CHARGE-TRANSPORT AND CONDUCTION MECHANISM OF COPPER SUBSTITUTED MAGNESIUM ALUMINUM FERRITES

Electrical conductivity (sigma) and thermopower (S) studies of polycry stalline copper substituted magnesium aluminium ferrites of different composition were investigated in the temperature range 300-800 K. Plot s of log (sigmaT) versus 10(3)/TU are almost linear and show a clear t ransition near the Curie temperature. On the basis of the sign of Seeb eck coefficient, all the samples under investigation have been classif ies as n-type semiconductors. The temperature variation of Seebeck coe fficient curves also exhibited a well defined magnetic transition at t he Curie temperature. Using the temperature variation of charge carrie r mobility a conduction mechanism in these ferrites is suggested.