ELECTRICAL-PROPERTIES OF ZR4-FERRITE( SUBSTITUTED CU)

Electrical resistivity and thermoelectric power measurements are made on the system CU1+x2+Zrx4+Fe2-2x3+O42- with x=0.05, 0.1, 0.15, 0.2 and 0.3. Temperature variation of the resistivity exhibits two breaks. Th ese breaks are associated with a change in activation energy. In the l ow temperature range, the conduction is extrinsic while it is intrinsi c at high temperatures. Variation of the Seebeck coefficient from room temperature up to 800 K reveals n-type conductivity for the compositi on with x=0.05, while for the remaining samples, it is p-type of lower temperatures and n-type at higher temperatures. Fermi energies E(F)(0 ) have been calculated and these values agree with the activation ener gies calculated from resistivity studies in the low temperature range, suggesting impurity conduction in this region. The mobility increases with the increase of temperature. The activation energy in the high t emperature region consists of two parts, one part associated with the generation of electrons and the other part associated with the hopping of polarons between equivalent sites.