ORCID Profile
0009-0000-8708-0768
Current Organisation
US Army Research Laboratory
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Publisher: Wiley
Date: 30-07-2021
DOI: 10.1111/JACE.18039
Abstract: Compositional analysis of boron carbide on nanometer length scales to examine or interpret atomic mechanisms, for ex le, solid‐state amorphization or grain‐boundary segregation, is challenging. This work reviews advancements in high‐resolution microanalysis to characterize multiple generations of boron carbide. First, ζ‐factor microanalysis will be introduced as a powerful (scanning) transmission electron microscopy ((S)TEM) analytical framework to accurately characterize boron carbide. Three case studies involving the application of ζ‐factor microanalysis will then be presented: (1) accurate stoichiometry determination of B‐doped boron carbide using ζ‐factor microanalysis and electron energy loss spectroscopy, (2) normalized quantification of silicon grain‐boundary segregation in Si‐doped boron carbide, and (3) calibration of a scanning electron microscope X‐ray energy‐dispersive spectroscopy (XEDS) system to measure compositional homogeneity differences of B/Si‐doped arc‐melted boron carbides in the as‐melted and annealed conditions. Overall, the improvement and application of advanced analytical tools have helped better understand processing–microstructure–property relationships and successfully manufacture high‐performance ceramics.
Publisher: Springer Science and Business Media LLC
Date: 1997
DOI: 10.1557/PROC-480-49
Abstract: With the advent of the modem analytical electron microscope with its ultrahigh vacuum conditions, extremely high current density in a very small probe, and its light element analysis capability, it is imperative that contamination of the TEM s le, particularly by hydrocarbons, is eliminated. The degree of cleanliness required for analysis using surface sensitive techniques is also much greater than for other forms of analysis. Contamination of s les can occur (a) prior to analysis, due to the way s les are prepared or handled, or (b) during analysis. Ex les of surface contamination prior to analysis and during analysis will be given, in order to illustrate their effect on an analysis.Polished Si, Ni, and Ti bulk s les and pre-thinned TEM Ni and Ti s les were intentionally contaminated by two methods. One set of s les was put on a liquid nitrogen cooled stage for one hour in a diffusion pumped Gatan Duomill in which the liquid nitrogen cold trap above the diffusion pump was intentionally left warm. The other set was contaminated by dipping them into a 100 ml solution of acetone containing 0.04 g of an acetone-soluble low temperature wax. Two commercially available plasma cleaners, specifically designed for eliminating hydrocarbon contamination, were used to clean the s les. The bulk s les were examined with x-ray photoelectron spectroscopy and the TEM s les were examined in a 200 keV analytical TEM. The results from these experiments will be discussed.
Publisher: Wiley
Date: 09-04-2019
DOI: 10.1111/JACE.16457
Publisher: AIP Publishing
Date: 20-06-1994
DOI: 10.1063/1.111257
Abstract: The objective of this letter is to report on the successful deposition of SiC by pulsed laser deposition at room temperature. Deposition of SiC films is accomplished by ablating a 6H-SiC target, using the 248 nm radiation from a KrF* excimer laser. X-ray photoelectron spectroscopy data conclusively show that the films are silicon carbide. The Si 2p peaks are observed from a film at 100.3 eV, from a 6H-SiC standard at 100.3 eV, and from a Si standard at 99.7 eV. Similar scans of the C 1s peak reveal a shift in binding energy from 284.7 eV for a graphite standard, to 283.3 eV for a deposited film, and 283.4 eV for the SiC standard. Further, the integrated areas and shapes of the peaks from the film and the SiC standard are equivalent. Transmission electron microscopy reveals a film microstructure which is largely amorphous, but which contains a significant volume fraction of SiC crystallites. Analysis of the electron diffraction patterns indicates that the crystallites are β-SiC. The relationship between the film microstructure and the energy contained within the laser-generated plume is also considered.
No related grants have been discovered for Scott Walck.