Fabrication of different rare earth incorporated ZnCo2O4 matrix via chemical-mechanical hybrid mechanism and study their charge carrier dynamics by Motts VRH model

摘要

This work reports how microstructural and electrical property varies with different rare-earth (Nd, Sm, Gd, Dy and Y) incorporation in spinel structured ZnCo2O4 nano-cobaltite. These materials have been synthesized using a combination of both chemical and physical methods. Host spinel material was prepared through chemical co-precipitation method and mechanical milling was used to reinforce the rare earth oxides into the spinel structure. Structural, microstructural, elemental and optical characterization has been carried out using XRD, FTIR, FESEM, EDX and UV-Vis spectroscopy. XRD confirms the formation of the nanocrystalline materials. Different microstructural parameters like lattice parameters, microstrain, crystallite size and x-ray density have been estimated from Rietveld analysis, which shows particle size of the doped samples depends on size of the dopant rare earth. Positions of different bonds have been confirmed from FT-IR analysis. FESEM micrographs confirm particle dimensions of the agglomerated spherical grains are in good agreement with Rietveld output. Optical band gap increases with decreasing dopant radii from 3.48 eV to 3.99 eV. Impedance plots show highest conductivity achieved was 1.151 x 10(-3) Omega(-1)cm(-1) at 433 K for Yttrium doped ZnCo2O4 nano-composition with lowest activation energy of 0.34 eV. Temperature dependent frequency exponent explains small polaron hopping transaction. Impedance master curves obey time-temperature superposition principle. Motts VRH model applied to electrical properties to get an insight about electrical conduction mechanism of the prepared samples. (C) 2021 Elsevier B.V. All rights reserved.