Dielectric and AC conductivity for BaCo2-xCuxFe16O27 ferrites

A series of W-type hexaferrite samples with composition BaCo2-xCuxFe16O27 w ith x = 0.4, 0.6, 0.8, 1 and 1.2 was prepared by the standard ceramic techn ique. AC conductivity measurements were carried out at different frequencie s (10(2) - 10(5) Hz) and at different temperatures. The dielectric constant epsilon(r) and the dielectric loss tangent tan delta were measured in the same range of temperatures and frequencies. The measurements were carried o ut by using the phase detector technique. The results showed that the condu ctivity increases with both temperature and frequency and becomes frequency independent at high temperatures. The dielectric constant increases with i ncreasing temperature and gives abnormal behavior with frequency, where rel axation peaks were observed at certain frequencies. The peaks shift to high er frequency with increasing temperature. The abnormal behavior was explain ed by the presence of two types of charge carriers. (C) 2000 Elsevier Scien ce B.V. All rights reserved.