Abstract
Samples of the type CuFe
2−
x
Cr
x
O
4 with
x = 0.0, 0.2, 0.4, 0.6 and 0.8 were prepared. Ac conductivity measurements were carried out at different frequencies up to 10
5 Hz and at various temperatures from room temperature up to about 550 K. The ac conductivity was measured using the phase detector technique (lock-in amplifier). The results showed that the conductivity increases with both temperature and frequency, and the activation energy in the paramagnetic region is higher than that in the ferrimagnetic region. At high temperatures the conductivity becomes frequency independent. We conclude that the conductivity in these ferrites consists of two kinds of conduction mechanisms.