced to 3.02, 2.81, and 2.48 eV by doping with 1% Pd for sample S1, 2% Pd for S2, and 3% Pd for S3, in addition to the 3% Y dopant in each sample, respectively. The nano-sized pressed powder samples exhibited almost giant permittivity at an RT of ~1.77 × 103, ~5.79 × 102, and ~4.91 × 102 for S1, S2, and S3, respectively, while it was 160 for undoped TiO2. The enhancement of TiO2 permittivity was attributed to the planned formation of equivalent core/shell-like structures. Thus, the purpose of the present co-doping was successfully achieved.