| Popis: |
Micro-/nano-sized BaFe12O19 particles were synthesized by the hydrothermal method, and the effects of Ba/Fe ratio, OH−/Cl− ratio, reaction time, and reaction temperature on the phase composition, static, and millimeter (mm)-wave magnetic properties of BaFe12O19 were studied. Phase composition analysis shows that non-stoichiometric and iron-deficient precursor is necessary to form $M$ -type BaFe12O19 (BaM) of high purity under the optimized synthesis condition. Otherwise, the products should contain the trace of either $\alpha $ -Fe2O3 impurity phase or Fe3O4 transitional phase. It is found that the saturation magnetization (30–50 emu/g) and the coercivity values (300–600 Oe) of all the samples lie in the range of bulk BaM hexaferrite. The frequency dependence of the complex permeability of BaM composites has been studied in the Ka-band (26.5–40 GHz). With ferromagnetic resonance efficiently controlled by phase composition, the proposed BaM composites show potential application at mm waves. |
