Effect of Pr3+ substitution on the microstructure, specific surface area, magnetic properties and specific heating rate of Ni0.5Zn0.5PrxFe2−xO4 nanoparticles synthesized via sol–gel method

A series of Ni–Zn ferrite nanoparticles with a nominal composition of Ni0.5Zn0.5PrxFe2−xO4 (x = 0.000–0.100 with steps of 0.025) has been synthesized by a sol–gel method. The effect of composition and calcination temperature on the morphology, specific surface area, magnetic properties and specific heating rate has been studied. The Ni–Zn–Pr ferrites have a single spinel (NZF) phase at Pr loadings below 5 at%. A minor amount of an orthorhombic PrFeO3 phase is present in the Ni–Zn–Pr ferrites at Pr loadings above 5 at%. At a Pr loading of 10 at%, the specific surface area increases six-fold as compared to that of the non-doped Ni0.5Zn0.5Fe2O4 sample. As the Pr loading increases, the saturation magnetization, remnant magnetization and coercivity increase and reach the maximum at x = 0.05 and then decrease. The maximum values of these parameters are 67.0 emu/g, 9.7 emu/g and 87.2 Oe, respectively. Under radiofrequency field (frequency: 295 kHz, intensity: 500 Oe), the highest heating rate of 1.65 K/s was observed over the sample with x = 0.025 which is 2.5 times higher than that of Ni0.5Zn0.5Fe2O4