Structural, Magnetic, and Dielectric properties of Sr(4)Fe(6)O(13) ferrite prepared of small crystallites

A stable Sr(4)Fe(6)O(13) 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 Sr(4)Fe(6)O(13) 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 Sr(4)Fe(6)O(13) properties arise with saturation magnetization M(s) = 12.4 emu/g, coercivity H(c) = 3956.7 Oe and squareness 0.512. Studies made at low temperatures reveals M(s) decreasing on increasing temperature from 17.5 emu/g at 85 K down to 12.4 emu/g at 305 K, while H(c) 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.