Effect of superparamagnetic interaction on the magnetic heating efficiency of Co 0.3 Zn 0.7 Fe 2 O 4 and Co 0.5 Zn 0.5 Fe 2 O 4 nanoparticles

This work focused on the effect of dipolar interactions between particles on the magnetic heating efficiency of nanoferrites under an alternating magnetic field. The low-temperature hydrothermal method was adopted to obtain nanoparticles composed of Co0.3Zn0.7Fe2O4 and Co0.5Zn0.5Fe2O4. The single-phase spinel structure of the samples was confirmed from X-ray diffraction data via Rietveld refinement technique. Transmission electron microscopy showed that the Co0.3Zn0.7Fe2O4 and Co0.5Zn0.5Fe2O4 nanoparticle ferrites had sizes of 10 and 12 nm, respectively. Blocking temperature showed a nonlinear and logarithmic decreasing tendency as a function of the applied magnetic field. The value of coercivity decreased with temperature and conformed to the Callen and Callen law. Dipolar interactions among nanoparticles caused magnetization to deviate from standard superparamagnetic behavior. This characteristic can be explained using the interacting superparamagnetic model. As a consequence, dipolar interactions reduced the specific loss power of Co0.3Zn0.7Fe2O4 and Co0.5Zn0.5Fe2O4 under 80 Oe at 178 kHz with increasing nanoparticle concentration. © 2020 Elsevier B.V.