Magnetic properties of Zn-substituted Y-type hexaferrites, Ba2ZnxFe2−xFe12O22

We report the magnetic properties of Zn-substituted barium Y-type hexaferrites with the Zn substituent, x, ranging from 0.5 to 2.0 in Ba2ZnxFe2−xFe12O22. After high-temperature annealing and subsequent furnace-cooling, single-phase samples with x = 0.5, 1.0, 1.5 could be successfully prepared in a reduced oxygen atmosphere (PO2 = 10−3 atm) while the single-phase was obtainable only from the sample with x = 2.0 in air. With increasing x from 0.5 to 2.0, both a lattice parameters (≈0.32%) and unit cell volumes (Vcell) (≈0.51%) were linearly increased but c lattice parameters (≈0.12%) were linearly decreased, which is in good agreement with the Vegard's law, indirectly supporting a successful formation of Ba2ZnxFe2−xFe12O22-type solid solutions. The saturation magnetization (Ms) was first increased with increasing x from 0.5 to 1.0 and then decreased up to x = 2.0. Thus, the highest Ms value of 44.7 emu/g was obtainable from the sample of x = 1.0 sintered at 1300 °C for 2 h in the low PO2 of 10−3 atm. These results are attributable to the site preference of Zn2+ ions for the tetrahedral sites of Y-type hexaferrites.