Features of hole transport and density of localized states in CuCr1-xMgxO2 and CuCr1–yMgyO2/(MgCr2O4)x–y polycrystalline ceramics

Abstract

Magnesium doped polycrystalline ceramic samples of cooper chromite (I) with 0.6-4.0 at % Mg content have been synthesized. Phase composition of ceramics has been investigated by X-ray diffraction. Temperature dependencies of electrical resistivity and Seebeck coefficient have been measured by four probe method and analyzed in frame of variable range hopping conductivity. The density of localized electronic states and characteristic energy of its variation near Fermi energy have been estimated. It was obtained that the density of localized states at Fermi energy increases with an increase of Mg content, while characteristic energy of variation of localized state density near Fermi energy decreases. Obtained results show that relatively large values of Seebeck coefficient in Mg doped copper chromite (I) can be understood within variable range hopping transport of holes with rapidly increasing density toward valence band maximum