Preparation of high‐quality ultrathin transmission electron microscopy specimens of a nanocrystalline metallic powder
Preparation of high‐quality ultrathin transmission electron microscopy specimens of a nanocrystalline metallic powder
复制标题
DOI：
10.1002/jemt.21116
复制
发表时间：
2012-06
影响因子：
2.5
通讯作者：
T. Riedl;T. Gemming;C. Mickel;K. Eymann;A. Kirchner;B. Kieback
中科院分区：
文献类型：
--
作者：
T. Riedl;T. Gemming;C. Mickel;K. Eymann;A. Kirchner;B. Kieback
本文以高强度纳米晶铜-Nb粉末合金为例，探讨了三种不同的制备方法对样品厚度和质量的影响。对于纳米晶体材料中的颗粒的空间分辨分析，低样品厚度是必不可少的。我们发现，镶嵌在环氧树脂中的铜-Nb粉末的单面和双面小角度Ar离子球磨在边缘附近产生了厚度很小(<；10 nm)的楔形颗粒。利用一种改进的聚焦离子束提拉技术，在薄片内部获得了大的微米级电子透明区。然而，该薄层在≥30 nm的边缘处显示出较高的厚度。讨论了离子损伤深度、后向散射和表面粗糙度等对观察到的厚度的限制因素，这些因素取决于离子类型、能量、电流密度和样品运动。最后，用超微切割法在低笔划率和低固定厚度下切割的切片提供了巨大的、几十平方微米的均匀薄的∼10 nm最小厚度的区域。作为主要的缺点，我们已经检测到由作为包埋材料的环氧树脂组成的截面上的薄涂层以及相当大的纳米级厚度变化。Microsc.技术资源。2012年，75：711-719。©2011 Wiley期刊，Inc.
This article explores the achievable transmission electron microscopy specimen thickness and quality by using three different preparation methods in the case of a high‐strength nanocrystalline Cu–Nb powder alloy. Low specimen thickness is essential for spatially resolved analyses of the grains in nanocrystalline materials. We have found that single‐sided as well as double‐sided low‐angle Ar ion milling of the Cu–Nb powders embedded into epoxy resin produced wedge‐shaped particles of very low thickness (<10 nm) near the edge. By means of a modified focused ion beam lift‐out technique generating holes in the lamella interior large micrometer‐sized electron‐transparent regions were obtained. However, this lamella displayed a higher thickness at the rim of ≥30 nm. Limiting factors for the observed thicknesses are discussed including ion damage depths, backscattering, and surface roughness, which depend on ion type, energy, current density, and specimen motion. Finally, sections cut by ultramicrotomy at low stroke rate and low set thickness offered vast, several tens of square micrometers uniformly thin regions of ∼10‐nm minimum thickness. As major drawbacks, we have detected a thin coating on the sections consisting of epoxy deployed as the embedding material and considerable nanoscale thickness variations. Microsc. Res. Tech. 75:711–719, 2012. © 2011 Wiley Periodicals, Inc.