Superparamagnetic Properties of Nanoparticles Ni 0.9 Zn 0.1 Fe 2 O 4 for Biomedical Applications

Nanoparticles Ni_(0.9)Zn_(0.1)F₂O₄ is fabricated by a sol-gel method. The magnetic and structural properties of powders were investigated with XRD, SEM, Mossbauer spectroscopy, and VSM. Ni_(0.9)Zn_(0.1)F₂O₄ powders annealed at 300 ℃ have a spinel structure and behaved superparamagnetically. The estimated size of Ni_(0.9)Zn_(0.1)F₂O₄ nanoparticle is about 10 ㎚. The hyperfine fields at 13 K for the A and B patterns are found to be 533 and 507 kOe, respectively. The ZFC curves are rounded at the blocking temperature (T_B) and show a paramagnetic-like behavior above T_B. T_B of Ni_(0.9)Zn_(0.1)F₂O₄ nanoparticle is about 250 K. Nanoparticles Ni_(0.9)Zn_(0.1)F₂O₄ annealed at 400 and 500 ℃ have a typical spinel structure and is ferrimagnetic in nature. The isomer shifts indicate that the iron ions were ferric at the tetrahedral (A) and the octahedral (B). The saturation magnetization of nanoparticles Ni_(0.9)Zn_(0.1)F₂O₄ annealed at 400 and 500 ℃ are 40 and 43 emu/g, respectively. The magnetic anisotropy constant of Ni_(0.9)Zn_(0.1)F₂O₄ annealed at 300 ℃ were calculated to be 1.6 × 10^6 ergs/㎤.