Abstract
In this work, the effect of cobalt ions on the structural and dielectric properties of La0.8K0.2MnO3 manganite prepared via the simplest sol-gel route is studies. The X-ray diffractions analyses reveal that our perovskites, with the general formula La0.8K0.2Mn1-xCoxO3 (x = 0, 0.03, 0.06), crystallized by a rhombohedral structure with R3 over bar c space group. Rietveld refinement indicates that each octahedron (Mn, Co)O-6 has little deformation and that the theta((Mn, Co)-O-(Mn, Co)) bond angles decrease with increasing Co content. From the conductance measurements, it is noticed that the substitution into the Mn site of the LaKMnO3 material by cobalt increases its conductivity. However, the electrical conductance of our perovskites is well described by the universal Jonscher's law. It is deduced that the conduction process of the present structures occurs between neighboring sites. In addition, the dielectric constant and loss tangent can be explicated based on Maxwell-Wagner polarization. Finally, the Nyquist diagram is fitted by an adequate equivalents circuit, the obtained results depict a non-Debye relaxation process in these materials.