Superparamagnetic Properties of Zn0.5Ni0.5Fe2O4 Nanoparticles

Zn0.5Ni0.5Fe2O4 nanoparticles have been prepared by a sol-gel method. The structural and magnetic properties have been investigated by XRD, SEM, and Mbssbauer spectroscopy, VSM. Zn0.5Ni0.5Fe2O4 powder that was annealed at 300 degrees C has spinel structure and behaved superparamagnetically at room temperature. The estimated size of superparammagnetic Zn0.5Ni0.5Fe2O4 nanoparticle is around 7 nm. The hyperfine fields of the A and B patterns at 4.2 K were found to be 510 and 475 kOe, respectively. The blocking temperature (T-B) of superparammagnetic Zn0.5Ni0.5Fe2O4 nanoparticle is about 90 K. The magnetic anisotropy constant and relaxation time constant of Zn0.5Ni0.5Fe2O4 nanoparticle were calculated to be 1.6x 10(6) ergs/cm(3).