X-ray absorption and diffraction studies of thin polymer/FePt nanoparticle assemblies
X-ray absorption and diffraction studies of thin polymer/FePt nanoparticle assemblies
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DOI：
10.1063/1.1567802
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发表时间：
2003-05-15
影响因子：
3.2
通讯作者：
Murray, CB
中科院分区：
文献类型：
--
作者：
Anders, S;Toney, MF;Murray, CB
我们在室温下使用聚合物介导的逐层沉积生产了单分散 4 nm FePt 纳米粒子的组件。该过程可以很好地控制颗粒组装厚度，并为未来超高密度磁存储介质的制造提供巨大潜力。应用磁场高达 9 T 的振动样品磁力测定法来研究颗粒集合体的磁性随退火条件的变化，同时使用近边缘 X 射线吸收精细结构 (NEXAFS) 光谱和 X 射线衍射 (XRD) 来研究颗粒内的化学性质和结构特性。研究发现，在 800 ℃ 下退火的样品的矫顽力可高达 22.7 kOe，在 650 ℃ 下退火的样品的矩密度（归一化为颗粒体积）估计接近于块状 FePt 的值（1140 emu/cm3）。 NEXAFS 光谱表明沉积态组件中的 Fe 部分被氧化，并且通过退火大大减少了氧化。对高温退火组件的 XRD 研究揭示了原子有序度的增加以及颗粒内高各向异性 L1(0) 相的形成。然而，高温退火也导致纳米颗粒团聚。 (C) 2003 年美国物理研究所。
We have produced assemblies of monodisperse 4 nm FePt nanoparticles using polymer-mediated layer-by-layer deposition at room temperature. The process leads to good control of particle assembly thickness and offers great potential for future fabrication of ultra-high density magnetic storage media. Vibrating sample magnetometry with fields up to 9 T was applied to study the magnetic properties of the particle assemblies as a function of annealing condition while near edge x-ray absorption fine structure (NEXAFS) spectroscopy and x-ray diffraction (XRD) were used to investigate the chemical nature and structural properties within particles. It was found that the coercivity can be as high as 22.7 kOe for samples annealed at 800 degreesC, the moment density (normalized to the particle volume) for the sample annealed at 650 degreesC is estimated close to the value for bulk FePt, at 1140 emu/cm3. NEXAFS spectroscopy shows that the Fe in the as-deposited assemblies is partly oxidized, and the oxidation is greatly reduced by annealing. XRD studies on the assemblies annealed at high temperature revealed the increased atomic order and the formation of the high-anisotropy L1(0) phase within the particles. However, the high-temperature annealing also resulted in nanoparticle agglomeration. (C) 2003 American Institute of Physics.