Electrical conductivity, thermoelectrical properties, and EPR spectroscopy of copper chromite ceramic samples doped with magnesium

The results of a study of copper chromite ceramic samples doped with magnesium are presented. The samples were synthesized according to the solid-phase method using a special procedure for preparing the initial mixture, which ensures a uniform distribution of magnesium with its content from 0.2 to 6%. The substitution of chromium for magnesium in the crystal lattice is confirmed by Raman scattering of light and EPR spectra. As the magnesium content increases from 0 to 6 at.%, the resistivity of the synthesized samples decreases by more than 3 orders of magnitude at room temperature. High thermopower values were obtained, and it was shown that the main charge carriers are holes, and the predominant mechanism of hole transport in doped samples is hopping transfer over localized states, whose density decreases with an increase in energy near the Fermi energy. It is shown that the localization radius increases with an increase in magnesium content.