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The subsurface damage in the laser machining process dramatically affects the mechanical properties and the service life of the cemented tungsten carbide. To further reveal the interaction mechanics, the subsurface damage characteristics of WC/8Co cemented carbide ablated by a nanosecond UV laser is explored through the angle polishing method, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) combined with focused ion beam (FIB) milling. The results show that severe cracking and crushing behaviors appear in the re-solidified areas and the heat-affected zone (HAZ). Based on the temperature field and stress field simulation results, the high temperature gradient induced thermal stress is responsible for the subsurface damage behavior. The blocking of the ablated groove caused by the solidification of the melted material is identified. The XPS spectrums indicate that the machined cemented tungsten carbide is seriously oxidized in the surface and to some extent in the subsurface layer, with the main oxidization products to be WO3, CoWO4, WO2, CoO and Co3O4. In addition, the deformation behavior of WC grain and the disordered alignment of Co atoms are identified in the re-solidified area and HAZ.

In unconventional reservoirs, the pore space is hosted by a heterogeneous matrix with various minerals and organic components. This heterogeneity complicates petrophysical interpretation during hydrocarbon exploration. A digital rock physics study of thermal and electrical conductivity was conducted using high-resolution focused ion beam scanning electron microscopy images of carbonate-rich source rocks. Finite-volume simulation results are discussed in context of the sample heterogeneity and anisotropy and supported by comparisons to empirical equations and effective medium theory. The results show how the presence of organic matter, pyrite, and pore constrictions impacts application of empirical equations and simplified models to unconventional reservoirs.Graphic abstract

Electronic regulation of two-dimensional (2D) transition metal dichalcogenides (TMDCs) is a crucial step towards next-generation optoelectronics and electronics. Here, we demonstrate controllable and selective-area defect engineering in 2D molybdenum disulfide (MoS2) using a focused ion beam with a low-energy gallium ion (Ga+) source. We find that the surface defects of MoS2 can be tuned by the precise control of ion energy and dose. Furthermore, the field-effect transistors based on the monolayer MoS2 show a significant threshold voltage modulation over 70 V after Ga+ irradiation. First-principles calculations reveal that the Ga impurities in the monolayer MoS2 introduce a defect state near the Fermi level, leading to a shallow acceptor level of 0.25 eV above the valence band maximum. This defect engineering strategy enables direct writing of complex pattern at the atomic length scale in a controlled and facile manner, tailoring the electronic properties of 2D TMDCs for novel devices.

To realize quantum tunneling applications with movable electrodes, sharp tips with radii down to several tens of nanometers are necessary. The use of a focused ion beam (FIB) and focused electron beam (FEB) with a gas injection system (GIS) allows the integration of geometries in the nanoscale directly into micro and nano systems. However, the implementation of the tunneling effect clearly depends on the material. In this work, a metal-organic precursor is used. The investigation of the prepared tunneling electrodes enables an insight into FIB/FEB parameters for the realization of quantum tunneling applications. For this purpose, a high-resolution transmission electron microscopy (HRTEM) analysis is performed. The results show a dependence of the material nanostructure regarding platinum (Pt) grain size and distribution in an amorphous carbon matrix from the used beam and the FIB currents. The integration of the tips into a polysilicon (PolySi) beam and measuring the current signal by approaching the tips show significant differences in the results. Moreover, the approach of FEB tips shows a non-contact behavior even when the tips are squeezed together. The contact behavior depends on the grain size, proportion of platinum, and the amount of amorphous carbon in the microstructure, especially at the edge area of the tips. This study shows significant differences in the nanostructure between FIB and FEB tips, particularly for the FIB tips: The higher the ion current, the greater the platinum content, the finer the grain size, and the higher the probability of a tunneling current by approaching the tips.

Multilayered thermoelectric material bismuth telluride (Bi2Te3) is widely used in engineering owing to its exceptional thermoelectric performance at room temperature. However, Bi2Te3 is prone to cracks, voids, or other defects due to its multilayered structure, leading to decreased device lifetime and reliability. This paper aims at stably and precisely measuring the interlaminar fracture toughness (IFT) of multilayered Bi2Te3 for the reliability evaluation of Bi2Te3-based thermoelectric devices. In addition, we seek a method to stably measure the IFT even for very brittle materials. We developed a tapered cantilever bending (TCB) experiment to obtain the IFT. The experimental specimens were fabricated using a focused ion beam (FIB) technique at the micro scale, and the initial interlaminar crack was introduced by the notch method. By performing the TCB experiment, we created an ideally sharp pre-crack and observed stable crack propagation. The critical energy release rate (ERR) for crack propagation obtained in the present paper is around 0.51–0.53 J/m2, which agrees reasonably with theoretical van der Waals (vdW) interlaminar interaction energy. The proposed method can be well-applied in assessing IFTs of multilayered materials, even for very brittle multilayered 2D materials.

Understanding compositional and microstructural changes in functional intermetallic coatings is of great importance for fusion energy and nuclear materials applications. Tritium (3H) and lithium (6Li, 7Li) transport within a neutron irradiated target rod employing an aluminide-coated austenitic stainless-steel cladding was investigated using state-of-the-art multimodal imaging. Specifically, a scanning electron microscope augmented with focused ion beam (SEM-FIB) was used to prepare lift-out samples of the irradiated coating for microanalysis. Scanning transmission electron microscopy (STEM) was used to acquire atomic-scale information on the coating surface microstructure, morphology, and composition. Atomic force microscopy (AFM) was used to determine lift-out dimensions nondestructively. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) revealed the presence of carbonaceous species and unexpected lithium isotopic distributions in the irradiated tubing, suggesting light isotope mobility between internal target components during irradiation. SIMS chemical mapping of aluminide coatings at core midplane and lower core locations of the cladding shows that light isotopic (e.g., 3H, 6Li, 7Li) distributions are different in the irradiated coating. Advance correlative imaging results suggest lithium transport during the tritium production process and give new insights into the fundamental transport mechanism within the target during irradiation and non-equilibrium conditions.

In recent years there has been an increasing effort in improving the performance of Nb3Sn for high-field applications, in particular for the fabrication of conductors suitable for the realization of the Future Circular Collider (FCC) at CERN. This challenging task has led to the investigation of new routes to advance the high-field pinning properties, the irreversibility and the upper critical fields (HIrr and Hc2, respectively). The effect of hafnium addition to the standard Nb-4Ta alloy has been recently demonstrated to be particularly promising and, in this paper, we investigate the origins of the observed improvements of the superconducting properties. Electron microscopy, Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS) and Atom Probe Tomography (APT) characterization clearly show that, in presence of oxygen, both fine Nb3Sn grains and HfO2 nanoparticles form. Although EXAFS is unable to detect significant amounts of Hf in the A15 structure, APT does indeed reveal some residual intragrain metallic Hf. To investigate the layer properties in more detail, we created a microbridge from a thin lamella extracted by Focused Ion Beam (FIB) and measured the transport properties of Ta-Hf-doped Nb3Sn. Hc2(0) is enhanced to 30.8 T by the introduction of Hf, ~ 1 T higher than those of only Ta-doped Nb3Sn, and, even more importantly the position of the pinning force maximum exceeds 6 T, against the typical ~ 4.5–4.7 T of the only Ta-doped material. These results show that the improvements generated by Hf addition can significantly enhance the high-field performance, bringing Nb3Sn closer to the requirements necessary for FCC realization.

High-temperature superconductor (HTS) Josephson junctions (JJs) are primarily based on artificial grain boundaries. Bi-crystal JJs are typically utilized in HTS superconducting quantum interference devices (SQUIDs). However, the performances of bi-crystal JJs depend significantly on the quality of the interface at the junction. In this study, we investigate a method for forming nanobridge JJs via gallium focused ion beam (FIB) irradiation. A 100-nm-thick YBa2Cu3O7- δ was deposited on an MgO (100) substrate via pulsed laser deposition. An additional 20-nm-thick Au layer, which serves as a protection layer preventing ion damage during alignment, was deposited in situ. HTS microchannels with a width of 4 μm were defined via photolithography and argon ion milling. The HTS microchannel widths are decreased via FIB line scans to create nanobridges. The JJs are fabricated using two types of HTS thin films, in which one has a higher critical current density ( J C) that the other. The fabrication process using the gallium FIB was optimized and nanobridges with a junction width of 80 nm were prepared. As a result, a better with higher J C (5 MA/cm2) HTS films allowed for making junctions exhibiting up to five Shapiro steps at 77 K.

The 3D Focused Ion Beam - Scanning Electron Microscopy (FIB-SEM) technique has been used to study the ceramic microstructures with the accuracy of tens of nanometers. There are several reports about the 3D reconstruction about the Ni-YSZ electrode in SOFC or SOEC mode (1-3). In this work, samples taken from full size, 10×10 cm2, solid oxide fuel cell (SOFC) single cells were reconstructed with the FIB-SEM tomography. Three samples were chosen from the same production batch, including a cell without reduction, a cell with 5 hours reduction and a cell with 100 hours test with humidified hydrogen, respectively. Figure 1 shows the SEM micrograph and reconstructed anode for the cell after 100 hours test. Different from the button cells, the full size anode-supported SOFC need a strong support layer and a smaller porosity is also acceptable. The lattice Boltzmann method (LBM) was used to simulate the physical processed in the reconstructed porous electrode. The 3D microstructure was remeshed to cubic voxels for numerical analysis. The triple-phase-boundary length was automatically identified and the parameters in the exchange current density equation were fitted to the polarization curves. Detailed results will be submitted in the full length draft. References 1. Z. Jiao, N. Shikazono, and N. Kasagi, J. Electrochem. Soc., 159 (3), B285 (2012). 2. M. Trini, P.S. Jørgensen, A. Hauch, J.J. Bentzen, P.V. Hendriksen, M. Chen, 3D microstructural characterization of Ni/YSZ electrodes exposed to 1 Year of electrolysis testing, J. Electrochem. Soc., 166 (2), F1 (2019). 3. M. Trini, A. Hauch, S. De Angelis, X. Tong, P. Vang Hendriksen, and M. Chen, J. Power Sorces, 450, 227599 (2020). 4. D. Kanno, N. Shikazono, N. Takagi, K. Matsuzaki, and N. Kasagi, Electrochimi. Acta, 56, 4015, 2011. Figure 1

In the literature and industrial experience, the effect of insufficient and poor manganese phosphate coating formation on steel with higher chromium content (> 1 wt%) is well known, but the reason for this limitation or the appearance and tribological performance of such coatings is not described sufficiently. This work describes the differences in structure and tribological properties of manganese phosphate coatings on different steels with up to 3 wt% of chromium and reveals the formation of amorphous and crystalline phosphate phases by transmission electron microscopy (TEM). The tribological experiments were performed on a high load test setup with API modified as lubricant. Besides TEM also scanning electron microscopy, and focused ion beam cross sections were employed to investigate the microstructure and appearance of the coatings. Furthermore, this work describes the formation of tribologically superior coatings on martensitic steel with up to 3 wt% chromium.

Phase-separated polymer films are commonly used as coatings around pharmaceutical oral dosage forms (tablets or pellets) to facilitate controlled drug release. A typical choice is to use ethyl cellulose and hydroxypropyl cellulose (EC/HPC) polymer blends. When an EC/HPC film is in contact with water, the leaching out of the water-soluble HPC phase produces an EC film with a porous network through which the drug is transported. The drug release can be tailored by controlling the structure of this porous network. Imaging and characterization of such EC porous films facilitates understanding of how to control and tailor film formation and ultimately drug release. Combined focused ion beam and scanning electron microscope (FIB-SEM) tomography is a well-established technique for high-resolution imaging, and suitable for this application. However, for segmenting image data, in this case to correctly identify the porous network, FIB-SEM is a challenging technique to work with. In this work, we implement convolutional neural networks for segmentation of FIB-SEM image data. The data are acquired from three EC porous films where the HPC phases have been leached out. The three data sets have varying porosities in a range of interest for controlled drug release applications. We demonstrate very good agreement with manual segmentations. In particular, we demonstrate an improvement in comparison to previous work on the same data sets that utilized a random forest classifier trained on Gaussian scale-space features. Finally, we facilitate further development of FIB-SEM segmentation methods by making the data and software used open access.Drug release from pharmaceutical tablets or pellets is often controlled by applying a phase-separated polymer film coating. Ethyl cellulose and hydroxypropyl cellulose (EC/HPC) polymer blends are commonly used. The HPC phase leaches out when in contact with water and the result is a porous EC matrix coating, with mass transport properties that can be controlled by tailoring the structure of the porous network. High-resolution 3D imaging is necessary to characterize such materials, and the resolution of e.g. X-ray computed tomography is simply insufficient. Combined focused ion beam and scanning electron microscope (FIB-SEM) tomography on the other hand is a suitable technique, but segmentation of FIB-SEM data, in this case to separate the solid matrix and the porous network, is challenging. In this work, we develop a method for segmentation of FIB-SEM image data acquired from three different EC porous films where the HPC phases have been leached out. The segmentation is based on convolutional neural networks (CNNs). CNNs is a well-established machine learning paradigm and has demonstrated state-of-the-art performance in many image analysis and segmentation tasks. CNNs are inspired from biological processes in the visual cortex and act similarly, at least conceptually. In contrast to most conventional machine learning algorithms, CNNs learn by themselves which features to extract from the images. The features are extracted at different spatial scales and may constitute e.g. edge and contrast detectors. These features are subsequently used for classification. In this work, CNNs are used for image segmentation. The goal is to identify which regions in the images that contain either pore (empty space) or solid (material), hence a binary classification task. For the CNN to learn how to perform such a task, a ground truth is needed. This is achieved by letting an expert manually segment parts of the data. This is a very time-consuming endeavor, hence only a small random subset of the full dataset is manually segmented. The CNN is trained for the task using the manually segmented data, after which automatic segmentation of the full dataset is performed. We obtain very good agreement with manual segmentations in terms of accuracy and porosity, and a clear improvement in comparison to an earlier developed random forest classifier trained on Gaussian scale-space features on the same data. The development of accurate segmentation methods is a crucial step toward better understanding and tailoring of coatings for controlled drug release.

We have studied the domain forward growth (growth in polar direction) on the non-polar cut of lithium niobate crystal as a result of focused ion beam irradiation. The nonlinear dose dependencies of...

In this study, incorporation pathway(s) and distribution of reduced technetium-99 (Tc), as Tc(IV), into iron oxide/hydroxide minerals formed via oxidation and mineral transformation of the reductan...

The experiments aimed to verify the use of a focused ion beam (FIB) to create structures analogous to the natural surface and then use the two-step imprinting method to prepare replicas of the surface creat-ed by FIB. The surface of the petal leaves of pansy (Viola x wittrockiana) was selected as a natural sur-face pattern. The TESCAN AMBER FIB-SEM microscope was used for the preparation of an analo-gous surface. The molds for the replication process were made of President Light Body elastomer. PVB, PVA, CMC, PCL, EP were used for the preparation of polymer replicas. Scanning electron micro-scope was used to evaluate the quality of the prepared polymer replicas. The dimensions of the replicat-ed convex and concave structures were 25 x 20 µm. The polymers showed a different ability to copy the structure in detail. For PVA, CMC, and PCL, surface structuring at the nanometer level was described in this study. Due to the dimensions of the cones of convex and concave structures, the color was ob-served on all samples.

Focused ion beam (FIB) techniques are commonly used to machine, analyse and image materials at the micro- and nanoscale. However, FIB modifies the integrity of the sample by creating defects that cause lattice distortions. Methods have been developed to reduce FIB-induced strain, however these protocols need to be evaluated for their effectiveness. Here we use non-destructive Bragg coherent X-ray diffraction imaging to study the in situ annealing of FIB-milled gold microcrystals. We simultaneously measure two non-collinear reflections for two different crystals during a single annealing cycle, demonstrating the ability to reliably track the location of multiple Bragg peaks during thermal annealing. The thermal lattice expansion of each crystal is used to calculate the local temperature. This is compared to thermocouple readings, which are shown to be substantially affected by thermal resistance. To evaluate the annealing process, we analyse each reflection by considering facet area evolution, cross-correlation maps of displacement field and binarised morphology, and average strain plots. The crystal's strain and morphology evolve with increasing temperature, which is likely to be caused by the diffusion of gallium in gold below ~280{\deg}C and the self-diffusion of gold above ~280{\deg}C. The majority of FIB-induced strains are removed by 380-410\degree C, depending on which reflection is being considered. Our observations highlight the importance of measuring multiple reflections to unambiguously interpret material behaviour., Comment: 51 pages, 16 figures

The interest in using high vacuum-compatible time-of-flight secondary ion mass spectrometry (TOF-SIMS) detectors integrated within focused ion beam instruments (FIB) has increased due to the possib...

Helium implantation in surfaces is of interest for plasma-facing materials and other nuclear applications. Vanadium as both a representative bcc material and a material relevant for fusion applications is implanted using a Helium ion beam microscope, and the resulting swelling and nanomechanical properties are quantified. These values are put in correlation to data obtained from micro-residual stress measurements using a focused ion beam-based ring-core technique. We found that the swelling measured is similar to literature values. Further, we are able to measure the surface stress caused by the implantation and find that it approaches the yield strength of the material at blistering doses. The simple calculations performed in the present work, along with several geometrical considerations deduced from experimental results confirm the driving force for blister formation comes from bulging resulting mainly from gas pressure buildup, rather than solely stress-induced buckling. Graphic abstract: [Figure not available: see fulltext.]

Gas storage and recovery processes in shales critically depend on nano-scale porosity and chemical composition, but information about the nanoscale pore geometry and connectivity of kerogen, insoluble organic shale matter, is largely unavailable. Using adsorption microcalorimetry, we show that once strong adsorption sites within nanoscale network are taken, gas adsorption even at very low pressure is governed by pore width rather than chemical composition. A combination of focused ion beam with scanning electron microscopy and transmission electron microscopy reveal the nanoscale structure of kerogen includes not only the ubiquitous amorphous phase but also highly graphitized sheets, fiber- and onion-like structures creating nanoscale voids accessible for gas sorption. Nanoscale structures bridge the current gap between molecular size and macropore scale in existing models for kerogen, thus allowing accurate prediction of gas sorption, storage and diffusion properties in shales. Engineering and Physical Sciences Research Council (EPSRC)UK Research & Innovation (UKRI)Engineering & Physical Sciences Research Council (EPSRC) [EP/M000567/1]; EPSRCUK Research & Innovation (UKRI)Engineering & Physical Sciences Research Council (EPSRC) [EP/L022494/1, EP/R024790/1]; University of Nottingham We would like to thank Dr. Elisabeth Steer at Nanoscale & Microscale Research Centre for providing training in SEM-MLA and technician team (David Mee and Dr. Jacob Uguna) at the Faculty of Engineering, University of Nottingham for assistance with hydrofluoric acid digestion. Funding: Gas Adsorption Analysis Suit equipment funded by the Engineering and Physical Sciences Research Council (EPSRC, EP/M000567/1), FIB-SEM and TEM work was supported by the EPSRC (EP/L022494/1) and the University of Nottingham. A. Khlobystov acknowledges EPSRC for funding (Established Career Fellowship EP/R024790/1), C. Vane publishes with permission of the Executive Director, British Geological Survey (UKRI).

The use of interfacial layers to stabilize the lithium surface is a popular research direction for improving the morphology of deposited lithium and suppressing lithium dendrite formation. This work considers a different approach to controlling dendrite formation where lithium is plated underneath an interfacial coating. In the present research, a Li–Sn intermetallic was chosen as a model system due to its lithium-rich intermetallic phases and high Li diffusivity. These coatings also exhibit a significantly higher Li exchange current than bare Li thus leading to better charge transfer kinetics. The exchange current is instrumental in determining whether lithium deposition occurs above or below the Li–Sn coating. High-resolution transmission electron microscopy and cryogenic focused ion beam scanning electron microscopy were used to identify the features associated with Li deposition. Atomic scale simulations provide insight as to the adsorption energies determining the deposition of lithium below the Li–Sn coating.

In this study, three polymer precursor conformations, dilute, semi-dilute, and concentrated, were used to fabricate carbon molecular sieving (CMS) membranes via a fixed carbonization protocol. The effects of the precursor conformation on the microstructure of the resultant CMS membranes were characterized by Raman analysis. Their ability to separate light gases, such as H2/CH4 and H2/N2, was assessed with a single-gas system. Additionally, a novel method was proposed to detect the cutoff size of the CMS membranes created in this study. The method combined high-resolution transmission electron microscopy (HR-TEM) and a focused ion beam (FIB) system. Finally, due to the semi-dilute solution's denser polymer chains and lack of severe polymer entanglement, highly graphited CMS membranes with excellent gas separation performance were successfully synthesized using a semi-dilute polyetherimide dope solution. Interlayer distances in the carbon matrix were visualized and measured using our novel probing tool (HR-TEM and FIB) and software. The CMS membrane fabricated with a semi-dilute dope exhibited the best gas separation performance of the tested membranes. It had the most ordered carbon sheet orientation and exhibited a superior selectivity of H2/CH4 = 293 with a hydrogen permeability of 1138.7 Barrer, far surpassing the reported permselectivity of other membranes. We believe that the high H2/CH4 selectivity presented here is unprecedented for CMS membranes reported in the literature.

The mapping of the current induced by a focused electron beam in a scanning electron microscope (SEM) has been used to localize electrically stressed regions in the AlGaN/GaN-on-Si Schottky barrier diode (SBD) structures cross-sectioned by the focused ion beam (FIB) technique. We have shown that homogeneously distributed electron beam induced current (EBIC) intensity detected below the Schottky contact at 0 V changes with increasing reverse voltage ${V}_{R}$ and peaks at the edges of a field-plate region. The build-up of local microavalanches at high electric voltages has been indicated by overexposed EBIC signal at areas following the edges of the field plate structure. Interpretation of EBIC measurements is supported by electro-physical modeling and simulations employing the 2-D finite element method in Synopsys TCAD Sentaurus. The simulations prove that the electric field intensity in the SBD locally reaches values sufficiently high to trigger multiplication of the excessive carriers generated by an electron beam, which helps one to visualize and localize critical regions in GaN-based power electronic devices by the EBIC method.

Heterointerfaces with an epitaxial relationship, self-assembled nanocomposites of Pt(111)/CeO2(111) 60°, were successfully formed by simple oxidation of Pt5Ce alloy. Oxygen dissolution into the alloy causes spacial periodic compositional perturbation by atomic segregation, specifically, by local diffusion of Pt and Ce atoms. A striped pattern of Pt and CeO2 with a 4–5 nm periodicity formed through phase transformation of the Pt-rich alloy and oxidation of the Ce-rich alloy, respectively. Notably, a fully epitaxial relationship between the Pt and CeO2 phases was observed even in the initial stage. With continued annealing, the crystals rotated into an energetically favorable orientation with respect to the remaining (111)Pt//(111)CeO2. The alloy oxidation and its resulting nanoscale phase-separation behavior were verified in an ex situ annealing experiment of an alloy specimen, which had been first thinned by a focused ion beam. Changing the oxygen partial pressure to the reaction interface may alter the orientation relationship between the hexagonal close-packed Pt5Ce structure and face-centered cubic Pt/CeO2 structure, thereby altering the growth direction of the separated phases. These findings present a pathway for the self-assembly of epitaxial Pt(111)/CeO2(111) interface and are expected to assist the structural design of metal–oxide nanocomposites.

In this work we report the local growth of ordered arrays of 3D core–shell chiral nanohelices based on plasmonic gallium metal. The structures can be engineered in a single step using focused ion beam induced deposition, where a Ga+ ion source is used to shape the metallic nanohelix core, while the dielectric precursor is dissociated to create dielectric shells. The solubility of gallium in the different investigated dielectric matrices controls the core–shell thickness ratio of the nanohelices. The chiral plasmonic behaviour of these gallium-based nanostructures is experimentally measured by circularly polarized light transmission through nanostructure arrays and compared with numerical simulations. Large chiroptical effects in the visible range are demonstrated due to the plasmonic effects arising from gallium nanoclusters in the core.

Electrode/electrolyte interface plays a critical role in the performance and stability of solid oxide fuel cells (SOFCs). In the case of La0·6Sr0·4Co0·2Fe0·8O3-δ (LSCF) cathode, it is well known that cathodic polarization promotes the Sr segregation and diffusion towards the LSCF electrode and Y2O3–ZrO2 (YSZ) electrolyte interface, leading to the formation of SrZrO3 secondary phase and the disintegration of LSCF structure at the interface. On the other hand, LSCF is chemically stable with doped ceria electrolytes such as Gd-doped CeO2 (GDC). However, there appears no comparative studies on the intrinsic relationship between the surface segregation, interface reaction and stability of LSCF in YSZ and GDC electrolytes. Here, a comparative study has been carried out on the segregation and interface formation of LSCF on GDC and YSZ electrolyte under identical cathodic polarization conditions at 750 °C and 1000 mAcm−2 using focused ion beam and scanning transmission electron microscopy (FIB-STEM) techniques. Segregation of Sr occurs in the LSCF-GDC system, however, the inertness of GDC electrolyte suppresses the segregation process of Sr species. Instead, surface segregation of B-site Co cation becomes dominant under the cathodic polarization, forming isolated CoOx particles. The results indicate that the existence of chemical catchers such as Zr in the case of YSZ electrolyte for the segregated Sr species is kinetically the driving force for the Sr segregation and stability of LSCF electrodes under SOFC operation conditions.

Silicon carbide (SiC)-based ceramic matrix composites (CMCs) are utilized for their refractory properties in the aerospace industry. The composition and structure of these materials are crucial to maintaining the strength, toughness, oxidation, and creep resistances that are desired of silicon carbide. This work analyzes the chemical composition of the matrix in batches of SiC/SiC (silicon carbide fiber-reinforced silicon carbide matrix) minicomposites that are processed by chemical vapor infiltration of the BN interphase and SiC matrix on single Hi-Nicalon Type S fiber tows using a range of processing parameters. The analysis was performed here to investigate the potential causes of variation in matrix tensile strength in the various batches of minicomposites. Six different morphologies present in the silicon carbide matrix were observed: smooth, nodular, rough nodular, bumpy, nucleated, and plate-like. It was found that high-matrix tensile strength minicomposite batches contained solely the smooth morphology, while low-matrix tensile strength minicomposite batches contained a variety of other morphologies. FIB/TEM was used to study the atomic and crystal character of each individual morphology. Smooth SiC is oriented by the (111) planes and is primarily SiC, while the other morphologies are randomly oriented and contain significant oxygen. These results match the tensile strength tests, which pointed to smooth SiC as the strongest matrix material.

The feasibility of using selective thermal cobalt metal (Co) atomic layer deposition (ALD) as high density Cu–Cu interconnect bonding is demonstrated at a low temperature (200 °C) and with minimal surface pretreatment. A Cu/Gap/Cu structure, which emulates 3-D ICs stacking is fabricated. Cobalt ALD showing seamless interconnection between copper (Cu) pads with 30- $\mu \text{m}$ pitch is demonstrated with greater than 90% yield through electrical measurements, SEM inspection, EDS, and focused ion beam (FIB) cross section.

Iron-silica self-organized membranes, so-called chemical gardens, behave as fuel cells and catalyze the formation of amino/carboxylic acids and RNA nucleobases from organics that were available on early Earth. Despite their relevance for prebiotic chemistry, little is known about their structure and mineralogy at the nanoscale. Studied here are focused ion beam milled sections of iron-silica membranes, grown from synthetic and natural, alkaline, serpentinizationderived fluids thought to be widespread on early Earth. Electron microscopy shows they comprise amorphous silica and iron nanoparticles of large surface areas and inter/intraparticle porosities. Their construction resembles that of a heterogeneous catalyst, but they can also exhibit a bilayer structure. Surface-area measurements suggest that membranes grown from natural waters have even higher catalytic potential. Considering their geochemically plausible precipitation in the early hydrothermal systems where abiotic organics were produced, iron-silica membranes might have assisted the generation and organization of the first biologically relevant organics., Centro de Instrumentacion Cientifica (CIC) of the University of Granada, Spain, University of Granada, Spain, MINECO/FEDER MAT2017-87579-R MAT2016-81118-P, Junta de Andalucía FQM334, European Research Council under the Programme (FP7/2007-2013)/ERC 340863

While the application of focused ion beam (FIB) techniques has become a well-established technique in research and development for patterning and prototyping on the nanometer scale, there is still a large underused potential with respect to the usage of ion species other than gallium. Light ions in the range of m = 1–28 u (hydrogen to silicon) are of increasing interest due to the available high beam resolution in the nanometer range and their special chemical and physical behavior in the substrate. In this work, helium and neon ion beams from a helium ion microscope are compared with ion beams such as lithium, beryllium, boron, and silicon, obtained from a mass-separated FIB using a liquid metal alloy ion source (LMAIS) with respect to the imaging and milling resolution, as well as the current stability. Simulations were carried out to investigate whether the experimentally smallest ion-milled trenches are limited by the size of the collision cascade. While He+ offers, experimentally and in simulations, the smallest minimum trench width, light ion species such as Li+ or Be+ from a LMAIS offer higher milling rates and ion currents while outperforming the milling resolution of Ne+ from a gas field ion source. The comparison allows one to select the best possible ion species for the specific demands in terms of resolution, beam current, and volume to be drilled.

Optical liquid-crystal metasurfaces self-assemble on polymer layers locally processed with a digitally controlled focused ion beam. We expand their functionality by introducing superperiodic design...

In this study, a silver (Ag) coated copper (Cu) core–shell microparticles paste were fabricated and screen-printed on Polyimide (PI) substrates. It was sintered via intense pulsed light (IPL) sintering technique. IPL irradiation condition (i.e. pulse duration, irradiation energy) was optimized to obtain high conductivity and good oxidation resistance characteristics. To increase the packing density of the pastes and its oxidation resistance, Ag nanoparticles (Ag NPs) were added to Cu/Ag core–shell microparticles (core–shell MPs) paste with optimal mass ratio. To analyze the sintering and oxidation characteristics of hybrid pastes (Ag NPs + core–shell MPs), a scanning electron microscope (SEM) and a focused ion beam (FIB) was used. To demonstrate the mechanism of the sintering process on hybrid pastes, heat generation at the junctions between particles were simulated using Multiphysics COMSOL program. The packing density of the hybrid pastes was investigated using CATIA digital mock-up (DMU) program. In addition, to confirm the heat generation with respect to the packing density of the hybrid pastes, in-situ temperature monitoring process was conducted. As a result, hybrid paste pattern sintered with IPL showed excellent oxidation resistance (resistance increase rate in 300 °C for 5 h: 4.92%), and high electrical conductivity (6.54 μΩ cm).

For the first time, continuous layers of yttrium iron garnet (YIG, Y3Fe5O12) with a thickness of about 2 μm were synthesized on ferroelectric ceramic substrates based on lead titanate zirconate (PZT, PbZr0·45Ti0·55O3). The Y3Fe5O12 layer was deposited by ion-beam sputtering – deposition on PZT substrates of 400 μm thick by sputtering a polycrystalline target of the composition Y3Fe5O12 with a mixture of argon and oxygen ions. Due to preliminary planarization of the PZT surface with a TiO2 layer, a high-quality plane-parallel YIG/PZT interface was obtained, which is confirmed by scanning electron microscopy in combination with the focused ion beam technique. Atomic force microscopy showed that planarization makes it possible to achieve surface smoothness of 10 nm. The YIG/PZT heterostructures obtained in this work are potentially attractive for use in logic circuits based on low-scattering spin waves, memory elements, as well as electrically controlled microwave devices.

Niobium-based nanobridge superconducting quantum interference devices (SQUIDs) have shown very low noise performance and high-frequency operation. We describe how we are bringing together these two aspects of nanobridge SQUIDs with the aim of realizing single spin-flip detection using microwave inductive readout techniques, where the nanobridge SQUID is integrated into a superconducting coplanar waveguide resonator. Using electron beam lithography (EBL) is ideal for fabricating nanobridge junctions and has the advantage of being easily scalable compared to using a focused ion beam. In this article, we demonstrate that EBL is suitable for fabricating nanobridge junction SQUIDs, and they exhibit very comparable performance to previous focused ion beam milled SQUIDs. Our intrated devices show potential to be used for flux-tunable sensors.

Multilayer thin film systems on flexible polymer substrates are used as flexible optical solar reflectors or thermal insulation of satellites and spacecraft. During one year of operation, a satellite in low earth orbit typically encounters 6000 thermal cycles of ±100 °C. Due to the different coefficients of thermal expansion between the individual layers and the substrate it is important to investigate the thermo-mechanical stability of the multilayers as a function of the cyclic heat load. Scanning electron microscopy and focused ion beam cross-sectioning revealed that Inconel-Ag bilayers on fluorinated ethylene propylene (FEP) substrate severely degrade during thermal cycling of ±150 °C in a gaseous N2 atmosphere. After only 100 cycles through thickness cracks and subsurface voids in the Ag layer form as a result of equi-biaxial thermal stresses caused by the large difference in thermal expansion between film and substrate. Transmission Kikuchi Diffraction (TKD) before and after thermal cycling also revealed grain growth and twin widening in the Ag layer. Cracking and void formation are detrimental to application relevant material properties including corrosion protection (Inconel) and reflectivity (Ag). Reflectance measurements revealed that the amount of reflected energy as well as the reflection mode (specular vs. diffuse) significantly change during the first 100 cycles. Saturation of reflection characteristics was observed after 25 cycles, which correlates to a turning point in the evolution of Ag voids. Results of this study indicate that special focus should be directed towards thermal stress control (Δα) and tailoring of the metal-polymer interface to improve resistance of versatile metal-polymer systems against thermal cycling.

Mesoporous thin films (MTFs) displaying high surface area and controlled porosity constitute interesting materials for a plethora of applications in optics and electronics. A critical aspect in MTF processing is template removal that usually consists in thermal treatment at 350 °C, which consolidates the oxide film but might change the pore features. In addition, the use of such high temperature must be avoided when organic functionalities are to be preserved, or in the case of film deposition on polymeric substrates. Here we present and compare five different methods to consolidate silica MTF (SMTF) in mild conditions, at a maximum processing temperature of 130 °C. Conditions, such as duration of the thermal treatment, vacuum conditions, exposure to acidic and alkaline media, were systematically explored and the resulting films were analyzed by optical microscopy, focused ion beam, scanning electron microscopy, ellipsometry, and infrared spectroscopy. The optimized conditions leading to accessible mesopores and a stable oxide structure that can be used as a mesoporous perm-selective electrode are discussed.

Entrainment of the oxidized surface of a light alloy melt can result in the entrapment of a doubled-over surface oxide film containing a small quantity of the local atmosphere, forming an entrainment defect (also known as a double oxide film defect) in the final casting, which decreases the reproducibility of the casting. Most previous investigations into these defects were carried out on aluminum alloys, while research into these defects in Mg alloys has been relatively limited. The work reported herein aimed to characterize the behavior of entrainment defects formed in a Mg-Y alloy, under a cover gas of SF6/CO2. The entrainment defects were observed using scanning electron microscopy (SEM) and focused ion beam milling (FIB). A sandwich-like structure that likely corresponds to a deactivated entrainment defect, which has not been reported by previous publications, was discovered.

Summary Combined focused ion beam and scanning electron microscope (FIB‐SEM) tomography is a well‐established technique for high resolution imaging and reconstruction of the microstructure of a wide range of materials. Segmentation of FIB‐SEM data is complicated due to a number of factors; the most prominent is that for porous materials, the scanning electron microscope image slices contain information not only from the planar cross‐section of the material but also from underlying, exposed subsurface pores. In this work, we develop a segmentation method for FIB‐SEM data from ethyl cellulose porous films made from ethyl cellulose and hydroxypropyl cellulose (EC/HPC) polymer blends. These materials are used for coating pharmaceutical oral dosage forms (tablets or pellets) to control drug release. We study three samples of ethyl cellulose and hydroxypropyl cellulose with different volume fractions where the hydroxypropyl cellulose phase has been leached out, resulting in a porous material. The data are segmented using scale‐space features and a random forest classifier. We demonstrate good agreement with manual segmentations. The method enables quantitative characterization and subsequent optimization of material structure for controlled release applications. Although the methodology is demonstrated on porous polymer films, it is applicable to other soft porous materials imaged by FIB‐SEM. We make the data and software used publicly available to facilitate further development of FIB‐SEM segmentation methods. Lay Description For imaging of very fine structures in materials, the resolution limits of, e.g. X‐ray computed tomography quickly become a bottleneck. Scanning electron microscopy (SEM) provides a way out, but it is essentially a two‐dimensional imaging technique. One manner in which to extend it to three dimensions is to use a focused ion beam (FIB) combined with a scanning electron microscopy and acquire tomography data. In FIB‐SEM tomography, ions are used to perform serial sectioning and the electron beam is used to image the cross section surface. This is a well‐established method for a wide range of materials. However, image analysis of FIB‐SEM data is complicated for a variety of reasons, in particular for porous media. In this work, we analyse FIB‐SEM data from ethyl cellulose porous films made from ethyl cellulose and hydroxypropyl cellulose (EC/HPC) polymer blends. These films are used as coatings for controlled drug release. The aim is to perform image segmentation, i.e. to identify which parts of the image data constitute the pores and the solid, respectively. Manual segmentation, i.e. when a trained operator manually identifies areas constituting pores and solid, is too time‐consuming to do in full for our very large data sets. However, by performing manual segmentation on a set of small, random regions of the data, we can train a machine learning algorithm to perform automatic segmentation on the entire data sets. The method yields good agreement with the manual segmentations and yields porosities of the entire data sets in very good agreement with expected values. The method facilitates understanding and quantitative characterization of the geometrical structure of the materials, and ultimately understanding of how to tailor the drug release.

Angular dependences of the surface layer composition and the sputtering yield of silicon upon irradiation of the surface with a focused beam of gallium ions with an energy of 30 keV are obtained. The surface composition is analyzed by scanning Auger electron spectroscopy (SAES) and secondary ion mass spectrometry (SIMS). The sputtering yields are determined by measuring the volume of sputtering craters and irradiation doses. It is found that the content of gallium in the surface layer is about 30 at % with incidence angles close to the normal. With incidence angles greater than 30°, the concentration of gallium decreases quite sharply. The angular dependence of the sputtering yield of silicon does not correlate with the content of gallium in the surface layer and is rather well described by the cascade sputtering mechanism proposed by P. Sigmund.

There is no single methodology that can map the distribution of hydrogen and relate it to specific crystallographic phases or defect structures. Here, we present a case study demonstrating two methodologies towards achieving this goal: Correlating nanoscale secondary ion mass spectrometry (NanoSIMS) deuterium maps with electron backscattered diffraction (EBSD) data ahead of crack tips in a 304 stainless steel sample fatigue tested in deuterated water, and secondly correlating NanoSIMS deuterium maps with (scanning) transmission electron microscopy ((S)TEM) data from focused ion beam (FIB) lift-out samples. Correlating NanoSIMS/EBSD images, we confirmed an association of deuterium with martensitic lath structures. Furthermore, we discovered localized enrichments of deuterium along the martensitic laths, with a higher associative preponderance to e−martensite. Applying correlative NanoSIMS/(S)TEM imaging of the fracture surface, we found deuterium accumulation at the metal oxide interface. However, in the pre-crack region, the deuterium was clearly concentrated underneath the oxide layer.