Investigation of crystal structure, Raman spectroscopy and magnetic properties of La-Zn substituted oriented M-type hexagonal barium ferrites

Abstract

M-type hexagonal barium ferrite (BaM) has received much attention in the application of self-biased microwave devices because of its large anisotropic field (Ha) and high saturation magnetization (Ms), but the increased Ha inevitably increases the microwave magnetic loss of the device. In addition, the devices need to have a high Ms for high frequency applications. To address these issues, we used La3+ and Zn2+ instead of Ba2+ and Fe3+ ions to modulate the Ha and Ms of BaM, respectively. Ba1-yLayFe12-xZnxO19 (x=y=0.1–0.5) M-type hexagonal ferrite was synthesised by conventional solid-phase methods. The La-Zn co-substituted BaM samples were shown to be purely single phase by X-ray diffraction (XRD) analysis. The lattice parameters, specific surface area, crystallite size, dislocation density and microstrain of the samples were also calculated using the XRD data. Furthermore, La3+ and Zn2+ can not only modulate the sample Ha and Ms between 10,214–12,102 Oe and 62.94–78.23 emu/g, respectively, while making the sample more denser. At x=0.3 BaM detects relatively satisfactory properties: large Ms=63.12 emu/g, suitable Ha=10,214 Oe and Hc=2248.87 Oe, high Mr/Ms=0.832 and narrow ferromagnetic resonance linewidth (= 903 Oe), which provide good candidates for next-generation self-biased and low-loss microwave wave devices.