Effect of Gamma Radiation on Super paramagnetic Nano-Particles

Nguyen Thi Ai Thu

Background: Nanosized spinel ferrite particles, a kind of soft magnetic materials with structure formula of  MFe₂O₄ (M = divalent metal ion, eg. Mn, Mg, Zn, Ni, Co, Cu, etc.), are one of the most attracting class of materials due to their interesting and important properties such as low melting point, high specific heating, large expansion coefficient, low saturation magnetic moment and low magnetic transition temperature, etc [1], [2]. Because of these properties, the spinel ferrites have many technical applications such as in photoelectric device [3], catalysis [4], sensors [5], nano devices [6], microwave devices [7], [8] and magnetic pigments [9].

In this work, the synthesis of Fe₃O₄, NiFe₂O₄, MgFe₂O₄ nano-particles by coprecipitation method is reported. The influence of gamma radiation on magnetic properties of these superparamagnetic nano-particles is examined.

Methods: The samples were prepared  by coprecipitation route. The X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) were used to characterized the samples. In this study, we used ⁶⁰Co gamma radiation to emit on superparamagnetic materials.

Results: The result of XRD showed that the products were pure Fe₃O₄, NiFe₂O₄, MgFe₂O₄ particles. The hysteresis loop obtained from VSM measurements showed Fe₃O₄, NiFe₂O₄, MgFe₂O₄ superparamagnetic nanoparticles have an inverse spinel structure. From the SEM micrographs, it is proved that the nanoparticles obtained are cube like and rather uniform. The average particle size was changed under affecting of radiating and found to be in the range of 52 ¸ 54 nm that increased up to 48.6 ¸ 112% of 52 ¸ 54 nm that increased up to 48.6 ¸ 112%.

Conclusions: Nanosized ferrite particles were synthesized with coprecipitation route and were irradiated by ⁶⁰Co gamma radiation source. The result showed that magnetic properties and particles size changed.