DIELECTRIC BEHAVIOR OF CU1-XTIXFE2O4 FERRITES

The ac conductivity, dielectric constant, dielectric loss, and dielectric loss tangent of mixed ferrites Cu1-xTixFe2O4 (where x = 0 to 0.7) are measured at various frequencies and different temperatures. At different temperatures, it was observed that the ac conductivity ($) over tilde sigma for f < 10(4) Hz at x < 0.4 is f independent, at x > 0.4 increases slowly with f and for f > 10(4) Hz ($) over tilde sigma increases strongly with f. The dielectric loss (epsilon'') decreases with increasing frequency much more rapid than the dielectric constant (epsilon'). The general trend for all compositions is that epsilon' and epsilon'' decrease with increasing frequency, and the average decrease rates are 77.5 and 98.9%, respectively. For x less than or equal to 0.4, the activation energy Delta E(($) over tilde sigma) is nearly constant (about 0.30 eV), but for x > 0.4, Delta E(($) over tilde sigma) increases rapidly with increasing composition x. For x less than or equal to 0.4, not noticeable change in dielectric values (epsilon' and epsilon'') was observed at room temperature and constant frequency 10(5) Hz, but tan delta decreases rapidly with increase of Ti4+ content.