This paper presents a new method for creating and monitoring controlled localized negatively charged regions inside insulators with a scanning electron microscope (SEM). A localized buried charged region is created and observed close to the point where a high voltage primary beam (10 kV) strikes a metal–insulator–silicon specimen. The amount of buried charge within the insulator at any given moment can be dynamically monitored by detecting the appearance of a second peak in the secondary electron (SE) energy spectrum. SE energy spectral signals were obtained through the use of a compact high signal-to-noise energy analyzer attachment that was fitted on to the SEM specimen stage. An electrostatic model, together with Monte Carlo simulations, is presented to explain how the SE charge contrast effect functions. This model is then experimentally confirmed by using the SE energy spectral signal induced by a gallium ion beam inside a dual focused ion beam-SEM instrument.

In this work, we compare the results of different Cliff–Lorimer (Cliff & Lorimer 1975) based methods in the case of a quantitative energy dispersive spectrometry investigation of light elements in ternary C–O–Si thin films. To determine the Cliff–Lorimer (C–L) k-factors, we fabricated, by focused ion beam, a standard consisting of a wedge lamella with a truncated tip, composed of two parallel SiO2 and 4H-SiC stripes. In 4H-SiC, it was not possible to obtain reliable k-factors from standard extrapolation methods owing to the strong CK-photon absorption. To overcome this problem, an extrapolation method exploiting the shape of the truncated tip of the lamella is proposed herein. The k-factors thus determined, were then used in an application of the C–L quantification procedure to a defect found at the SiO2/4H-SiC interface in the channel region of a metal-oxide field-effect-transistor device. As in this procedure, the sample thickness is required, a method to determine this quantity from the averaged and normalized scanning transmission electron microscopy intensity is also detailed. Monte Carlo simulations were used to investigate the discrepancy between experimental and theoretical k-factors and to bridge the gap between the k-factor and the Watanabe and Williams ζ-factor methods (Watanabe & Williams, 2006).

Electron and proton microprobes, along with electron backscatter diffraction (EBSD) analysis were used to study the microstructure of the contemporary Al–Cu–Li alloy AA2099-T8. In electron probe microanalysis, wavelength and energy dispersive X-ray spectrometry were used in parallel with soft X-ray emission spectroscopy (SXES) to characterize the microstructure of AA2099-T8. The electron microprobe was able to identify five unique compositions for constituent intermetallic (IM) particles containing combinations of Al, Cu, Fe, Mn, and Zn. A sixth IM type was found to be rich in Ti and B (suggesting TiB2), and a seventh IM type contained Si. EBSD patterns for the five constituent IM particles containing Al, Cu, Fe, Mn, and Zn indicated that they were isomorphous with four phases in the 2xxx series aluminium alloys including Al6(Fe, Mn), Al13(Fe, Mn)4 (two slightly different compositions), Al37Cu2Fe12 and Al7Cu2Fe. SXES revealed that Li was present in some constituent IM particles. Al SXES mapping revealed an Al-enriched (i.e., Cu, Li-depleted) zone in the grain boundary network. From the EBSD analysis, the kernel average misorientation map showed higher levels of localized misorientation in this region, suggesting greater deformation or stored energy. Proton-induced X-ray emission revealed banding of the TiB2 IM particles and Cu inter-band enrichment.

Quantification of first series transition metal Lα X-rays is hampered by absorption and in some cases transition probabilities (fluorescence yields) varying with chemical bonding. Compound mass absorption coefficients for Fe Lα were measured in the olivine solid solution series [Forsterite (Mg2SiO4) to Fayalite (Fe2SiO4)] and the mass absorption coefficients for Fe Lα absorbed by Fe were calculated. The mass absorption coefficients vary systematically between Fo83 and Fo0. Using the measured mass absorption coefficients for both standard and unknown and by correcting for a systematic discrepancy, consistent with varying partial fluorescence yields, a good agreement between calculated k-ratios and measured k-ratios is achieved. The systematic variations allow quantification of unknown k-ratios. The described method of quantification requires modification of matrix correction routines to allow standards and unknowns to have different mass absorption coefficients, and to incorporate solid solution mass absorption coefficients and partial fluorescence yield corrections derived from regression of experimental data.

Many agrowastes are being used for energy production by combustion in power plants. This process generates huge amounts of ash, which has a potential pozzolanic activity for blending with Portland cement or hydrated lime. In this paper, the ash obtained from elephant grass (Pennisetum purpureum Schum var. purple) leaves (EGLs) was studied, including the silicon content and its distribution, the presence of other compounds, and in addition, the presence of silica bodies (phytoliths). Combustion temperatures of 450 and 650°C produced an unaltered inorganic skeleton (spodogram), whereas at 850°C, there is a sintering process because of high potassium content in the ash. Phytoliths and different types of hairs were identified, and they contained high percentages of silica. Magnesium (mainly as periclase) was distributed in the most porous parts in the interior of the leaves. The silica can react with calcium hydroxide (pozzolanic reaction) forming calcium silicate hydrates (observed by field-emission scanning electron microscopy and thermogravimetric analysis). Fixed lime percentages at 28 curing days (63%) indicated the high reactivity of EGL ashes in calcium hydroxide pastes due to the pozzolanic reaction. This study demonstrates the possibility of the reuse of ashes from EGLs for the production of environmental-friendly cements.

The accuracy to which Cu and Al coatings can be determined, and the effect this has on the quantification of the substrate, is investigated. Cu and Al coatings of nominally 5, 10, 15, and 20 nm were sputter coated onto polished Bi using two configurations of coater: One with the film thickness monitor (FTM) sensor colocated with the samples, and one where the sensor is located to one side. The FTM thicknesses are compared against those calculated from measured Cu Lα and Al Kα k-ratios using PENEPMA, GMRFilm, and DTSA-II. Selected samples were also cross-sectioned using focused ion beam. Both systems produced repeatable coatings, the thickest coating being approximately four times the thinnest coating. The side-located FTM sensor indicated thicknesses less than half those of the software modeled results, propagating on to 70% errors in substrate quantification at 5 kV. The colocated FTM sensor produced errors in film thickness and substrate quantification of 10–20%. Over the range of film thicknesses and accelerating voltages modeled both the substrate and coating k-ratios can be approximated by linear trends as functions of film thickness. The Al films were found to have a reduced density of ~2 g/cm2.

The twinning and slip modes of a rolled magnesium alloy sheet were investigated through quasi-in-situ tensile tests that were carried out along the rolling direction at room temperature with a constant strain rate. Scanning electron microscopy and electron backscattered diffraction observations were used to identify activated twinning and slip systems. Schmid factors were calculated to analyze different deformation modes. The analyses show that a small number of {10-12} tensile twins were present during deformation, and these twins resulted from the accommodation of compression along the tensile direction. Post-deformation examination revealed the dominance of prismatic <a> slip.

The ability to characterize recombination and carrier trapping processes in group-III nitride-based nanowires is vital to further improvements in their overall efficiencies. While advances in scanning transmission electron microscope (STEM)-based cathodoluminescence (CL) have offered some insight into nanowire behavior, inconsistencies in nanowire emission along with CL detector limitations have resulted in the incomplete understanding in nanowire emission processes. Here, two nanowire heterostructures were explored with STEM-CL: a polarization-graded AlGaN nanowire light-emitting diode (LED) with a GaN quantum disk and a polarization-graded AlGaN nanowire with three different InGaN quantum disks. Most nanowires explored in this study did not emit. For the wires that did emit in both structures, they exhibited asymmetrical emission consistent with the polarization-induced electric fields in the barrier regions of the nano-LEDs. In the AlGaN/InGaN sample, two of the quantum disks exhibited no emission potentially due to the three-dimensional landscape of the sample or due to limitations in the CL detection.

The spatial resolution of aberration-corrected annular dark field scanning transmission electron microscopy was studied as function of the vertical position z within a sample. The samples consisted of gold nanoparticles (AuNPs) positioned in different horizontal layers within aluminum matrices of 0.6 and 1.0 µm thickness. The highest resolution was achieved in the top layer, whereas the resolution was reduced by beam broadening for AuNPs deeper in the sample. To examine the influence of the beam broadening, the intensity profiles of line scans over nanoparticles at a certain vertical location were analyzed. The experimental data were compared with Monte Carlo simulations that accurately matched the data. The spatial resolution was also calculated using three different theoretical models of the beam blurring as function of the vertical position within the sample. One model considered beam blurring to occur as a single scattering event but was found to be inaccurate for larger depths of the AuNPs in the sample. Two models were adapted and evaluated that include estimates for multiple scattering, and these described the data with sufficient accuracy to be able to predict the resolution. The beam broadening depended on z1.5 in all three models.

Secondary fluorescence (SF), typically a minor error in routine electron probe microanalysis (EPMA), may not be negligible when performing high precision trace element analyses in multiphase samples. Other factors, notably wavelength dispersive spectrometer defocusing, may introduce analytical artifacts. To explore these issues, we measured EPMA transects across two material couples chosen for their high fluorescence yield. We measured transects away from the fluorescent phase, and at various orientations with respect to the spectrometer focal line. Compared to calculations using both the Monte Carlo simulation code PENEPMA and the semi-analytical model FANAL, both codes estimate the magnitude of SF, but accurate correction requires knowledge of the position of the spectrometer with respect to the couple interface. Positioned over the fluorescent phase or otherwise results in a factor of 1.2–1.8 of apparent change in SF yield. SF and spectrometer defocusing may introduce systematic errors into trace element analyses, both may be adequately accounted for by modeling. Of the two, however, SF is the dominant error, resulting in 0.1 wt% Zn apparently present in Al at 100 μm away from the Zn boundary in an Al/Zn couple. Of this, around 200 ppm Zn can be attributed to spectrometer defocusing.

Understanding oxide–metal interfaces is crucial to the advancement of materials and components for many industries, most notably for semiconductor devices and power generation. Atom probe tomography provides three-dimensional, atomic scale information about chemical composition, making it an excellent technique for interface analysis. However, difficulties arise when analyzing interfacial regions due to trajectory aberrations, such as local magnification, and reconstruction artifacts. Correlative microscopy and field simulation techniques have revealed that nonuniform evolution of the tip geometry, caused by heterogeneous field evaporation, is partly responsible for these artifacts. Here we attempt to understand these trajectory artifacts through a study of the local evaporation field conditions. With a better understanding of the local evaporation field, it may be possible to account for some of the local magnification effects during the reconstruction process, eliminating these artifacts before data analysis.

In this paper, three-dimensional (3D) image data of ore particle systems is investigated. By combining X-ray microtomography with scanning electron microscope (SEM)-based image analysis, additional information about the mineralogical composition from certain planar sections can be gained. For the analysis of tomographic images of particle systems the extraction of single particles is essential. This is performed with a marker-based watershed algorithm and a post-processing step utilizing a neural network to reduce oversegmentation. The results are validated by comparing the 3D particle-wise segmentation empirically with 2D SEM images, which have been obtained with a different imaging process and segmentation algorithm. Finally, a stereological application is shown, in which planar SEM images are embedded into the tomographic 3D image. This allows the estimation of local X-ray attenuation coefficients, which are material-specific quantities, in the entire tomographic image.

One of the critical prerequisites for accurately measuring the mechanical properties of profiled fibers is the precise determination of their cross-sectional areas (CSAs). In this study, a new method is established for determining a single profiled fibers’ CSA based on the frozen section method and digital photo, pixel-ratio method (FS-DP). FS-DP is used to obtain a transverse section of a fiber, by acquiring an image of the cross section using optical microscopy or scanning electron microscopy, and then calculating the CSA using Photoshop. Using FS-DP, it was found that the shape of a fiber of silk changes little in a range of 50 μm, but varies considerably over a range of 1 m, while the CSA of cocoon silk (900 m) first increases and then decreases. Mechanical property tests showed that the elongation, strength, elastic modulus, and toughness values of the cocoon silk are consistent with those reported previously. Additionally, FS-DP was also used to observe other profiled fibers. The application tests indicated that FS-DP can be used to quickly and accurately obtain the CSA of a single profiled fiber, and that it is suitable for the large-scale determination and analysis of the mechanical properties of profiled fibers.

Transmission electron microscopy (TEM) with low-energy electrons has been recognized as an important addition to the family of electron microscopies as it may avoid knock-on damage and increase the contrast of weakly scattering objects. Scanning electron microscopes (SEMs) are well suited for low-energy electron microscopy with maximum electron energies of 30 keV, but they are mainly used for topography imaging of bulk samples. Implementation of a scanning transmission electron microscopy (STEM) detector and a charge-coupled-device camera for the acquisition of on-axis transmission electron diffraction (TED) patterns, in combination with recent resolution improvements, make SEMs highly interesting for structure analysis of some electron-transparent specimens which are traditionally investigated by TEM. A new aspect is correlative SEM, STEM, and TED imaging from the same specimen region in a SEM which leads to a wealth of information. Simultaneous image acquisition gives information on surface topography, inner structure including crystal defects and qualitative material contrast. Lattice-fringe resolution is obtained in bright-field STEM imaging. The benefits of correlative SEM/STEM/TED imaging in a SEM are exemplified by structure analyses from representative sample classes such as nanoparticulates and bulk materials.

When analyzing an unknown by electron-excited energy dispersive X-ray spectrometry, with the entire periodic table possibly in play, how does the analyst discover minor and trace constituents when their peaks are overwhelmed by the intensity of an interfering peak(s) from a major constituent? In this paper, we advocate for and demonstrate an iterative analytical approach, alternating qualitative analysis (peak identification) and standards-based quantitative analysis with peak fitting. This method employs two “tools”: (1) monitoring of the “raw analytical total,” which is the sum of all measured constituents as well as any such as oxygen calculated by the method of assumed stoichiometry, and (2) careful inspection of the “peak fitting residual spectrum” that is constructed as part of the quantitative analysis procedure in the software engine DTSA-II (a pseudo-acronym) from the National Institute of Standards and Technology. Elements newly recognized after each round are incorporated into the next round of quantitative analysis until the limits of detection are reached, as defined by the total spectrum counts.