Magnetic Properties and Hyperfine Interaction of BaSrCo₂(Fe1−xAlx)12O22 Hexaferrite

Polycrystalline BaSrCo2(Fe1−xAlx)12O22 (x = 0.00, 0.01, 0.05, and 0.10) samples were synthesized by polymerizable complex method. Based on the Rietveld refinement, crystal structures of the samples were found to be single-phased and determined to be rhombohedral with space group of R-3m. The hysteresis curves of the samples were measured under 15 kOe at various temperatures ranging from 4.2 and 295 K. It shows that they were not saturated with increasing Al ion contents due to the reduction of magnetic anisotropy. M15kOe was decreased with increasing Al ions contents. We expect that non-magnetic Al ions preferentially occupy the up-spin site of 18hVI, 3bVI, and 3aVI. The M¨ossbauer spectra of the samples were obtained at 295 K, and analyzed with sixsextets for Fe sites corresponding to the Y-type hexaferrite crystallography sites. The shows abrupt changes, and the shows abrupt decreases around x = 0.05 due to the coexistence of magnetic secondary phases.