Scanning Electron Microscope Imaging Technique Research Articles

Quantitative analysis of the correlation between sp3 bonds and functional groups in covalently functionalized single-walled carbon nanotubes

The potential of carbon nanotube (CNT)-based applications in diverse scientific fields has been demonstrated by achieving precise control of their surfaces through chemical functionalization. However, the formation of fatal defects like sidewall cleavage is an increasingly important concern as it significantly degrades the performance of CNTs. The presence of these structural disruptions has been ascertained by transmission electron microscopy, but a comprehensive understanding of their surface remains unclear due to its highly localized observation. Here, we demonstrate a framework for quantitative evaluation of the relationship between sp3 bonds and functional groups on CNT surface by combining μ-Raman and energy dispersive X-ray spectroscopy in scanning electron microscope imaging techniques. Nonuniform features of the degree of functionalization in strongly oxidized two types of single-walled CNTs are appropriately visualized in both measurements, allowing a systematic assessment of the surface states. Quantitative analysis reveals that the nm-scale sidewall openness during the chemical process is adequately explained by introducing a variable θ defined as the ratio of the degree of functionalization/defect density. These findings can be widely utilized as a novel evaluation technique to control the reactivity in the surface functionalization of various carbon nanomaterials.

Feasibility study of using waste badminton string fibers in con-crete by morphological, microstructural and tensile characteristics

As the strings are cut off from the badminton racquet system, the whole string will be replaced with a new one and there is no other alternative. Hence those cut-off strings are considered as waste and cannot be recycled, tons of waste are retained as debris. Among many research on recycled synthetic fiber, this application of waste material is a new context in sustainable construction. Here five different samples are examined based on wide usage, recycled Waste Badminton String Fiber (WBSF) is characterized and physically examined using a Scanning Electron Microscope, Fourier Transform Infrared Spectroscopy, and X-ray diffraction to use it as a recycled synthetic fiber in various fiber reinforced concrete applications. The diameter and cross-sectional area of WBSF are studied using the Scanning Electron Microscope imaging technique and Image J application, which shows that the fiber is highly engineered with 3 layers namely elasticity outer, outer layer, and core fiber with the mean diameter and net cross-sectional area is 777.6 µm and 5,05,959 µm2 respectively. The surface roughness of fiber is analyzed using ImageJ application which varies between 16-32 nm. The fiber samples are subjected to tensile loading the average tensile stress lies between 544.34 - 639.94 MPa. From the above examinations, the accurate diameter, net cross-sectional area, and voided area of the WBSF are calculated. The structural property and polymer relationship of the fiber are investigated using the X-ray diffraction technique and Fourier transform infrared spectroscopy, this reveals that the WBSF is of polyamide 6,6 form. The superior tensile stress compared to other recycled nylon fibers. So, the use of waste badminton string fiber in concrete is a new merging idea for fiber-reinforced concrete applications like pavements, pipes, tunnel lining, and other structural elements.

An advantageous imaging perspective for quantitative evaluation of 7075 aluminum alloy grain boundary precipitates using scanning electron microscope.

7075 Aluminum alloy (AA7075) samples undergone four aging sequences were examined using a scanning electron microscope (SEM) and a transmitted electron microscope (TEM). The measurements results validate the correlation between stress corrosion cracking (SCC) resistance and the size and inter-distance of the grain boundary precipitates (GBPs). To evaluate the size and inter-distance of GBPs, we demonstrate in this study a highly efficient SEM imaging technique that can unfold grain boundary in a two-dimensional view. Compared to TEM, imaging with backscattered electrons in SEM (SEM-BSE) is more advantageous for GBPs presentation and measurements. The major reason is that about 900 times more sampling area can be imaged with SEM from the same specimen for TEM observation, thus enabling frequent appearances of GBPs at normal top view perspective, a planar view best for GBPs quantitative analysis but not well-documented. The acceleration tension of SEM for imaging was optimized at 10kV with an information depth of around 330 nm. RESEARCH HIGHLIGHTS: Scanning electron microscope (SEM) imaging using backscattered electrons is efficient for AA7075 grain boundary precipitate imaging. The precipitate size and inter-distance can be more accurately measured with the perspective of normal top view under SEM than transmitted electron microscope.

Structural and chemical resetting processes in white mica and their effect on K-Ar data during low temperature metamorphism

White mica has been widely used to date microstructures and tectonic events in faults, shear-zones and folds because of its suitability for radiogenic dating. However, complex (i) microstructural evolution, (ii) individual chemical evolution of the K-bearing phases, (iii) mixing of ‘detrital grains’ with newly formed and/or recrystallized or chemically reset grains as well as (iv) volume diffusion may result in apparent K-Ar ages. Here, specimens from a prograde sediment sequence of the exhumed fossil European Alpine accretionary wedge were used to investigate resetting processes of white mica by the type and intensity of deformation as well as peak metamorphic conditions. We combine the K-Ar system with mass and mineral quantities from grain size fractions to calculate the amount of recrystallized white mica in each grain size fraction along the metamorphic gradient. Increasing recrystallization with increasing metamorphic grade is related to thermally activated pressure solution and dissolution-precipitation creep, as seen by the formation of a spaced cleavage of recrystallized phyllosilicates documented through Synchrotron X-ray Fluorescence Microscopy and Scanning Electron Microscope imaging techniques. Increasing recrystallization by dissolution-precipitation processes induces chemical resetting of the isotopic system, resulting in a prograde decrease of apparent K-Ar ages. We demonstrate that Ar volume diffusion does not play a significant role for the low-temperature samples, promoting recrystallization as the important physico-chemical process for age resetting. However, white mica chemistry reveals that no simple relation between isotopic resetting and grain size exists along the prograde path. Reliable age information can therefore only be obtained in the case of (nearly) complete resetting, which accounts only for the smallest grain size fraction at the highest metamorphic temperature. These findings could shed new light on accurate dating of mica-rich fault rocks, where the time constraints depend not only on the temperature, but also on the amount and type of deformation.

Determination of Hamaker constant for CNT and AFM probe configuration inside SEM

Mounting the atomic force microscope (AFM) probe on the gripper of the robotic nanoscale manipulators system enables the combination of the AFM and scanning electron microscope (SEM). The AFM–SEM-based method of determining Hamaker constant for carbon nanotube (CNT) and AFM cantilever in the vacuum condition of SEM, which is completed through a robotic nanoscale manipulators system, is presented for the first time. During Hamaker constant determining experiment, the elastic force is measured utilising integrated AFM–SEM imaging technique through detecting the deflection of AFM cantilever that actually equals van der Waals adhesion force. The van der Waals attraction force between CNT and AFM cantilever is calculated through the modelling of a cylindrical nanotube and a flat gold-coated surface. The experiment results indicate that Hamaker's constant measured are comparable to typical values published by previous researchers, being of the order of 100 zJ, which indicates that the present approach is valid and reliable.

Targeted Studies Using Serial Block Face and Focused Ion Beam Scan Electron Microscopy.

This protocol allows for the efficient and effective imaging of cell or tissue samples in three dimensions at the resolution level of electron microscopy. For many years electron microscopy (EM) has remained an inherently two-dimensional technique. With the advent of serial scanning electron microscope imaging techniques (volume EM), using either an integrated microtome or focused ion beam to slice then view embedded tissues, the third dimension becomes easily accessible. Serial block face scanning electron microscopy (SBF-SEM) uses an ultramicrotome enclosed in the SEM chamber. It has the capability to handle large specimens (1,000 µm x 1,000 µm) and image large fields of view at small X,Y pixel size, but is limited in the Z dimension by the diamond knife. Focused ion beam SEM (FIB-SEM) is not limited in 3D resolution, (isotropic voxels of ≤5 nm are achievable), but the field of view is much more limited. This protocol demonstrates a workflow for combining the two techniques to allow for finding individual regions of interest (ROIs) in a large field and then imaging the subsequent targeted volume at high isotropic voxel resolution. Preparing fixed cells or tissues is more demanding for volume EM techniques due to the extra contrasting needed for efficient signal generation in SEM imaging. Such protocols are time consuming and labor intensive. This protocol also incorporates microwave assisted tissue processing facilitating the penetration of reagents, which reduces the time needed for the processing protocol from days to hours.

Pore-structure, hydrophilicity, and particle filtration characteristics of polyaniline–polysulfone ultrafiltration membranes

A highly processable form of polyaniline was synthesized and used to form pure polyaniline and polyaniline–polysulfone ultrafiltration membranes by nonsolvent induced phase inversion. Blends containing up to 75% polyaniline were 10–20% more permeable than pure polysulfone membranes, while pure polyaniline membranes were 10 times more permeable and extremely hydrophilic. A novel scanning electron microscope imaging technique was combined with characterization data and the Hagen–Poiseuille pore-flow model to elucidate that increasing polyaniline content increased the apparent membrane pore size and hydrophilicity, while decreasing skin layer thickness and porosity. Pure polyaniline membranes exhibited relatively larger, shorter pores that combined with the increased hydrophilicity to produce the observed separation performance enhancements.

A method of visualization of dispersion of nanoplatelets in nanocomposites

Air plasma etching followed by scanning electron microscope imaging technique for visualizing the inorganic nanofillers in polymeric composites is a promising technique for quick screening of exfoliation and dispersion of nanofillers in nanocomposites in manufacturing and materials development environments. The method was applied to study montmorillonite (MMT) clay with vinyl ester nanocomposite samples produced using high shear mixing. Results were compared with transmission electron microscope data. The study details the versatility and the use of this technique for visualization of inorganic platelets. The etch rate for MMT/vinyl ester and neat resin initially was 3 and 4 nm/min and increased to about 8 and 10 nm/min, respectively.

High-temperature electron backscatter diffraction and scanning electron microscopy imaging techniques: in-situ investigations of dynamic processes.

In-situ heating experiments have been conducted at temperatures of approximately 1200 K utilising a new design of scanning electron microscope, the CamScan X500. The X500 has been designed to optimise the potential for electron backscatter diffraction (EBSD) analysis with concomitant in-situ heating experimentation. Features of the new design include an inclined field emission gun (FEG) column, which affords the EBSD geometrical requirement of a high (typically 160 degrees) angle between the incoming electron beam and specimen surface, but avoids complications in heating-stage design and operation by maintaining it in a horizontal orientation. Our studies have found that secondary electron and orientation contrast imaging has been possible for a variety of specimen materials up to a temperature of at least 900 degrees C, without significant degradation of imaging quality. Electron backscatter diffraction patterns have been acquired at temperatures of at least 900 degrees C and are of sufficient quality to allow automated data collection. Automated EBSD maps have been produced at temperatures between 200 degrees C and 700 degrees C in aluminium, brass, nickel, steel, quartz, and calcite, and even at temperatures >890 degrees C in pure titanium. The combination of scanning electron microscope imaging techniques and EBSD analysis with high-temperature in-situ experiments is a powerful tool for the observation of dynamic crystallographic and microstructural processes in metals, semiconductor materials, and ceramics.