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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Synthesis of Magnetic Intermetallic FeAl Nanoparticles from a Non-Magnetic Bulk Alloy
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Synthesis of Magnetic Intermetallic FeAl Nanoparticles from a Non-Magnetic Bulk Alloy

机译：由非磁性块状合金合成磁性金属间铁铝纳米颗粒。

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We report the synthesis of intermetallic FeAl nanoparticles using the laser vaporization controlled condensation technique. The nanoparticles have an average particle diameter between 6 and 9 nm. Measurements of the d spacing from X-ray and electron diffraction studies confirm that the FeAl nanoparticles have the same crystal structure (B2) as the bulk FeAI. High-resolution TEM images reveal that the nanoparticles consist of a crystalline core encased within a thin amorphous layer formed upon the exposure of the particles to air. We also report the synthesis of FeAl oxide and carbide nanoparticles. The oxide nanoparticles have the hercynite FeAI2O4 composition and the carbide nanoparticles have the AlFe3Co·5 composition. While the crystalline bulk FeAI (20—30% weight Al) materials are nonmagnetic, the analogues nanoparticles are found to be ferromagnetic even well above room temperature. Coercivities of the order of 50 Oe almost independent of temperature are observed from room temperature down to 40 K, below which the coercivities values increase up to 700 Oe at 5 K. The nanoparticles show a definitive exchange anisotropy effect probably arising from the intersurface amsotropy at the adsorbed oxygen layers on these particles. The observed displacement of the hysteresis loops along the field and the magnetization axes are reversible with the direction of the applied field. The FeAl nanoparticles may lead to a novel form of advanced materials that combine high electrical resistivity, oxidation resistance, ductility and unique magnetic properties.
机译：我们报告了使用激光汽化控制缩合技术合成金属间FeAl纳米粒子。纳米颗粒的平均粒径在6至9nm之间。通过X射线和电子衍射研究d间距的测量结果证实，FeAl纳米颗粒具有与块状FeAI相同的晶体结构（B2）。高分辨率TEM图像显示，纳米颗粒由包裹在薄无定形层中的结晶核组成，该薄无定形层是在颗粒暴露于空气后形成的。我们还报告了FeAl氧化物和碳化物纳米颗粒的合成。所述氧化物纳米颗粒具有顽锌矿FeAl 2 O 4组成，所述碳化物纳米颗粒具有AlFe 3 Co·5组成。尽管结晶的块状FeAI（20-30％重量的Al）材料是非磁性的，但发现类似物纳米粒子甚至在室温以上也具有铁磁性。从室温降至40 K时，观察到几乎与温度无关的大约50 Oe的矫顽力，低于5 K时，矫顽力值在5 K时增加至700 Oe。纳米粒子表现出确定的交换各向异性效应，这可能是由于在20 K时的表面各向异性引起的。这些颗粒上吸附的氧气层。沿着磁场和磁化轴观察到的磁滞回线的位移与施加磁场的方向可逆。 FeAl纳米颗粒可能会导致一种新型形式的先进材料，该材料结合了高电阻率，抗氧化性，延展性和独特的磁性。

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