Structural and electrical properties of Pb-doped Sr-hexa ferrites

The effect of Pb doping on the structural and electrical properties of Sr0.5Pb0.52+Fe12-xPbx3+O19 (where x = 0.0, 0.2, 0.4, 0.6, 0.8, 1.0) hexaferrites, prepared by solid state reaction method, were investigated. The X-ray analysis confirmed the multi phase including PbO and hematite (alpha-Fe2O3) formation. The lattice parameters were found to increase, which is attributed to the ionic size differences of cations involved. X-ray density was also found to increase with the composition (x). The DC electrical resistivity (rho) was measured as a function of temperature from 298 K to 575 K using two probe technique. The variation of AC conductivity (sigma(ac)) with frequency ranging from 80 Hz to I MHz shows that electrical conductivity in these ferrites is mainly due to the electron hopping mechanism. The variation of dielectric constant (epsilon') and loss tangent (tan delta) in the frequency range 80 Hz to 1 MHz was studied. The conduction phenomenon was explained on the basis of a small polaron hopping model. The confirmation of this phenomenon was made with the help of AC conductivity measurements. (C) 2007 Elsevier B.V. All rights reserved.