Investigation of Sr-substituted BaFe2O4 Synthesized by Sol-Gel Method

Abstract

In the present work, Sr-substituted samples of single phase spinel mono ferrites with formula Ba1-xSrxFe2O4 (x = 0.00, 0.33, 0.67, 1.00) were synthesized using sol-gel auto combustion method. A sample with x = 0.00 was chosen to heat treat at different temperatures (at 100oC, 300oC, 400oC, 600oC and 700oC for 4h) in order to confirm the single phase formation of the samples. The sample heat treated at these temperatures was then investigated by X-ray diffraction (XRD) analysis. The results show that single phase sample can be successfully synthesized at a temperature of 600oC which is much lower than the same structured samples reported in earlier literature. All the synthesized compositions of these samples were then sintered at 700°C for 4h for better crystallinity. These samples were then investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometery (VSM), Vector network analysis (VNA). X-ray diffraction analysis reveals that single-phase monobarium ferrites can be obtained at 600°C-700°C temperature for 4h. From XRD patterns, different structural parameters such as lattice parameters (a,b,c), cell volume (V) and X-ray diffraction density as a function of Sr2+ ions at Ba2+ sites were calculated. Scanning electron microscopy results show that the grain size increases as the temperature is increased because it is well known that increased heat treatment promotes the grain growth in ferrites. Fourier transform infrared spectroscopy analysis gives us information about different groups of chemical compounds present in our material. From M-H loops of the samples (with x=0.0, 0.33, 0.67 and 1.00) measured by VSM, different magnetic parameters such as saturation magnetization (Ms), remanance (Mr), coercivity (Hc) and magnetic moment (nB) were calculated. The value of coercivity (Hc) increases as the Sr substitution was increased in ferrite materials. In addition, the variation of different dielectric parameters (real permittivity, imaginary permittivity, real permeability, imaginary permeability, ac conductivity and loss tangent) as a function of frequency (-6GHz) has been discussed in the present work.