MÖssbauer Studies of Superparamagnetic Ni$_{0.5}$Zn$_{0.5}$Fe$_{2}$O $_{4}$ Nanoparticles

Superparamagnetic Ni
_0.5
Zn
_0.5
Fe
₂
O
₄
nanonoparticle is fabricated by a sol-gel method. The magnetic and structural properties as a function of annealing temperature were characterized by using X-ray diffactometry (XRD), Mossbauer spectroscopy, and vibrating sample magnetometry (VSM) as well as scanning electron microscope (SEM). Ni
_0.5
Zn
_0.5
Fe
₂
O
₄
powder that was annealed at 573 K has spinel structure and behaved superparamagnetically at room temperature. The estimated size of superparammagnetic Ni
_0.5
Zn
_0.5
Fe
₂
O
₄
nanoparticle is around 7 nm. The hyperfine fields of the A and B patterns at 4.2 K were found to be 514 and 481 kOe, respectively. The blocking temperature (T
_B
) of superparammagnetic Ni
_0.5
Zn
_0.5
Fe
₂
O
₄
nanoparticle is about 90 K. The magnetic anisotropy constant of Ni
_0.5
Zn
_0.5
Fe
₂
O
₄
nanoparticle were calculated to be 1.6times10
⁶
erg/cm
^-3
.