Magnetic and microstructural properties of M-type strontium hexaferrites with Pr–ZnAl substitution

Abstract We have investigated the influence of Pr–ZnAl substitution on the magnetic and microstructural properties of M-type strontium hexaferrites Sr 1.0-x Pr x Fe 12.0-x (Zn 0.5 Al 0.5 ) x O 19 (0.0 ≤ x ≤ 0.5) synthesized by the standard ceramic method. X-ray diffraction (XRD) was carried out to determine the crystal structure and the phase identification of the hexaferrites showed that a single magnetoplumbite phase was exhibited in the hexaferrites with Pr–ZnAl content (x) from 0.0 to 0.4 and impurity phase α-Fe 2 O 3 was observed in the structure when Pr–ZnAl content (x) = 0.5. The morphology of the hexaferrites was analyzed by a field emission scanning electron microscopy (FE-SEM). The representative FE-SEM micrographs showed that the particles were regular hexagonal platelets and the average grain size basically kept unchanged with increasing Pr–ZnAl content (x). A magnetic property measurement system was used to measure the magnetic properties of the hexaferrites. The remanence ( B r ), maximum energy product [( BH ) max ] and H k / H cj ratio decreased with increasing Pr–ZnAl content (x) from 0.0 to 0.5. The intrinsic coercivity ( H cj ) and magnetic induction coercivity ( H cb ) first increased with increasing Pr–ZnAl content (x) from 0.0 to 0.1, and decreased with increasing Pr–ZnAl content (x) from 0.1 to 0.2, and then increased when Pr–ZnAl content (x) ≥ 0.2.