Influence of RE3+ co-substitution on the structure and magnetic properties of Sr0.82RE0.18Fe12O19 (RE: La0.18−xPrx) ferrites

• Sr0.82RE0.18Fe12O19 (RE: La0.18−xPrx) ferrites were prepared via autocombustion technique.
• The Hc and Tc were observed to be rare-earth ion anisotropy dependent.
• Highest Hc and Tc were observed for Pr3+ doped samples as Pr ion has high anisotropy.
• The magnetization show continuous decline with Pr3+ doping.
• Conversion Fe3+ to Fe2+ and noncollinearity of spins lead to Ms reduction.

The influence of replacing Sr2+ ions by RE3+ ions (RE: La and Pr) on the structural and magnetic properties of Sr0.82(La0.18−xPrx)Fe12O19 hexaferrite prepared via autocombustion method is presented in this study. The effect of codoping La3+ (non-magnetic) and Pr3+ (magnetic) ions for Sr2+ in Sr-Ferrite is studied using X-ray diffraction, magnetometry, and 57Fe Mössbauer spectroscopy. The X-ray diffraction patterns show the samples are single phase hexaferrites with magnetoplumbite structure without other secondary phases. A continuous decline in saturation magnetization and an increase in coercivity is observed upon replacing La with Pr. Maximum coercivity, Hc ∼ 5.97 kOe, and Curie temperature, Tc ∼ 732 K was obtained for x = 0.18 samples. A decline in hyperfine field values at all Fe3+ sites is observed with Pr3+ substitution. The quadrupole shift and isomer shift values of Fe3+ sites reflect subtle charge variations resulting upon Pr3+ substitution. It is found that the appropriate amount of La increases the saturation magnetization while Pr improves Hc and Tc as compared to undoped Sr-Ferrites.