Investigation of magnetic properties of non-magnetic ion (Al, Ga, In) doped Ba2Mg0.5Co1.5Fe12O22

Abstract

Ba2Mg0.5Co1.5Fe12O22 (non-doped) and non-magnetic ion (Al, Ga, In) doped Ba2Mg0.5Co1.5(Fe0.99M0.01)12O22 (M-doped) polycrystalline samples were prepared by the solid-state reaction method. The crystal structures and magnetic properties of samples were investigated with x-ray diffractometer (XRD), vibrating sample magnetometer (VSM), and Mössbauer spectroscopy. The crystal structures of non-doped and M-doped samples were determined as hexagonal structures with R-3m space group by the Rietveld refinement. The unit cell volume (Vu) of non-doped sample was Vu = 1298.0 Å3, while those of M-doped samples (M = Al, Ga, In) were Vu = 1295.7, 1296.7, and 1299.9 Å3, respectively. From the magnetic hysteresis curves at room temperature, the saturation magnetization (Ms) and coercivity (Hc) of non-doped sample were found to be Ms = 28.0 emu/g and Hc = 255.4 Oe, but those of M-doped samples (M = Al, Ga, In) were Ms = 24.7, 28.4, 28.6 emu/g, and Hc = 222.0, 215.9, 190.7 Oe, respectively. From the temperature dependence of magnetization curves under 100 Oe between 4.2 and 740 K, all samples showed magnetic structure transitions. In addition Mössbauer spectra of all samples were recorded at various temperatures ranging from 4.2 to 750 K. Based on the isomer shift (δ) values of all samples, the charge states were found to be Fe3+ state at 295 K.