Layer resolved structural relaxation at the surface of magnetic FePt icosahedral nanoparticles
Layer resolved structural relaxation at the surface of magnetic FePt icosahedral nanoparticles
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磁性 FePt 二十面体纳米颗粒表面的层解析结构弛豫
DOI：
10.1103/physrevlett.100.017205
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发表时间：
2008-01-11
影响因子：
8.6
通讯作者：
Kisielowski, C.
中科院分区：
文献类型：
--
作者：
Wang, R. M.;Dmitrieva, O.;Kisielowski, C.
采用亚角分辨率焦系重建的高分辨透射电子显微镜定量研究了二十面体结构的金属FePT纳米粒子的周期性壳层结构和表面重建。真空气相凝聚法制备的二十面体FePT纳米粒子在电子束辐照下具有惊人的抗氧化性和稳定性。我们发现，表面区(111)晶面的晶格间距与尺寸有关，相对于Fe(52)、Pt(48)的体积值，晶格间距膨胀高达9%。原位控制去除(111)表面层会导致新表面层类似的向外松弛。讨论了这种异常大的层向向外弛豫，即铂在富铁的Fe/铂核周围形成富铂壳的表面上的优先偏析。
The periodic shell structure and surface reconstruction of metallic FePt nanoparticles with icosahedral structure has been quantitatively studied by high-resolution transmission electron microscopy with focal series reconstruction with sub-angstrom resolution. The icosahedral FePt nanoparticles fabricated by the gas phase condensation technique in vacuum have been found to be surprisingly oxidation resistant and stable under electron beam irradiation. We find the lattice spacing of (111) planes in the surface region to be size dependent and to expand by as much as 9% with respect to the bulk value of Fe(52)Pt(48). Controlled removal of the (111) surface layers in situ results in a similar outward relaxation of the new surface layer. This unusually large layerwise outward relaxation is discussed in terms of preferential Pt segregation to the surface forming a Pt enriched shell around a Fe-rich Fe/Pt core.