Magnetic Properties of γ-Fe2O3 Nanoparticles Prepared by Laser Ablation

A new method of preparing nanoparticles by pulsed-laser ablation of a tiny wire was reported, and pure maghemite （ γ-Fe2 O3 ） nanoparticles were synthesized by this method in a mixed gas flux of N2 and O2 at atmospheric pressure. The obtained γ-Fe2 O3 nanopartiles were in the range of 5 to 80 run in diameter and largely spherical in shape. Structural characteristics and morphologies of the nanoparticles were characterized by XRD and TEM , respectively. Moreover, magnetic properties of the obtained 7- Fe, O3 nanopartiles in the temperature range of 300 to 773 K were investigated. The experimental results demonstrate that the squareness value of the hysteresis loop decreases with increasing temperature. Both the coercivity and the saturation magnetization of the γ-Fe2 O3 nanoparticles show a constantly decrensing trend with increasing temperature up to the occurrerwe of the transformation from γ-Fe2O3 to α-Fe2O3. Especially, at the temperature of 773 K, the γ-Fe, O3 begins to transform to the α-Fe2 O3 phase and the hysteresis loop becomes unclosed .

Magnetic properties of γ-Fe2O3 nanoparticles prepared by laser ablation

A new method of preparing nanoparticles by pulsed-laser ablation of a tiny wire was reported, and pure maghemite (γ-Fe₂O₃) nanoparticles were synthesized by this method in a mixed gas flux of N₂ and O₂ at atmospheric pressure. The obtained γ-Fe₂O₃ nanopartiles were in the runge of 5 to 80 nm in diameter and largely spherical in shape. Structural characteristics and morphologies of the nanoparticles were characterized by XRD and TEM, respectively. Moreover, magnetic properties of the obtained γ-Fe₂O₃ nanopartiles in the temperature range of 300 to 773 K were investigated. The experimental results demonstrate that the squareness value of the hysteresis loop decreases with increasing temperature. Both the coercivity and the saturation magnetization of the γ-Fe₂O₃ nanoparticles show a constantly decreasing trend with increasing temperature up to the occurrence of the transformation from γ-Fe₂O₃ to α-Fe₂O₃. Especially, at the temperature of 773 K, the γ-Fe₂O₃ begins to transform to the α-Fe₂O₃ phase and the hysteresis loop becomes unclosed. Funded by the National Natural Science Foundation of China (No. 59981002)