Dielectric and magnetic permeability behavior of BaCo2-xNixFe16O27W-type hexaferrites

A series of polycrystalline W-type hexagonal ferrite samples with the compo sition BaCo2-xNixFe16 O-27 were prepared by the well-known double-sintering ceramic process. The dielectric constant epsilon', dielectric loss tangent tan delta and initial magnetic permeability mu(0) was investigated as a fu nction of frequency, temperature and composition. It was found that both di electric constant epsilon' and dielectric loss tangent tan delta increase w ith increasing nickel ions substitution. The behavior of the dielectric con stant with frequency and temperature was explained on the basis of the hopp ing conduction mechanism and Rezlescu model. The anomaly of the initial mag netic permeability with temperature was attributed to the behavior of the m agnetocrystalline anisotropy constant with temperature and composition. (C) 1999 Elsevier Science B.V. All rights reserved.