Electrical Conduction in CoFe2-xTixO₄ and Co1-xFe2+xO₄ Single Crystals

The a. c. resistivity in the range of 100 Hz to 100 MHz and thermoelectric power were measured for CoFe 2- x Ti x O 4 and Co 1- x Fe 2+ x O 4 single crystals ( x =0.06, 0.10. and 0.14) in the temperature range between 78 and 300 K. Electrical properties are quite similar for both systems. The concentration of electron carriers increases exponentially with increasing temperature. Its activation energy decreases with increasing ferrous ion contents ( x ). The mobility takes the value of 2×10 -2 cm 2 /V.sec at 300 K and decreases with decreasing temperature. Its activation energy is about 0.05 eV and dose not depend on x . The electrical conduction for both systems is satisfactorily explained in terms of the small-polaron hopping model.