Effects of Calcination Temperature and Rare Earth Substituting on the Crystal Structure and Magnetic Properties of Sr0.95Re0.05Fe12O19 (Re = La, Pr, Nd, Dy, Yb) M-type Hexaferrites

Rare-earth substituted nanocrystalline hexagonal strontium ferrites with chemical formula Sr1 − xPrxFe12O19 (0 ≤ x ≤ 0.1) and Sr0.95Re0.05Fe12O19 (Re = La, Pr, Nd, Dy, Yb), were prepared by sol-gel autocombustion method. The effects of calcination temperature, rare earth ion concentration and rare earth ion radius on the structure and magnetic properties of nano-sized hexagonal strontium ferrites were investigated. X-ray diffraction (XRD) and Vibrating sample magnetometer (VSM) were applied for the systematical investigation of phase composition, crystal structure and magnetic properties of the samples respectively. The suitable calcination temperature of nanocrystalline strontium ferrites was determined to be 900 ℃, which was attributed to the relationship between the calcination temperature and the rotation of the domain wall. The coercivity (Hc) of Sr1 − xPrxFe12O19 reached a maximum at x = 0.05 and the saturation magnetization (Ms) decreased with the increase of Pr substituting content. This reduction followed the spin canting and magnetic dilution which results in the dislocation of super exchange interactions. For Re-substituted samples, the Hc increased with the decreasing ionic radius of substituted elements, while the Ms slightly decreased in comparison to the non- substituted sample. The synthesized samples could be used in permanent magnets, high-density magnetic recording medium, and microwave equipment.