Metal and Nonmetal Ion Doping Effect on the Dielectric Relaxation of TiO2 Electrodes

Titanium dioxide (TiO2) is a highly stable, photosensitive, and nontoxic metal oxide. The physical and chemical properties of TiO2 electrodes have been explored extensively for the last few decades. However, a detailed and comparative study of the dielectric relaxation and carrier kinetics with the dopants is still lacking. Herein, the crystallinity of TiO2 electrodes decreased with the dopants is reported. The doping of copper (Cu) in TiO2 reduces its bandgap to 2.98 eV from 3.22 eV. The improved charge carrier conduction at high frequencies (omega = 10(3)-10(6) radians s(-1)) with the doping is noticed. The charge transfer resistance (R-ct) for the electrons is minimum for Cu-TiO2 (R-ct = 34.11 omega) and Cu, Zn, and N-TiO2 (R-ct = 27.44 omega) compared to pristine and Cu and Zn-TiO2. Further, the high electrical permittivity is associated with the polar nature of electrodes. The correlation analysis of impedance and modulus spectroscopy data provides a prodigious picture of the charge carrier relaxation and conduction mechanism. A shift in the dielectric relaxation process from Debye type to non-Debye type is observed after doping due to defect-mediated fast relaxation of polarization.