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.