中文摘要：

由一根微小的电线的脉搏激光脱离准备 nanoparticles 的一个新方法被报导，；纯磁赤铁矿(γ - Fe2O3 ) nanoparticles 被这个方法在 N2 的混合煤气的流动综合；在气压的 O2。获得的γ - Fe2O3 nanopartiles 在在直径的 5 ～ 80 nm 的 runge；在形状大部分球形。结构的特征；nanoparticles 的形态学被 XRD 描绘；TEM 分别地。而且，在 300 ～ 773 K 的温度范围的获得的γ - Fe2O3 nanopartiles 的磁性被调查。试验性的结果证明磁滞现象循环的方形值与增加温度减少。两 coercivity；γ - Fe2O3 nanoparticles 表演的浸透磁化有从γ - Fe2O3 增加温度直到转变的出现到α - Fe2O3 的一个常常减少的趋势。在 773 K 的温度，特别，γ - Fe2O3 开始转变到α - Fe2O3 阶段；磁滞现象环变得打开。

英文摘要：

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 .