Magnetic and dielectric properties of Bi3+ substituted SrFe12O19 hexaferrite

Abstract

In the present study, SrBixFe12−xO19 (0.0≤x≤1.0) nanomaterials were successfully synthesized by using chemical co-precipitation method. Products were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Vibrating sample magnetometer (VSM), Mössbauer spectroscopy, AC conductivity and dielectric measurements. The crystal structural information studied by X-ray diffraction (XRD) indicated the formation of single phase pure hexagonal structure, while electron-dispersive X-ray spectroscopy (EDX) revealed the stoichiometric ratio among Bi, Sr, Fe elements. The crystallite sizes of the products were in the range of 65–82 nm. VSM analysis showed a tendency in saturation magnetization as Bi2O3 concentration raises, which can be ascribed to preferential site occupied by Bi3+ ions. The frequency-dependent ac conductivity plots exhibited similar trends for all samples. A significant temperature-dependent behavior was only observed at low and medium frequencies. The replacement of non-magnetic Bi3+ ions by Fe3+ ones having magnetic moment of 5 µB decrease the magnetic moment of 4f1 site. The AC conductivity increases with frequency as hopping of the charge carriers increases between Fe2+and Fe3+. The DC conductivity exhibited an improvement with increasing temperature and Bi content, and the highest conductivity was measured as 2.84×10−9 S cm−1 for x=0.8 at 120 °C. The variation of dielectric constant, dielectric loss and tangent loss was observed with the frequency and temperature due to change of electrical conductivity as x changes.