Shuangjiu Feng

Structural and magnetic properties of Sr1−x La x Fe12−x (Cu0.5Co0.5) x O19 hexaferrites prepared by the solid-state reaction method

Hexaferrite Sr1−xLaxFe12−x(Cu0.5Co0.5)xO19 (0 ≤ x ≤ 0.50) magnetic powders and magnets were synthesized by the solid-state reaction method. The phase compositions of magnetic powders were investigated by X-ray diffraction. The single magnetoplumbite phase is obtained in magnetic powders with x from 0 to 0.40. At x = 0.50, CoFe2O4, and α-Fe2O3 were observed. The morphology of the materials was characterized by a field-emission scanning electron microscopy. The particles were hexagonal platelets. Magnetic properties of the materials were measured by a permanent magnetic measure equipment. The remanence of the materials increases with x from 0 to 0.50. However, the intrinsic coercivity and magnetic induction coercivity of the materials increase with x from 0 to 0.15, and decreases when x varies from 0.15 to 0.50. Accordingly, the maximum energy product of the materials first increases with x from 0 to 0.35, and then decreases when x exceeds 0.35.

Structural and magnetic properties of La-substituted strontium W-type hexagonal hexaferrites

W-type strontium hexaferrites with chemical composition of Sr1−xLaxZn2Fe16O27 (x = 0–0.25) were synthesized by traditional ceramics process. Effects of the substituted amount x of La3+ on the ferrites microstructure and magnetic properties have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and a magnetic properties test instrument. As a result, at x ≤ 0.20, all samples are single phase after the La substitution. At x = 0.25, another phase of La2O3 is present. In addition, the maximum values of the remanence (Br) and maximum energy product ((BH)max) for the magnets have been obtained at x = 0.10. The maximum value of the intrinsic coercive force (Hcj) and magnetic induction coercivity (Hcb) for the magnets has been obtained at x = 0.15.

Improvement of magnetic properties of Cr3+ substituted SrFe12O19

Abstract M type strontium hexaferrites SrFe12 − xCrxO19 (x = 0.0–0.6) were prepared by the ceramic process. The structure, morphology and magnetic properties of the samples were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and B–H hysteresis curve measurements. The XRD patterns show the formation of the M-type hexaferrite phase in the pre-sintered samples with non-magnetic phase, α-Fe2O3. The SEM results indicate that the Cr substitution does not obviously affect the structure of strontium ferrite. The results of magnetic mensuration, especially for the SrFe11.8Cr0.2O19 samples, reveal that rather high magnetic properties can be obtained in the sintering temperature range of 1135–1165°C.