Comparison of Performance of an Analytical Electron Microscope at 300 and 100 kV

1984 ◽  
Vol 41 ◽  
Author(s):  
J. Bentley ◽  
E. A. Kenik ◽  
P. Angelini ◽  
A. T. Fisher ◽  
P. S. Sklad ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Materials Science ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
X Ray ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Convergent Beam ◽  
Electron Energy Loss

AbstractPreliminary results on the performance of an analytical electron microscope (AEM) operating at 300 kV have been obtained and compared with the performance at 100 kV. Some features of the anticipated improvements for transmission electron microscopy (TEM) imaging, convergent beam electron diffraction (CBED), energy dispersive X-ray spectroscopy (EDS), and electron energy loss spectroscopy (EELS) have been studied from the aspect of materials science applications. The electron microscope used was a Philips EM430T operated with a LaB6 cathode and equipped with EDAX 9100/70 EDS and Gatan 607 EELS systems.

A library of convergent-beam electron diffraction patterns

1986 ◽  
Vol 44 ◽  
pp. 688-691
Author(s):  
John F. Mansfield
Keyword(s):  
Electron Diffraction ◽  
Materials Science ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Transmission Electron ◽  
Yield Information ◽  
Analytical Electron ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Electron Energy Loss

One of the most important advancements of the transmission electron microscopy (TEM) in recent years has been the development of the analytical electron microscope (AEM). The microanalytical capabilities of AEMs are based on the three major techniques that have been refined in the last decade or so, namely, Convergent Beam Electron Diffraction (CBED), X-ray Energy Dispersive Spectroscopy (XEDS) and Electron Energy Loss Spectroscopy (EELS). Each of these techniques can yield information on the specimen under study that is not obtainable by any other means. However, it is when they are used in concert that they are most powerful. The application of CBED in materials science is not restricted to microanalysis. However, this is the area where it is most frequently employed. It is used specifically to the identification of the lattice-type, point and space group of phases present within a sample. The addition of chemical/elemental information from XEDS or EELS spectra to the diffraction data usually allows unique identification of a phase.

scholarly journals Materials science applications of a 120kV FEG TEM/STEM: Triskaidekaphilia

1991 ◽  
Vol 49 ◽  
pp. 698-699
Author(s):  
J. Bentley ◽  
A. T. Fisher ◽  
E. A. Kenik ◽  
Z. L. Wang
Keyword(s):  
Electron Microscope ◽  
Materials Science ◽  
X Ray ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Scanning Transmission ◽  
Potential Impact ◽  
Electron Microscopes ◽  
Electron Energy Loss

The introduction by several manufacturers of 200kV transmission electron microscopes (TEM) equipped with field emission guns affords the opportunity to assess their potential impact on materials science by examining applications of similar 100-120kV instruments that have been in use for more than a decade. This summary is based on results from a Philips EM400T/FEG configured as an analytical electron microscope (AEM) with a 6585 scanning transmission (STEM) unit, ED AX 9100/70 or 9900 energy dispersive X-ray spectroscopy (EDS) systems, and Gatan 607 serial- or 666 parallel-detection electron energy-loss spectrometers (EELS). Examples in four areas that illustrate applications that are impossible or so difficult as to be impracticable with conventional thermionic electron guns are described below.

Dislocations in YBa2Cu3O7−δ (δ = 0.77)

1990 ◽  
Vol 48 (4) ◽  
pp. 72-73
Author(s):  
Yimei Zhu ◽  
Hong Zhang ◽  
A.R. Moodenbaugh ◽  
M. Suenaga
Keyword(s):  
Electron Microscope ◽  
Electron Diffraction ◽  
Displacement Vector ◽  
Stacking Faults ◽  
Spot Size ◽  
Convergent Beam Electron Diffraction ◽  
Burgers Vector ◽  
Beam Electron ◽  
X Ray ◽  
Convergent Beam

Abundant dislocations and dislocations associated with stacking faults were observed and characterized in YBa2Cu3O7−δ (δ= 0.77). The crystallographic orientation of the dislocation and the fault were analyzed using Kikuchi patterns matched with computer generated Kikuchi maps. The Burgers vector of the dislocation and the displacement vector of the fault were determined by using the g·b = 0 and g · R=0 criteria.Bulk samples of YBa2Cu3O7 were produced by standard pressing and sintering up to 970 °C. Samples were heated in air, then quenched into liquid nitrogen to reduce oxygen content. Subsequent anneal at 200 ° C took place with samples sealed in silica with 1/2 atm. of argon. TEM specimens were thinned by ion mill and examined in a JEOL 2000FX electron microscope operating at 200kv.X-ray powder diffraction and convergent beam electron diffraction with 200 Å spot size show that YBa2Cu3O6.23 has a tetragonal structure.

Measurement of Debye-Waller factors of silicon as a function of temperature using energy-filtered CBED rocking-curve technique

1994 ◽  
Vol 52 ◽  
pp. 996-997
Author(s):  
S. Swaminathan ◽  
S. Altynov ◽  
I. P. Jones ◽  
N. J. Zaluzec ◽  
D. M. Maher ◽  
...  
Keyword(s):  
Electron Diffraction ◽  
Liquid Nitrogen Temperature ◽  
Convergent Beam Electron Diffraction ◽  
Higher Order ◽  
X Ray Diffraction ◽  
Beam Electron ◽  
X Ray ◽  
Crystal Potential ◽  
Transmission Electron ◽  
Convergent Beam

The advantages of quantitative Convergent Beam Electron Diffraction (CBED) method for x-ray structure factor determination have been reviewed by Spence. The CBED method requires accurate values of Debye-Waller (D-W) factors for the estimation of the coefficients of crystal potential of the higher order beams, Vg, the calculation of the absorption potential, V′g using the Einstein model for phonons, and finally the conversion of the fitted values of the coefficients of crystal potential, V″, to x-ray structure factors. Debye-Waller factors are conventionally determined by neutron or x-ray diffraction methods. Because of the difficulties in conducting high temperature neutron and x-ray diffraction experiments, D-W factors are rarely measured at temperatures above room temperature. Debye-Waller factors at high temperatures can be determined by Convergent Beam Electron diffraction (CBED) method using Transmission Electron Microscopy (TEM) employed with a hot stage attachment. Recently Holmestad et al. have attempted to measure the D-W factors by matching the energy-filtered Higher Order Laue Zone (HOLZ) line intensities near liquid nitrogen temperature.

Advantages of FE-TEM for convergent-beam electron diffraction

1993 ◽  
Vol 51 ◽  
pp. 1206-1207
Author(s):  
T. Kaneyama ◽  
T. Tomita ◽  
Y. Ishida ◽  
M. Kersker
Keyword(s):  
Electron Diffraction ◽  
Spatial Resolution ◽  
Convergent Beam Electron Diffraction ◽  
Lens System ◽  
Beam Electron ◽  
X Ray ◽  
Small Probe ◽  
Electron Microscopes ◽  
Convergent Beam ◽  
Electron Energy Loss

Many electron microscopes equipped with a field-emission gun (FE-TEMs) are now used for the purpose of improving the spatial and the energy resolution in energy dispersive x-ray spectroscopy and electron energy loss spectroscopy. For the convergent-beam electron diffraction techniques, FE-TEMs have greater advantages than conventional electron microscopes with a thermal LaB cathode. We discussed these advantages using JEM2010F and JEM2010, which have equivalent specifications except for the electron source and the condenser lens system.High spatial resolutionThe brightness of an FE-gun (∽ 5 × 108A cm-2 sr-1) is about 100 times that a conventional LaB6 cathode. The gun can obtain enough current for taking CBED patterns in an exposure time of a few seconds even with an electron probe less than 1 nm in diameter (FIG. 1). Steep wedge shapes and rapid bends within the illuminated area deteriorate the accuracy of quantitative CBED analysis. Improvement of the spatial resolution by a small probe reduces these inevitable averaging effects.

Some practical aspects of CBED applications in materials science

1989 ◽  
Vol 47 ◽  
pp. 508-509
Author(s):  
D. R. Liu ◽  
D. B. Williams
Keyword(s):  
Materials Science ◽  
Theoretical Foundation ◽  
Point Group ◽  
Convergent Beam Electron Diffraction ◽  
Zone Axis ◽  
X Ray ◽  
Unambiguous Determination ◽  
Convergent Beam ◽  
Electron Energy Loss

The paper by Buxton et al. has firmly laid down the theoretical foundation for the point group determination of a crystal structure with convergent beam electron diffraction (CBED). Numerous examples of successful applications of this theory to materials science problems have been published. However, it has also been observed that, for an unambiguous determination of some crystal structures, more zone axis CBED patterns are needed than it is indicated by the tables in the paper. Yet sometimes ambiguity can still exist as in the case of the point group determination of the MgAl2O4 spinel, where CBED is unable to detect an alleged Al3+ ion displacement of Δb=0.0002∼0.0006 nm along a <111> direction and thus unable to determine whether its point group should be m3m or m. This difficulty might be attributed to the fact that, as for microanalysis, such as x-ray energy dispersive spectroscopy and electron energy-loss spectroscopy, the CBED technique must have its detection limit beyond which the detail in an acquired CBED pattern is not adequate enough to permit an unambiguous determination of its diffraction group.

The Analysis of Particles With Energy Dispersive X-Ray Spectroscopy (EDS)

1998 ◽  
Vol 4 (S2) ◽  
pp. 184-185
Author(s):  
J. A. Small ◽  
J. A. Armstrong ◽  
D. S. Bright ◽  
B. B. Thorne
Keyword(s):  
Electron Microscope ◽  
Elemental Analysis ◽  
Electron Probe ◽  
Initial Particle ◽  
X Ray ◽  
Transmission Electron ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
The Individual ◽  
Individual Particles

The addition of the Si-Li detector to the electron probe, the scanning electron microscope, and more recently the transmission electron microscope (resulting in the analytical electron microscope) has made it possible to obtain elemental analysis on individual “particles” with dimensions less than 1 nm using EDS. Although some initial particle studies on micrometer-sized particles were done on the electron probe using wavelength dispersive spectrometers, WDS, the variability and complexity of many particle compositions coupled with the high currents necessary for WDS made elemental analysis of particles by WDS difficult at best. In addition, the use of multiple spectrometers, each with a different view of the particle and therefore different particle geometry as shown in Fig. 1, limited the quantitative capabilities of the technique. With the introduction of the Si-Li detector, there was only one spectrometer with a single geometry resulting in the development of various procedures for obtaining quantitative elemental analysis of the individual particles.

Combined elemental and structural imaging in a computer contrlled analytical electron microscope

1983 ◽  
Vol 41 ◽  
pp. 10-13
Author(s):  
R. D. Leapman ◽  
C. E. Fiori ◽  
K. E. Gorlen ◽  
C. C. Gibson ◽  
C. R. Swyt
Keyword(s):  
Electron Microscope ◽  
Computer Hardware ◽  
X Ray ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Scanning Transmission ◽  
Northern Side ◽  
Electron Energy Loss ◽  
Modern Analytical ◽  
Digital Equipment

The modern analytical electron microscope incorporates a scanning transmission (STEM) capability together with a variety of detectors for signals resulting from the interaction of the electron probe with the sample. Information about both the elemental composition and morphology of the sample is available. The images derived from STEM signals can be readily digitized, thus allowing precise numerical processing of the data. Since several signals may be recorded concurrently one pixel at at time, the corresponding images are in registration and may be overlaid for comparison or combined for example to give the ratio of two elements. Such composite images can be expected to provide more information than each separately.The large amount of data which has to be processed in the acquisition of a digitized image requires a considerable amount of computer hardware and software. The system developed at NIH for application in biology has been described by Gorlen et al. and Fiori et al. and is outlined in Fig. 1. A Digital Equipment Corporation PDP 11/60 computer with an LSI 11/23 satellite computer is interfaced to a Hitachi H700H TEM-STEM with a magnetic sector electron energy loss spectrometer (EELS), one Kevex top-looking energy dispersive x-ray detector and one Tracor Northern side-looking detector; these provide the analytical signals with digital output.

Elemental Mapping by Core Level Excitations in the Analytical Electron Microscope

1987 ◽  
Vol 45 ◽  
pp. 192-195
Author(s):  
R.D. Leapman
Keyword(s):  
Electron Microscope ◽  
Fluorescence Yield ◽  
Core Level ◽  
Limiting Factor ◽  
X Ray ◽  
Probe Diameter ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Counting Statistics ◽  
Electron Energy Loss

Elemental distributions can be obtained in the analytical electron microscope by detecting core level excitations resulting from interaction of the scanned electron beam with atoms in the sample. This core level signal is recorded either through inelastic scattering measured by electron energy loss spectroscopy (EELS) or through x-ray emission measured by energy dispersive x-ray spectroscopy (EDXS). EELS is well suited to analysis of light elements for which the fluorescence yield is low whereas EDXS is sensitive to heavier elements; for several elements the two methods are competitive. The spatial resolution can approach the probe diameter, typically 1 to 50 nm, provided (i) the sample is thin enough to limit beam spreading effects, (ii) the counting statistics are adequate to detect a particular element, (iii) radiation damage is not a limiting factor, and (iv) delocalization of the scattering events is smaller than the probe diameter (in the case of high resolution studies).

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