Effect of treatment conditions on structure and magnetodielectric properties of barium hexaferrites

BaFe12O19 were synthesized using usual ceramic technology in two stages. The structure and dielectric properties of the obtained samples after different processing conditions were the subject of study. At the final stage, the samples were thoroughly reground and pressed into pellets with different pressures. The unit cell parameters of the obtained samples were determined by X-ray diffraction method. The density of the sample pellets as a function of the applied pressure and sintering temperature was collected. The density of the initial sample pellets monotonously depends on the applied pressure. The density of the final sample pellets has a maximum at 1.055 GPa, after which a slight decrease was observed. Complex impedance spectra of all the obtained samples were measured in the frequency range of 10(-1) - 10(6) Hz. Different treatment conditions result in two ranges of impedance spectrum. The impedance decreases with increasing processing pressure up to 1.055 GPa, above which, it starts gradually decrease. Complex spectra of impedance were fitted with a complex nonlinear least squares method based on the Levenberg-Marquardt minimization algorithm.