Aspects of microanalysis in a transmission electron microscope

1978 ◽  
Vol 36 (1) ◽  
pp. 510-511
Author(s):  
R. Sinclair ◽  
B.E. Jacobson
Keyword(s):  
Grain Size ◽  
Electron Beam ◽  
Electron Microscope ◽  
Chemical Analysis ◽  
Transmission Electron Microscope ◽  
Vapor Deposition ◽  
Critical Currents ◽  
X Ray ◽  
Fine Grain ◽  
Transmission Electron

INTRODUCTIONThe prospect of performing chemical analysis of thin specimens at any desired level of resolution is particularly appealing to the materials scientist. Commercial TEM-based systems are now available which virtually provide this capability. The purpose of this contribution is to illustrate its application to problems which would have been intractable until recently, pointing out some current limitations.X-RAY ANALYSISIn an attempt to fabricate superconducting materials with high critical currents and temperature, thin Nb3Sn films have been prepared by electron beam vapor deposition [1]. Fine-grain size material is desirable which may be achieved by codeposition with small amounts of Al2O3 . Figure 1 shows the STEM microstructure, with large (∽ 200 Å dia) voids present at the grain boundaries. Higher quality TEM micrographs (e.g. fig. 2) reveal the presence of small voids within the grains which are absent in pure Nb3Sn prepared under identical conditions. The X-ray spectrum from large (∽ lμ dia) or small (∽100 Ǻ dia) areas within the grains indicates only small amounts of A1 (fig.3).

Reaction Layer Microstructure of SiC/SiC Joints Brazed by Ag-Cu-Ti Filler Metal

2010 ◽  
Vol 434-435 ◽  
pp. 202-204 ◽  
Author(s):  
Yan Liu ◽  
Zheng Ren Huang ◽  
Xiu Jian Liu
Keyword(s):  
Grain Size ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Reaction Layer ◽  
Filler Metal ◽  
Growth Behavior ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Electronic Probe

Abstract. The reaction layer microstructure of SiC/SiC joints brazed by Ag-Cu-Ti filler metal, including composition, morphology, grain size were investigated by X-ray diffraction, electronic probe microanalysis, transmission electron microscope. An obvious reaction layer composed of TiC and Ti5Si3 was observed at the interface of SiC substrate and filler metal. There is a representative structure of SiC substrate/continuous fine TiC layer /discontinuous coarse Ti5Si3 layer/filler metal in the reaction layer. The continuous TiC layer, composed of about 10 nm roundish grains, is 350 ~ 400 nm thick. Ti5Si3 layer is composed of only one row of Ti5Si3 grains, which disperse with diverse size from 100 ~ 500 nm. Different growth behavior of TiC and Ti5Si3 is the main reason to form this microstructure.

Quantitative Elemental Analysis of “Transparent” Particles in the Tem

1976 ◽  
Vol 34 ◽  
pp. 416-417
Author(s):  
J. W. Sprys ◽  
M. A. Short
Keyword(s):  
Electron Microscope ◽  
Chemical Analysis ◽  
Transmission Electron Microscope ◽  
Elemental Analysis ◽  
Small Particles ◽  
X Ray ◽  
Proportionality Constant ◽  
Quantitative Elemental Analysis ◽  
Transmission Electron ◽  
Measured Characteristic

The quantitative elemental analysis of small particles can be performed in the transmission electron microscope by use of an energy dispersive X-ray detector and multichannel analyzer. As recently suggested by Cliff and Lorimer (1), Equation 1is used to determine a calibration curve of X-ray intensities relative to silicon for the accurate chemical analysis of thin particles. In this equation, I1 and I2 are the measured characteristic X-ray intensities of the two elements in question, C1 and C2 are the weight fractions and k is a proportionality constant. Absorption, atomic number and fluorescence corrections in transparent particles are assumed to be negligible at an electron accelerating voltage of 100 keV.

How accurate is ALCHEMI for ordering measurements?

2001 ◽  
Vol 7 (S2) ◽  
pp. 338-339
Author(s):  
Nan Jiang
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Theoretical Calculations ◽  
Systematic Errors ◽  
Intermetallic Alloy ◽  
X Ray ◽  
Transmission Electron ◽  
Accuracy Of Measurement ◽  
Delocalization Effects

Atom location by channeling-enhanced microanalysis (ALCHEMI) promises a straightforward measurement of ordering in materials. On tilting the electron beam in a transmission electron microscope (TEM) about a superlattice Bragg position the electron channeling changes, weighting X-ray production from each of the sublattices differently. The overall X-ray signal, converted to an apparent composition via a kinematical non-channeling standardization, moves between the composition of the constitute sublattices. However, the accuracy of measurement always bothers many researchers. Results may vary from time to time, and in the worse cases, the composition outputs are nonsense. Table 1 gives an example of a series of ALCHEMIC measurements in a B2 Ti50Al42Mo8 intermetallic alloy.In general, two major sources cause errors in ALCHEMI: weak channeling and delocalization effects. The later only results in “systematic errors”, which can always be corrected or reduced by theoretical calculations. However, it is difficult to improve the error due to weak channeling.

Transmission Electron Microscopy a Powerful Means to Investigate the Glazed Coating of Ancient Ceramics

2009 ◽  
Vol 8 ◽  
pp. 141-146 ◽  
Author(s):  
Claude Mirguet ◽  
Christian Roucau ◽  
Philippe Sciau
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Electron Microscope ◽  
High Resolution ◽  
Chemical Analysis ◽  
Energy Loss ◽  
X Ray ◽  
Transmission Electron ◽  
Powerful Means

Optical microscopy allows observation of details of the order of micrometers. In an electron microscope that uses an electron beam to make an image, the resolution is a thousand times better. It becomes possible to observe details of the nanometer (nm) in conventional mode and order of the Angstrom (1 Å = 0.1 nm) in high resolution mode. This technique requires a delicate preparation of samples to be sufficiently thin (≤ 100 nm) to allow the passage of electrons to an observation in transmission. The transfer of energy between incident electrons and atoms in the sample are operated through energy loss spectroscopy (EELS) and X-ray emission (EDX) to perform a chemical analysis of the observed object. The purpose of this paper is to show, through some examples, the potential of transmission electron microscopy and related techniques in the study of structure and composition of heritage materials.

X-ray microanalysis of thin specimens in the transmission electron microscope at voltages up to 1000 Kv.

1978 ◽  
Vol 36 (1) ◽  
pp. 540-541
Author(s):  
G. Cliff ◽  
M.J. Nasir ◽  
G.W. Lorimer ◽  
N. Ridley
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Weight Fraction ◽  
Present Series ◽  
Constant Independent ◽  
X Ray ◽  
Transmission Electron ◽  
Series Of Experiments ◽  
Image Position ◽  
X Ray Absorption

In a specimen which is transmission thin to 100 kV electrons - a sample in which X-ray absorption is so insignificant that it can be neglected and where fluorescence effects can generally be ignored (1,2) - a ratio of characteristic X-ray intensities, I1/I2 can be converted into a weight fraction ratio, C1/C2, using the equationwhere k12 is, at a given voltage, a constant independent of composition or thickness, k12 values can be determined experimentally from thin standards (3) or calculated (4,6). Both experimental and calculated k12 values have been obtained for K(11<Z>19),kα(Z>19) and some Lα radiation (3,6) at 100 kV. The object of the present series of experiments was to experimentally determine k12 values at voltages between 200 and 1000 kV and to compare these with calculated values.The experiments were carried out on an AEI-EM7 HVEM fitted with an energy dispersive X-ray detector.

Thickness and composition determinations from T.E.M. specimens using both x-ray and backscattered electron data

1984 ◽  
Vol 42 ◽  
pp. 576-577
Author(s):  
M.D. Ball ◽  
H. Lagace ◽  
M.C. Thornton
Keyword(s):  
Electron Microscope ◽  
Atomic Number ◽  
Transmission Electron Microscope ◽  
Convenient Method ◽  
Flow Chart ◽  
X Ray ◽  
Intensity Measurements ◽  
Transmission Electron ◽  
Electron Intensity ◽  
Backscattered Electron

The backscattered electron coefficient η for transmission electron microscope specimens depends on both the atomic number Z and the thickness t. Hence for specimens of known atomic number, the thickness can be determined from backscattered electron coefficient measurements. This work describes a simple and convenient method of estimating the thickness and the corrected composition of areas of uncertain atomic number by combining x-ray microanalysis and backscattered electron intensity measurements.The method is best described in terms of the flow chart shown In Figure 1. Having selected a feature of interest, x-ray microanalysis data is recorded and used to estimate the composition. At this stage thickness corrections for absorption and fluorescence are not performed.

Luminescent Properties of Gd2MoO6:Eu3+ Nanophosphor for WLEDs

2021 ◽  
Author(s):  
Yan Chen ◽  
Yuemei Lan ◽  
Dong Wang ◽  
Guoxing Zhang ◽  
Wenlong Peng ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Fluorescence Spectra ◽  
Solvothermal Method ◽  
Luminescent Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

A series of Gd2-xMoO6:xEu3+(x=0.18-0.38) nanophosphors were synthesized by the solvothermal method. The properties of this nanophosphor were characterized by x-ray diffraction (XRD), transmission electron microscope (TEM), fluorescence spectra and diffuse...

Formation of Graphite Encapsulated Nickel Nanoparticles by Ball Milling and Annealing of Expanded Graphite with Nickel

2011 ◽  
Vol 80-81 ◽  
pp. 217-220 ◽  
Author(s):  
Xue Qing Yue ◽  
Hai Jun Fu ◽  
Da Jun Li
Keyword(s):  
Electron Microscope ◽  
Ball Milling ◽  
Transmission Electron Microscope ◽  
Nickel Nanoparticles ◽  
Size Range ◽  
Expanded Graphite ◽  
X Ray Diffraction ◽  
X Ray ◽  
Nickel Powders ◽  
Transmission Electron

Graphite encapsulated nickel nanoparticles were prepared by ball milling andsubsequently annealing a mixture of expanded graphite with nickel powders. The products were characterized by transmission electron microscope and X-ray diffraction. The formation mechanism of the products was discussed. Results show that the products have a size range of 20-150 nm. The graphite and nickel in the products all exhibit a high crystallinity.

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