Effects of Pr-Al co-substitution on the magnetic and structural properties of M-type Ca-Sr hexaferrites

Abstract

In this research, a series of Pr-Al co-substituted M-type hexaferrites with the chemical composition of Ca0.4Sr0.6-xPrxFe12.0-yAlyO19 (0.00 ≤ x ≤ 0.40, 0.00 ≤ y ≤ 0.60) were synthesized by the standard ceramic method. The phase identification of the samples was confirmed by X-ray diffraction analysis. A single magnetoplumbite phase is exhibited in the hexaferrites with the substitutiom of Pr (0.00 ≤ x ≤ 0.32) and Al (0.00 ≤ y ≤ 0.48) contents. For the hexaferrite containing Pr (x = 0.40) and Al (y = 0.60), an impurity phase α-Fe2O3 is observed in the structure. The morphology of the hexaferrites was analyzed by field emission scanning electron microscopy (FE-SEM). FE-SEM micrographs show that the hexaferrites with different Pr-Al contents have formed hexagonal structures, and the grain size of the magnets decreases with increasing Pr-Al content. A magnetic property measurement system was used to measure the magnetic properties of the hexaferrites. The remanence (Br) and maximum energy product [(BH)max] decrease with increasing Pr-Al content (0.00 ≤ x ≤ 0.40, (0.00 ≤ y ≤ 0.60). The intrinsic coercivity (Hcj) increases with increasing Pr-Al content (0.00 ≤ x ≤ 0.40, (0.00 ≤ y ≤ 0.60). The magnetic induction coercivity (Hcb) and Hk/Hcj ratio first increase with increasing Pr-Al content (0.00 ≤ x ≤ 0.24, 0.00 ≤ y ≤ 0.36) and then decrease with increasing Pr-Al content (0.24 ≤ x ≤ 0.40, 0.36 ≤ y ≤ 0.60).