Abstract
We report on the use of SEM and X-ray diffraction to characterize Zn‒Ni/TiO
2
and Hg‒Ni/TiO
2
composites. The ac conductivity was measured for these composites at 0.1 kHz to 3 MHz for the temperatures from 25 to 100 °C. Due to difference in ionic radius, we noticed a shifting in all diffraction peaks to higher theta degree in X-ray diffraction spectra for Hg‒Ni/TiO
2
compared to undoped TiO
2
, whereas no peak shift was observed in Zn‒Ni/TiO
2
. The transformation from anatase to rutile phase was observed after doping TiO
2
which means the prepared composites in this report would have high photocatalytic activity. Furthermore, reduction in the crystallite size was observed from 19.57 nm (undoped TiO
2
) to 14.36 nm (Ni/TiO
2
), whereas in the case of the bimetallic (Zn‒Ni and Hg‒Ni) doped TiO
2
, the crystallite size increased to 15.5 nm. The dielectric permittivity of ɛ` decreased with growing frequency and is considerably changed by doping with Ni, Zn‒Ni, and Hg‒Ni to TiO
2
. The observed increase in the ac conductivity with the increasing frequency was attributed to the hopping conduction mechanism for all samples. The activation energy is calculated and found in the range of 0.01 to 0.32 eV where their values depend on the applied frequency and the type of the additional metals to TiO
2
nanoparticles. Additionally, the UV–vis spectrometer was utilized to characterize the samples’ optical properties such as the reflectance, refractive index, and dispersion energy.