Magnetic properties of nanosize NiFe2O4 particles synthesized by pulsed wire discharge

Nanosize particles of nickel ferrite, NiFe2O4, have been successfully synthesized by pulsed wire discharge (PWD). In PWD, a simple circuit consisting of a capacitor and a gap switch drives the discharge. The wires of Ni and Fe were simultaneously discharged in a chamber filled with oxygen. The particles floating in the ambient gas were collected by pumping the gas through a membrane filter, and subjected to further analysis. The specific surface area of the particles were measured by the Brunauer-Emmet-Teller (BET) method. X-Ray diffraction showed the formation of NiFe2O4 and the inclusion of NiO. The NiO inclusion was estimated to be 18 vol.%. Magnetization hysteresis was measured for the particles synthesized at 600 torr. X-Ray diffraction and BET measurements reveal that particle size increases with increase in oxygen pressure. The saturation magnetization was found to be 33 emu/g for the particle with 45 nm in the size. (C) 2002 Elsevier Science B.V. All rights reserved.