Ti4+ and Ge4+ ionic substitution in Cu-ferrite, electrical conductivity and thermoelectric power

Abstract Both the DC conductivity and the thermoelectric power of Cu 1+ x Ge x Fe 2−2 x O 4 and Cu 1+ x Ti x Fe 2−2 x O 4 ferrites, for 0⩽ x ⩽0.4, were measured in a wide range of temperature from RT up to 773 K. The measurements showed that the substitution of both tetravalent ions (Ge 4+ and Ti 4+ ) tend to convert Cu-ferrite from n- to p-type semiconductor. The results were analyzed on the basis of the small polaron model. The cation distribution for each system was proposed. The activation energy Δ E , Fermi energy E F , the density of charge carriers n or p and the carriers mobility μ were determined for both systems. In addition, an energy band schemes of Cu–Ge and Cu–Ti ferrites were schematically represented.