Synthesis, characterization, and dielectricity performance of bulk pristine Fe3+ and Li+ Co-substituted wurtzite ZnO

High dielectric constant materials are of technological importance as they lead to the miniaturization of electronic devices. The permittivity of a material determines the relative speed that an electrical signal can travel in that material. The dielectric properties of pure ZnO are developed due to the defects of zinc excess at the interstitial position and the lack of oxidation. Fe and Li co-doping in ZnO are envisaged here to develop high dielectric materials by converting the material into a p-type semiconductor without creating stoichiometric oxygen defects in the lattice and making it robust against the oxidizing atmosphere. The formation of single-phase Fe and Fe/Li co-doped wurtzite ZnO samples is confirmed by X-ray diffraction analysis. The Fe and Fe/Li doping depresses the concentration of the intrinsic donor and impedes the conduction mechanism resulting in the highest dielectric constant (ɛr′) equivalent to 612 and 90,000 are found for bulk pristine Zn0.9Fe0.1O and Zn0.8Li0.1Fe0.1O at 400oC with 1000 ​Hz applied frequency. Also with an increase in frequency, the dielectric constant and dielectric loss are found to decrease. This behavior is attributed to different hopping mechanisms and defects formed during synthesis. Bulk Pristine Zn0.8Li0.1Fe0.1O shows high-k Dielectric behavior due to the substitution of multivalent cations resulting in net polarization in the lattice. [Display omitted] •Successfully demonstrated the synthesis of single-phase Fe-doped ZnO and Fe/Li co-doped ZnO. In this work, bulk pristine Zn1-xFexO, and Zn1-2xLixFexO (x ​= ​0.05 and 0.10) ceramic samples were prepared by the sol-gel method.•The complex impedance spectroscopic study of Fe-doped and Fe/Li co-doped ZnO shows a high dielectric constant and low dielectric loss at high temperatures and high frequency compared to ZnO.•The Fe and Fe/Li doping depresses the concentration of the intrinsic donor and impedes the conduction mechanism resulting in the highest dielectric constant (ɛr′) equivalent to 612 for Zn0.9Fe0.1O and 90,000 for Zn0.8Li0.1Fe0.1O at 400oC with 1000 ​Hz applied frequency.•The presence of multiple charge centers or different oxidation state cations in the lattice resulted in differentiative iconicity or polarization in M ​− ​O bonds generating a high net dipole moment in the lattice that is responsible for the high k dielectricity of the material at elevated temperatures.