Tuning strontium M-type hexaferrite nanopowders coercive field through pH control

Monophasic strontium M-type hexaferrite powders have been successfully synthesized using a citrate precursor sol-gel method. The effect of the pH of the starting solution on the structural and magnetic properties was studied. XRD analysis, SEM imagery and magnetometry measurements were carried out to characterize the obtained powders. Results showed that pH value had an insignificant effect on the saturation magnetization Ms, the remanence Mr and the Mr/Ms ratio. It has also been noticed that the lattice parameters a and c were slightly affected by the pH variation. The coercive field Hc and the crystallite size D were affected by the pH value reaching a maximum value of Hc = 0.68 T. SEM imagery revealed that the particles shape and size were strongly dependent on pH value.