Phase analysis and cation distribution correlated with magnetic properties of spinel Ba1-xSrxFe2O4ferrites prepared at different annealing temperatures

Nano Ba(1-x)Sr(x)Fe(2)O(4)samples were prepared by sol-gel autocombustion procedure. The phases developed due to different annealing temperatures and Sr-substitution amounts were determined by X'Pert HighScore Plus software. The effect of composition and annealing temperature on the lattice parameters and the crystallite size was investigated using X-ray diffraction technique. Rietveld analysis has been performed to determine the cation distribution between different crystallographic sites upon the Sr-substituted BaFe(2)O(4)sample. Sr ion was found to prefer residing at 4a(II) site and the coordinates of this site dramatically changed with the Sr content (x). Fourier transform infrared spectrometry (FTIR) confirmed the orthorhombic structure of BaFe(2)O(4)and the presence of the hexagonal structure ascribed to Ba(0.5)Sr(0.5)Fe(2)O(4)for Sr-substituted samples. BaFe(2)O(4)and Ba(0.5)Sr(0.5)Fe(2)O(4)samples prepared at 700 degrees C revealed hysteresis loop with wasp-waist nature. The saturation magnetization and coercivity changed irregularly upon varying the annealing temperatures. For Ba(1-x)Sr(x)Fe(2)O(4)samples annealed at 900 degrees C, the saturation magnetization changed depending on the amount of Sr doping in the sample. Ba(0.5)Sr(0.5)Fe(2)O(4)has the lowest coercively (424 Oe) at 700 degrees C annealing temperature, while its highest saturation magnetization (3.83 emu/g) is obtained at 1050 degrees C. Many factors were considered to explain the irregular behavior of coercivity in the Ba(1-x)Sr(x)Fe(2)O(4)nano system.