SYNTHESIS AND PROPERTIES OF NANOCRYSTALLINE SUPERPARAMAGNETIC GAMMA-FE2O3

Nanocrystalline maghemite (gamma-Fe2O3) was synthesized in a microwave plasma energized by a 915 MHz generator Precursor for this synthesis is water free FeCl3. The resulting particles were in the size range fr om 4 to 5 nm. Magnetic measurements revealed that the material synthes ized by the microwave plasma route is superparamagnetic. At a temperat ure of 300 K and a magnetic field of I T the magnetization of this mat erial was 2.7 Am-2/kg. Ar 10 K this value increased to 4.3 Am-2/kg. Ad ditionally, measurements of the Mossbauer effect were performed. As ex pected, these measurements showed a pure quadrupole splitting at room temperature and two predominantly magnetic sites at 4 K. The blocking temperature is around 80 K.