CONDUCTION MECHANISM IN SN4+ SUBSTITUTED COPPER FERRITE

Thermoelectric power (alpha) and electrical resistivity (rho) are repo rted for the system Cu1+xSnxFe2-2xO4 (where x = 0.05, 0.1, 0.15, 0.2 a nd 0.3) from room temperature to 800 K. The compositions with x = 0.05 and 0.2 exhibit n-type conduction while the compositions with x = 0.1 and 0.15 show p- to n-type conduction change after 423 K. The conduct ion at low temperature (i.e. <400 K) is due to impurities, while at hi gher temperature (i.e. >400 K), it is due to polaron. Hopping conducti on phenomenon for the present system has been explained on the basis o f localized model of electrons. Additional localization may arise due to Sn4+ + Fe2+ stable pairs at B-site and Cu1+ + Fe3+ pair at A-site.