Magnetic study of both nitrided and oxidized Co particles

Both nitrided and oxidized Co ultra-fine particles with average particle size from 15 to 60 nm were prepared by the gas-condensation technique. The size and temperature dependences of coercivity had been studied. The results shows that the coercivities are sensitive to the nitrided and oxidized Co particles In general, the magnetic properties of nitrided Co particles are better than that of the oxidized Co particles. For example, the shift of coercivity at 10 K of nitrided Co particles with average particle size of 20 nm was 2700 Oe, while only 2000 Oe for oxidized Co particles. A shifted hysteresis loop was observed below roughly 220 K.