Superparamagnetic properties Ni-Zn ferrite for nano-bio fusion applications

Ni0.7Zn0.3Fe2O4 nanoparticles were fabricated by a sol-gel method. Ni0.7Zn0.3Fe2O4 powders annealed at 300 degrees C compose a spinel structure and behaved superparamagnetically, while annealed at 400 and 500 degrees C have typical spinel structure with ferrimagnetism in nature. The mean size of Ni0.7Zn0.3Fe2O4 nanoparticle is about 11 nm. The hyperfine fields at 13 K for the tetrahedral (Lambda) and the octahedral (B) patterns were found to be 499 and 523 kOe, respectively. Blocking temperature (T-B) of Ni0.7Zn0.3Fe2O4 nanoparticle is about 260 K. Also, temperature increased up to 43 degrees C within 7 min under AC magnetic field of 7 MHz. (C) 2006 Elsevier B. V. All rights reserved.