Synthesis and magnetic properties of strontium hexaferrite from celestite ore

Nanocrystalline strontium hexaferrite (SrFe(12)O(19)) powders have been synthesized from Egyptian celestite ore (SrSO(4)), as a source of strontium, via co-precipitation route. The raw celestite ore was first dissolved in hydrochloric acid to remove about 10% CaO and the acid soluble impurities associated with the ore. Then, the treated celestite was washed and dried followed by a reduction with carbon to give acid-water soluble strontium sulfide SrS. The ferrite precursors were obtained from a precipitation of the produced SrS dissolved in dil. HCl and pure ferric chloride at pH 10 using 5 M sodium hydroxide. These precursors were annealed at 1000 degrees C for constant time 2 h in open atmosphere. The effect of Fe(3+)/Sr(2+) mole ratio on the formation, crystallite size, morphology and magnetic properties were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and VSM, respectively. The results obtained showed that the single phase SrFe(12)O(19) powders was achieved at the Fe(3+)/Sr(2+) mole ratios 8.57 and 8.00 at annealing temperature 1000 degrees C for 2 h. The maximum saturation magnetization (74.15 emu/g) was achieved at the Fe(3+)/Sr(2+) mole ratio to 8.57 and annealing temperature 1000 degrees C due to the formation of a uniform-like hexagonal shape structure. Moreover, wide coercivities can be obtained at different synthesis conditions (2011-3504 Oe). (C) 2008 Elsevier B.V. All rights reserved.