Preparation of location-specific thin foils from Fe–3% Si bi- and tri-crystals for examination in a FEG-STEM

Bi-crystals and tri-crystals of a nominal Fe–3% Si (wt%) of well-defined orientations have been grown using a floating-zone technique with optical heating. The manufacture of these unique crystals and the preparation technique involved in harvesting thin foils from specific locations for transmission electron microscopy are described in detail. In particular, the grain boundary triple junction has been extracted from the tri-crystal and examined in high-resolution aberration-corrected FEG-STEM instruments. To achieve the necessary resolution, the foils have to be uniformly thin, in the range 50–100 nm over large areas of the specimen. For ferromagnetic materials, there are further challenges arising from the magnetic field interaction, with the electron beam placing significant demands on the aberration correction system. One way to minimise this interaction is to reduce the total mass of magnetic material. To achieve this, an in situ focused ion beam lift-out technique has been combined with an additional precision ion-polishing stage to reproducibly provide thin-foil specimens suitable for high-resolution EELS and EDX analysis. Examination of the foils reveals that the final precision ion-polishing stage removes residual damage arising from the use of focused ion beam milling procedures.     

Nb3Si对Nb-18Si原位复合材料微观组织的影响

用真空电弧熔炼方法制备了处于共晶区的Nb 18Si复合材料,用背散射电子相(BEI)和X射线衍射(XRD)分析了铸态和1 200℃×100h退火后复合材料的微观组织形貌和相组成,并进行了断口形貌分析.结果发现退火可以促进亚稳定相Nb3Si分解成Nb5Si3+Nb.延性相Nbss粒子尺寸和体积分数的增加影响材料的断口形貌,铸态的断口完全呈解理断裂,退火以后断口中出现界面脱离.脆性相对延性相的约束程度对材料的韧性影响很大.     

A comparison of EDS microanalysis in FIB-prepared and electropolished TEM thin foils

This paper reports the results of a fine-probe EDS microanalytical study of cellular precipitation in a Cu-Ti binary alloy. Compositional profiles across the solute depleted Cu-rich FCC lamellae and the Cu4Ti lamellae within isothermally formed cellular colonies were measured in a FEG-TEM from thin-foil specimens prepared by conventional electropolishing and by a technique using a Ga+ focused ion-beam (FIB). The Cliff-Lorimer ratio method, with an absorption correction, was employed to quantify the compositions. Two FIB samples were prepared with different orientations of the lamellae with respect to the ion-milling direction. The compositional profiles across the Cu-rich FCC lamellae and the Cu4Ti compound lamellae in both the FIB-prepared samples and the electropolished sample were, within experimental error, numerically equivalent. The composition of the Cu4Ti compound phase lamellae was very close to the ideal stoichiometric composition of 20 at % Ti. It is concluded that for this system, and for the specimen preparation procedures used in this study, the Ga+ ion-milling process has had no detectable effect on the chemistry changes across the interlamellar interface at the scale studied. These results indicate that the possible sources of chemical artifacts which include redeposition, preferential sputtering and ion-induced atomic migration can be minimized if several precautions are taken during milling in the FIB. Consistent with previous investigators, it was also found that the ion-milling process does introduce significant structural artifacts (e.g., dislocations) into the softer FCC Cu-rich phase compared with a specimen produced by conventional electropolishing.     

新方法制备透射电镜粉末样品

尝试一种新的方法制备了SiC粉末的透射电镜样品,并利用H－800型透射电子显微镜对SiC粉末样品进行了观察。     

Preparation of ultrathin polyethylene foils by film casting

A procedure for making normal and deuterated polyethylene foils with a thickness of 0.02 to 2 mum by the film casting method is described. The thickness of the foils is controlled by the concentration and temperature of the solution, and the quality is determined by the uniformity of temperature and rate of solution drainage.     

Preparation of damage-free glass TEM specimens

A jet polishing technique to chemically thin glass specimens for transmission electron microscopy (TEM) after a preliminary mechanical dimpling step has been developed. Slightly modified commercial equipment is used with automatic optical termination of the polishing process to produce foils exhibiting large, high quality, electron transparent regions.     

Prerequisites for a Cc/Cs-corrected ultrahigh-resolution TEM

After the introduction of a corrector to compensate for the spherical aberration of a TEM and the acceptance of this new instrumentation for high-resolution CTEM (conventional transmission electron microscope) and STEM (scanning transmission electron microscope) by the electron microscopy community, a demand for even higher resolution far below 1A has emerged. As a consequence several projects around the world have been launched to make these new instruments available and to further push the resolution limits down toward fractions of 1A. For this purpose the so-called TEAM (transmission electron aberration-corrected microscope) has been initiated and is currently under development. With the present paper we give a detailed assessment of the stability required for the base instrument and the electric stability, the manufacturing precision, and feasible semi-automatic alignment procedures for a novel C(c)/C(s)-corrector in order to achieve aberration-free imaging with an information limit of 0.5A at an acceleration voltage of 200 kV according to the goals for the first TEAM instrument. This new aberration corrector, a so-called Achroplanat, in combination with a very stable high-resolution TEM leads to an imaging device with unprecedented resolving power and imaging properties.     

Preparation of TEM samples for hard ceramic powders

It is challenging to prepare a good sample for high-resolution electron microscopy of polycrystalline ceramic powders containing hard particles or particles with a strong preferential cleavage. Here we demonstrate that embedding the particles in a Cu matrix in a pressed pellet allows for straightforward conventional ion milling. The method is applied to powders of Mg10Ir19B16 and Na0.5CoO2 to show its feasibility, whereby transmission electron microscopy (TEM) samples with crystalline areas thinner than 10 nm can be obtained easily.     

Preparation of carbon-free TEM microgrids by metal sputtering

A new method for preparing carbon-free, temperature-stable Transmission Electron Microscope (TEM) grids is presented. An 80% Au/20% Pd metal film is deposited onto a ‘holey’ microgrid carbon supported on standard mixed-mesh Au TEM grids. Subsequently, the carbon film is selectively removed using plasma cleaning. In this way, an all-metal TEM film is made containing the ‘same’ microgrid as the original carbon film. Although electron transparency of the foil is reduced significantly, the open areas for TEM inspection of material over these areas are maintained. The metal foil can be prepared with various thicknesses and ensures good electrical conductivity. The new Au/Pd grids are stable to at least 775 K under vacuum conditions.     

TEM纳米尺度石墨标样的制备

透射电镜的长度标尺或公称放大倍数是判断试样中组织细节尺寸的依据,需要应用纳米级长度标样进行校准。本文介绍了一种用石墨制备透射电镜专用纳米尺度标样的方法,对石墨的X射线衍射分析以及对石墨标样的TEM高分辨像和电子衍射分析表明,标样中石墨的高分辨像为（002）晶面的点阵像,其晶面间距为0．342nm,可作为纳米尺度的参照材料。本文对使用纳米尺度标样校正ETEM标尺的基本方法进行了简要讨论。     

Preparation of thin ceramic monofilaments for characterization by TEM

A method for preparing transmission electron microscopy specimens from ceramic fibers has been developed that is particularly useful when only a small amount of the material is available for characterization. Fiber segments are lined up and sandwiched between two glass slides using high-temperature epoxy. The resulting specimen is then polished flat from both sides using tripod polisher to remove the glass and produce thin (< 2 microm) longitudinal section of the fibers. The specimen is then ion-milled for a short time to produce electron-transparent areas. The method is also suitable for preparing very flat specimens for site-specific optical and SEM analysis.     

导电纳米材料及非导电纳米材料的透射电镜薄样制备

介绍导电纳米材料及非导电纳米材料块状样品的透射电镜薄样制备技术，对薄样的制备程序及要点作了阐述，分析了非导电纳米材料在TEM下观察时产生样品荷电漂移现象的原因，并对防止非导电纳米材料荷电漂移的薄样制备方法作了分析和说明。     

Imaging a dense nanodot assembly by phase retrieval from TEM images

Phase retrieval is a classical inverse problem in many fields dealing with waves that is becoming of increasing interest in transmission electron microscopy (TEM). A non-interferometric approach is here applied to TEM images. Phase retrieval possibilities given by the transport intensity equation are compared to the ones deriving from the weak phase object approximation. In the limit of small angles, both methods lead to a similar equation between the phase and a set of defocus images. This equation can be solved by an image processing equivalent to using a specific filter in Fourier space. This processing leads to phase images with a spatial resolution here essentially limited by the defocus amount between images. A dense assembly of silicon nanodots is used as a model case to illustrate the interest of this approximate phase retrieval method which can be carried out on standard equipment. The dot heights estimated using the phase images are found to be in good agreement with ones measured by atomic force microscopy. Since image noise and large defocus values may strongly affect the solution given by the approximate method, an iterative phase retrieval method is also used as a test for working conditions.     

Development of a quantitative energy filtering TEM method to study a reactive NiO/80Ni20Fe interface.

Energy filtering TEM (EFTEM) has been performed on an annealed NiO/80Ni20Fe interface. Chemical maps have been calculated using the three-window technique on the O-K, Fe-L23 and Ni-L23 edges. In this paper we show that relative quantification can be made using reference areas on the images taken from part to part of the interface in well-known composition areas. Partial cross-section ratios sigmaNi(20 eV)/sigmaO(20 eV) and sigmaNi(20 eV)/sigmaFe(20 eV) have been then measured and used to extract the chemical composition of the reactive NiO/80Ni20Fe interface. Fe, Ni and O composition profiles across the interface have been obtained showing the diffusion process which has occurred during annealing. The reliability of the EFTEM measurements has been checked by EEL spectroscopy on the same sample as well as on a reference geological oxide sample (Trevorit: NiFe2O4). The partial cross-section ratios obtained with the two methods (EFTEM and EELS) are in good agreement.     

Preparation of (InGa)As/GaAs materials for TEM by one side non-rotation ion beam thinning

A technique is described for the preparation of thin specimens for transmission electron microscopy (TEM) of (InGa)As/GaAs multilayered materials. In this technique, a shielding method is used for selective-area perforation by ion beam thinning. Thin cross-sectional specimen slices are mechanically pre-thinned to about 30 μm and then thinned by ion sputtering from one side of the specimen at a time without rotation of the specimen stage. No direct ion sputtering occurs at the growth surface of the specimen so that a specimen with thin areas containing the desired near-surface structures can be obtained. The recipe for this technique is given in detail. A patterning method for increasing the size of the thin area for TEM investigation is also described. It is shown that a smooth surface can be obtained by sputtering without rotating the stage if obstacles that produce redeposits onto the sputtered surface are removed.     

Synthesis of fully rotatable R-S-S-R linkagesCинтeз кpивoшипнoгo B-C-C-B pычaжнoгo мeнизмa

Algebraic-geometrical techniques to design fully rotatable R-S-S-R linkages with transmission angle control are presented. The concept of upper bounding Cos μ where μ is the transmission angle, is used to obtain feasible regions for linkages with full input-link rotatability. The proposed feasible regions have algebraic boundaries. This concept was developed earlier for the precision synthesis of planar four-bar linkage and it has now been extended to the precision synthesis of R-S-S-R linkage.     

水热制备纳米AlOOH晶须条件控制形貌TEM分析

本论文针对水热制备纳米AlOOH晶须的条件控制做了较为全面的探索,以盐酸、铝酸钠为原材料,通过添加单组分多组分添加剂,考察了温度、时间,以及加转子磁振动等试验方式对晶须形貌的影响,探索适宜的AlOOH晶须制备奈件优化组合通过透射电镜分析检测其形貌特征,长度及直径大小,通过XRD衍射分析,总结出AlOOH定向结晶的一般习性,在综合各种样品的形貌特点的基础上,进一步探索制备形貌较好的AlOOH晶须的优化工艺方法.     

Preparation of thin ceramic monofilaments for TEM observation with novel embedding processes

An applicable method to prepare transmission electron microscopy specimens from ceramic fibers for longitudinal and cross-sectional observations is investigated. The method includes novel embedding processes to fix fibers, a polishing process using a self-manufactured device to get uniformly low thickness (40 μm for L-fiber, 60 μm for C-fiber), a one-side dimpling process to grind the specimen to near electron transparency (about 5 μm in thickness for both L-fiber and C-fiber) and an efficient ion milling process using calculated parameters. These techniques are reliable to accomplish the preparation with high quality in a relatively short time. Many factors related to the preparation processes are discussed.     

Manufacture of some SIMS components from tantalum foils by electrolytic photoetching

Components of a specimen holder used in secondary ion mass spectrometry (SIMS) have been fabricated from tantalum by electrolytic photoetching. Principal benefits of the technique are the ability to use a non-hazardous etchant and the ease with which design modifications can be carried out