Structural and magnetic behavior of Pr-substituted M-type hexagonal ferrites synthesized by sol-gel autocombustion for a variety of applications

A series of M-type hexaferrites with chemical formula Ba0.25Sr0.75PrxFe12−xO19 (x=0.00, 0.05, 0.10, 0.15, 0.20, 0.25) were synthesized using sol-gel autocombustion method. The samples were pre-sintered at a temperature of 800 °C for 3 h and were finally sintered at 1200 °C for 1 h at the heating rate of 10 °C/min. The thermal properties of the specimen have been investigated by thermogravimetric and differential thermal analyses. The structures and micrographs of the samples were systematically examined by X-ray diffraction and scanning electron microscopy, respectively. Vibrating sample magnetometer was also used in order to study the magnetic parameters of these ferrites. The hard magnetic behavior was confirmed by M-H loops for all the samples except for the sample with x=0.10 concentration which exhibits maximum saturation magnetization (Ms) and a few hundred oersteds of coercivity (Hc). Thus high Ms and low Hc cause to increase the permeability of the sample which is favorable for impedance matching in microwave absorption.