Influence of Merge CoDoping of Bi/Ni ions on the Structural, Optical, and Colossal Dielectric Properties of TCO Anatase TiO2 Nanoparticles: Impact of Post-annealing in Hydrogen Gas Atmosphere

A hydrothermal precipitation technique was used to synthesize TiO 2 oxide nanoparticles doped with Bi/Ni ions. X-ray diffraction, diffuse reflection spectroscopy, and ac-dielectric measurements were used to investigate the mechanical, optical, and dielectric properties of the synthesized NPs powder. Using Bi/Ni ionic codoping, TiO 2 NCs were constructed as core/shell nanostructures. A key contribution of this work was the creation of colossal permittivity (CP). Thus, the dielectric measurements show CP of magnitude ~ 5 × 10 6 at room temperature and frequency of 1 kHz that was reduced to 2.7 × 10 5 by the hydrogenation of the sample, which are much more than that of pristine TiO 2 . Within the framework of the core/shell model and doping mechanisms, CP was explained in detail. Additionally, hydrogenation was explained as a reduction in CP by increasing itinerant electron concentrations as a result of the strong catalyst power of dopant Ni 2+ ions dissociating adsorbed hydrogen.