Ultramicrotomy as a Technique for Materials Specimen Preparation

1990 ◽  
Vol 48 (2) ◽  
pp. 428-429
Author(s):  
S.R. Glanvill
Keyword(s):  
Materials Science ◽  
Structural Information ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Cross Sectional ◽  
Surfaces And Interfaces ◽  
Beam Analysis ◽  
Flat Embedding ◽  
20 Nm ◽  
Sectional Analysis

This paper summarizes the application of ultramicrotomy as a specimen preparation technique for some of the Materials Science applications encountered over the past two years. Specimens 20 nm thick by hundreds of μm lateral dimension are readily prepared for electron beam analysis. Materials examined include metals, plastics, ceramics, superconductors, glassy carbons and semiconductors. We have obtain chemical and structural information from these materials using HRTEM, CBED, EDX and EELS analysis. This technique has enabled cross-sectional analysis of surfaces and interfaces of engineering materials and solid state electronic devices, as well as interdiffusion studies across adjacent layers.Samples are embedded in flat embedding moulds with Epon 812 epoxy resin / Methyl Nadic Anhydride mixture, using DY064 accelerator to promote the reaction. The embedded material is vacuum processed to remove trapped air bubbles, thereby improving the strength and sectioning qualities of the cured block. The resin mixture is cured at 60 °C for a period of 80 hr and left to equilibrate at room temperature.

Applications of ultramicrotomy for materials characterization

1993 ◽  
Vol 51 ◽  
pp. 232-233
Author(s):  
R.T. Blackham ◽  
J.J. Haugh ◽  
C.W. Hughes ◽  
M.G. Burke
Keyword(s):  
Materials Science ◽  
Microstructural Analysis ◽  
Analytical Electron Microscopy ◽  
Austenitic Stainless Steels ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Thermally Induced ◽  
Radiation Induced ◽  
Characterization Of Materials

Essential to the characterization of materials using analytical electron microscopy (AEM) techniques is the specimen itself. Without suitable samples, detailed microstructural analysis is not possible. Ultramicrotomy, or diamond knife sectioning, is a well-known mechanical specimen preparation technique which has been gaining attention in the materials science area. Malis and co-workers and Glanvill have demonstrated the usefulness and applicability of this technique to the study of a wide variety of materials including Al alloys, composites, and semiconductors. Ultramicrotomed specimens have uniform thickness with relatively large electron-transparent areas which are suitable for AEM anaysis.Interface Analysis in Type 316 Austenitic Stainless Steel: STEM-EDS microanalysis of grain boundaries in austenitic stainless steels provides important information concerning the development of Cr-depleted zones which accompany M23C6 precipitation, and documentation of radiation induced segregation (RIS). Conventional methods of TEM sample preparation are suitable for the evaluation of thermally induced segregation, but neutron irradiated samples present a variety of problems in both the preparation and in the AEM analysis, in addition to the handling hazard.

A Technique for Preparing “Two in One” Cross-Sectional TEM Specimens

1990 ◽  
Vol 199 ◽  
Author(s):  
Guang-Hwa M. Ma ◽  
Sopa Chevacharoenkul
Keyword(s):  
Sample Preparation ◽  
The Other ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Preparation Time ◽  
Cross Sectional ◽  
Sample Preparation Technique ◽  
Two Samples ◽  
Junction Formation ◽  
Suitable Marker

ABSTRACTA modified “two-in-one” cross-sectional TEM sample preparation technique is described. By coating a thin layer of “marker” to distinguish one sample from the other, two samples could be simultaneously prepared in one TEM cross-sectional specimen. Therefore, the specimen preparation time is reduced by nearly one half. The coating can be done in an existing ion-mill. Criteria for choosing a suitable marker as well as tips on getting good quality specimens are described. An example of applying this technique to a processing-microstructure study of an ultra-shallow junction formation in silicon is demonstrated.

Preparation of fragile catalyst materials for TEM

1995 ◽  
Vol 53 ◽  
pp. 412-413
Author(s):  
K.L. More ◽  
D.W. Coffey ◽  
T.S. Geer
Keyword(s):  
Spatial Information ◽  
Substrate Surface ◽  
Model Systems ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Cross Sectional ◽  
Process Modification ◽  
Transmission Electron ◽  
Section Technique ◽  
Catalyst Systems

A novel specimen preparation technique for transmission electron microscopy (TEM) has been developed which allows for the preservation of constituent placement within a variety of diesel and automotive catalyst materials. The standard preparation method for imaging catalyst particles and washcoat constituents has been to use powders scraped from the substrate surface. However, while limited imaging of fine scale structures is possible on clean specimens using this method, all cross-sectional spatial information is lost. Thus, scraped powder specimens cannot be used to directly image surface effects in the TEM or to view large areas of "intact" material in these catalyst systems. Also, for many microscopy investigations such as electron energy loss spectroscopy and high resolution imaging, powders can be too thick. Other preparation techniques have also been used, for example ultramicrotomy and model systems, with some limited success. It is clear that by preparing TEM specimens using this cross-section technique, changes in microstructure to either precious metal particles or washcoat constituents with distance from the exposed surface can be evaluated as a function of aging, engine use, or process modification.

Morphological and structural study of integrated circuits using XTEM and HREM

1990 ◽  
Vol 48 (4) ◽  
pp. 630-631
Author(s):  
L.M. Bharadwaj ◽  
L.M. Gantcheva ◽  
S. Simov ◽  
G. Balossier ◽  
J. Faure ◽  
...  
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
Ion Beam ◽  
Etching Rate ◽  
Glass Plate ◽  
Region Of Interest ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Cross Sectional ◽  
Mechanical Preparation

There is increasing interest in the use of cross-sectional transmission electron microscopy (XTEM) to understand fundamental and technological problems associated with fabrication of integrated circuit (IC). This is because with XTEM it is possible to obtain exact morphological configuration and structure at atomic level of different layers and interfaces. For the study of a MOS device we used slightly modified XTEM specimen preparation technique than reported by other authors. To monitor region of interest during mechanical preparation two techniques were used as illustrated in Fig.1. First by glueing two slabs (10 × 4 mm2) of wafer each exactly identical in terms of geometrical dimension and device features and second by glueing a transparent glass plate on the top of wafer. The epoxy has higher ion beam etching rate than other materials so to obtain uniform thinning, ion beam was centered slightly away from the epoxy line . The thinned specimens were observed under Philips CM-30 electron microscope.

Contrast from epitaxially sandwiched macromolecules

1978 ◽  
Vol 36 (2) ◽  
pp. 226-227
Author(s):  
M. Talianker ◽  
D.G. Brandon
Keyword(s):  
Gold Film ◽  
Lattice Defect ◽  
Gold Foil ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Resolution Limit ◽  
Transmission Electron ◽  
Crystal Lattice Defect ◽  
Void Effect ◽  
Lattice Resolution

A new specimen preparation technique for visualizing macromolecules by conventional transmission electron microscopy has been developed. In this technique the biopolymer-molecule is embedded in a thin monocrystalline gold foil. Such embedding can be performed in the following way: the biopolymer is deposited on an epitaxially-grown thin single-crystal gold film. The molecule is then occluded by further epitaxial growth. In such an epitaxial sandwich an occluded molecule is expected to behave as a crystal-lattice defect and give rise to contrast in the electron microscope.The resolution of the method should be limited only by the precision with which the epitaxially grown gold reflects the details of the molecular structure and, in favorable cases, can approach the lattice resolution limit.In order to estimate the strength of the contrast due to the void-effect arising from occlusion of the DNA-molecule in a gold crystal some calculations were performed.

The ionic strength dependence of chromatin folding

1978 ◽  
Vol 36 (2) ◽  
pp. 220-221
Author(s):  
F. Thoma ◽  
TH. Koller
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Ionic Strength ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Carbon Supports ◽  
Ionic Strength Dependence ◽  
Chromatin Folding ◽  
Strength Dependence ◽  
Preparation Techniques

Under a variety of electron microscope specimen preparation techniques different forms of chromatin appearance can be distinguished: beads-on-a-string, a 100 Å nucleofilament, a 250 Å fiber and a compact 300 to 500 Å fiber.Using a standardized specimen preparation technique we wanted to find out whether there is any relation between these different forms of chromatin or not. We show that with increasing ionic strength a chromatin fiber consisting of a row of nucleo- somes progressively folds up into a solenoid-like structure with a diameter of about 300 Å.For the preparation of chromatin for electron microscopy the avoidance of stretching artifacts during adsorption to the carbon supports is of utmost importance. The samples are fixed with 0.1% glutaraldehyde at 4°C for at least 12 hrs. The material was usually examined between 24 and 48 hrs after the onset of fixation.

SEM evaluation of the TEM cold-stage double-film specimen

1984 ◽  
Vol 42 ◽  
pp. 272-273
Author(s):  
Jayesh Bellare
Keyword(s):  
Spatial Distribution ◽  
Sample Preparation ◽  
Sample Thickness ◽  
Specimen Preparation ◽  
Preparation Technique ◽  
Liquid Sample ◽  
Thin Specimen ◽  
Sample Preparation Technique ◽  
Cold Stage ◽  
Film Specimen

Seeing is believing, but only after the sample preparation technique has received a systematic study and a full record is made of the treatment the sample gets.For microstructured liquids and suspensions, fast-freeze thermal fixation and cold-stage microscopy is perhaps the least artifact-laden technique. In the double-film specimen preparation technique, a layer of liquid sample is trapped between 100- and 400-mesh polymer (polyimide, PI) coated grids. Blotting against filter paper drains excess liquid and provides a thin specimen, which is fast-frozen by plunging into liquid nitrogen. This frozen sandwich (Fig. 1) is mounted in a cooling holder and viewed in TEM.Though extremely promising for visualization of liquid microstructures, this double-film technique suffers from a) ireproducibility and nonuniformity of sample thickness, b) low yield of imageable grid squares and c) nonuniform spatial distribution of particulates, which results in fewer being imaged.

Preparation of cross-sectional samples for near-surface TEM studies

1987 ◽  
Vol 45 ◽  
pp. 380-381
Author(s):  
R.C. Dickenson ◽  
K.R. Lawless
Keyword(s):  
Standard Sample ◽  
Surface Region ◽  
Specimen Preparation ◽  
Thick Sheet ◽  
Drill Bit ◽  
Sample Holder ◽  
Metal Interface ◽  
Cross Sectional ◽  
Near Surface ◽  
Cold Worked

In thermal oxidation studies, the structure of the oxide-metal interface and the near-surface region is of great importance. A technique has been developed for constructing cross-sectional samples of oxidized aluminum alloys, which reveal these regions. The specimen preparation procedure is as follows: An ultra-sonic drill is used to cut a 3mm diameter disc from a 1.0mm thick sheet of the material. The disc is mounted on a brass block with low-melting wax, and a 1.0mm hole is drilled in the disc using a #60 drill bit. The drill is positioned so that the edge of the hole is tangent to the center of the disc (Fig. 1) . The disc is removed from the mount and cleaned with acetone to remove any traces of wax. To remove the cold-worked layer from the surface of the hole, the disc is placed in a standard sample holder for a Tenupol electropolisher so that the hole is in the center of the area to be polished.

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