Structural, Magnetic, and Dielectric properties of Sr4Fe6O13 ferrite prepared of small crystallites

Abstract A stable Sr4Fe6O13 was prepared as small crystallites by auto-combustion of a sol-gel in air followed by annealing the later at pertinent temperatures. A green sample, as annealed at elevated temperatures, yields a single Sr4Fe6O13 phase of tailored magnetic properties. The structural, morphological, magnetic and electrical properties were investigated by X-ray diffraction, transmission electron microscopy, vibrating sample magnetometer, and broadband dielectric spectrometer. Hard magnetic Sr4Fe6O13 properties arise with saturation magnetization Ms = 12.4 emu/g, coercivity Hc = 3956.7 Oe and squareness 0.512. Studies made at low temperatures reveals Ms decreasing on increasing temperature from 17.5 emu/g at 85 K down to 12.4 emu/g at 305 K, while Hc rises from 1483 Oe at 85 K to 1944 Oe at 305 K. The ac-conductivity follows the Jonscher relation. The dc-conductivity at high temperatures/low frequencies exhibits a plateau and it depends linearly on a characteristic frequency according to the Barton-Nakajima-Namikawa) relation.