Synthesis and properties of strontium hexa-ferrite ultrafine powders via a CTAB-assisted co-precipitation method

Single-phase SrM ultrafine powders with single-domain particle ranging from 200 to 400 nm in size were successfully synthesized by a cetyltrimethylammonium bromide (CTAB)-assisted co-precipitation method, and excellent magnetic properties with saturation magnetization of 68.6 A·m²·kg⁻¹ and coercive field of 0.5250 T are obtained. As CTAB content exceeds 5.0 wt%, the impurities emerge due to the deterioration of simultaneous precipitations of the starting materials and the deviation of Sr/Fe molar ratio from stoichiometry ratio in the local microdomains by employing CTAB in co-precipitation process. Also, the use of CTAB can effectively improve the homogeneities of Fe-precursor particles with Sr-precursor particles, exert surface barriers to inhibit interdiffusion, and constrain the crystal growth in the local microdomains during sintering, resulting in smaller particle sizes and more uniform particle size distribution.