Khalid Mehmood Ur Rehman

Structure and magnetic analyses of hexaferrite Sr 1−x La x Fe 2 2+ Fe 16 3+ O 27 prepared via the solid-state reaction

W-type ferrite Sr1−xLaxFe22+Fe163+O27 (x = 0.00, 0.05, 0.08, 0.10, 0.13 and 0.15) powders and magnets were prepared via the solid-state reaction in nitrogen. Phase components of the powder samples were examined by X-ray diffraction (XRD). XRD results demonstrated the appearance of pure phase hexagonal crystal structure and calculate the lattice constants c and a, c/a ratio, cell volume (Vcell), X-ray density (dX-ray) and crystallite size (D) parameters according to XRD data. Scanning electron microscopy (SEM) was used to observe the morphology of the magnets. SEM analyses revealed the hexagonal morphology of the ferrites. The magnetic characteristics of magnetic powders were measured by a vibrating sample magnetometer (VSM), and the magnetic characteristics of magnets were also measured by a permanent magnetic measuring equipment. The results indicate that, the synthesized samples with a low coercive force value and a considerable saturation magnetization are best able to make optical read-out of the magnetic storage information in erasable video and audio discs.

Influence of heat treatment temperatures on microstructure and characterization of BaFe22+Fe15.63+O26.4 hexaferrite

A series of W-type hexagonal ferrites with composition BaFe22+Fe15.63+O26.4 at different temperatures was synthesized via a ceramic process in a reducing atmosphere during the whole process of calcination and sintering. The phase identification of magnetic powders was performed by X-ray diffraction. The result of XRD confirmed the appearance of a pure phase hexagonal crystal structure with temperature from 1290 to 1330 °C. The microstructures of the magnets were investigated by using a HS-4800 scanning electron microscopy. The magnetic properties of the magnets were measured by a permanent magnetic measurement equipment. B–H curves show that the magnetic properties such as remanence, magnetic induction coercivity, intrinsic coercivity, saturation magnetization and maximum energy product are significantly affected by calcination and sintering temperatures. The optimized sintering and calcination temperatures are 1280 and 1300 °C, respectively.