Impact of hydrogenation on the structural, optical and dielectric properties of (Sb + Dy) co-doped TiO₂ nanoparticles

Abstract

TiO₂ oxide nanoparticles co-doped with Sb/Dy ions were synthesized by a hydrothermal precipitation method. Some amount of the synthesized co-doped sample was hydrogenated at ~550°C for 30 min. The samples were characterized by traditional methods: structural investigation by X-rays, an optical investigation by spectral diffuse reflectance and AC dielectric measurements. It was noticed that 3%-Sb/Dy co-doping induces growth of mixed (Anatase + rutile) TiO₂ phases. The different styles of doping of Sb⁵⁺ and Dy³⁺ ions into TiO₂ nanocrystallites can be utilized to produce core/shell construction for the creation of colossal permittivity (CP). Thus, the dielectric permittivity for Sb/Dy co-doped TiO₂ was found to be of order ~10³ at 1 kHz. The hydrogenation was found to reduce the CP by influencing the core/shell constructions as well as by the creation of a high density of itinerant electrons, which could be estimated by the optical measurements. This result is important from point of view of studying the influence of hydrogenation on the dielectric properties of nano-sized transparent conducting oxides. The created CP was explained, in the present work, within the framework of the core/shell model and doping mechanisms. Such important results will be useful for future work on using hydrogenation to support/reduce CP depending on the types of dopant ions.