Tuning the coercive field of strontium M-type hexaferrite nanopowders via pH control

Single-phase strontium M-type hexaferrite (SrFe12O19) nanopowders were successfully synthesized via a citrate precursor sol–gel method. This study investigates the effect of pH variation in the precursor solution on the structural, morphological, and magnetic properties of the resulting powders. X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometry (VSM) were employed to characterize the samples. The crystallite size, phase purity, and coercive field exhibited significant dependence on the precursor pH, while the saturation magnetization and remanent magnetization remained relatively stable. The optimal magnetic performance, including the highest coercivity of 0.68 T, was achieved at pH 1, which also produced the most homogeneous particle morphology. These results underscore the critical role of pH control in tuning the magnetic hardness and microstructure of SrM powders synthesized via sol–gel processing.