Abstract
Y-type hexagonal ferrite samples with the composition Sr2Cu2-xMnxFe12O22 (x = 0.0, 0.4, 0.8, 1.2, 1.6 and 2.0), have been prepared by the ceramic method. The X-ray diffraction patterns at room temperature show that the prepared samples have a single phase and the effect of composition on the unit cell parameters, density and porosity has been studied. The variation of the initial magnetic permeability (mu(i)) with temperature for all the investigated samples in the temperature range (300-780 K) has shown three regions of behaviour which has been explained on the basis of the proportionality mu(i) proportional to M-s(2)/K-eff-where M-s is the saturation magnetization and K-eff is the effective magnetocrystalline anisotropy constant-along with the expected distribution of both Mn and Cu ions in the lattice. The temperature dependence of selectivity for a chosen frequency (f = 1.6 MHz) for the six investigated samples has also been studied. (c) 2005 Elsevier B.V. All rights reserved.