Electroconductivity, thermoelectrical properties and ESR spectroscopy of copper chromite ceramic samples doped with magnesium
V.A. Kulbachinskii1,2,3,4, V.G. Kytin1,5, D.Yu. Kondratieva1, E.A. Konstantinova1, A.V. Pavlikov1, A.N. Grigoriev1, A.S. Mankevich1, and I.E. Korsakov1
1Lomonosov Moscow State University, 1 Leninskie Gory, Moscow 119991, Russia
2Moscow Institute of Physics and Technology, Dolgoprudnyi, 141700, Russia
3National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) 31 Kashirskoe Shosse, Moscow 115409, Russia
4NRC "Kurchatov Institute", Moscow 123182, Russia
5The All-Russia scientific research institute physicotechnical and radio engineering Measurements, Mendeleevo, the Moscow region, 141570, Russia
Received Octouber 11, 2018, published online December 20, 2018
The results of investigation of copper chromite ceramic samples doped with magnesium are presented. Samples have been synthesized by solid state method with a special procedure of initial mixture preparation. Such procedure provides a uniform distribution of magnesium in the range from 0,2% to 6%. The substitution of chromium by magnesium in crystal lattice was confirmed by Raman spectrum and ESR investigation. When content of Mg increases in the range from 0% to 6% the resistivity of samples decreases down to three orders of magnitude at room temperature. High values of thermopower were observed and have been shown that the main carriers are holes and the mechanism of a charged transfer is a hopping conductivity. The density of localized states participating in the hopping conductivity decreases when energy incases near the Fermi energy. The localization radius increases when Mg concentration increases.
Key words: copper chromite, electron paramagnetic resonance, hopping conductivity, thermoelectricity, ceramic.