bluuebunny/crossref_metadata_2025 huggingface dataset:
Segregation of Ba to Cr Thin Film and Glass Interfaces
Authors: Jiang N , Silcox J
Published: July 2020

The knowledge of interface properties is important in understanding the adhesion of metal films to glasses. To simplify the analysis, silicate glasses are usually regarded as amorphous SiO2. Comparing the measured energy loss functions of Code 7059 (BaO-B2O3-SiO2) and Code 1737 (Al2O3-B2O3-Si2) glasses by EELS with the calculated result of a-Si02 from optical data, this is a fairly good assumption in bulk materials. Depositing metals, which have strong affinity for oxygen on glasses, however, may result in minor elements, such as Ba in both 7059 and 1737 glasses, segregating to interfaces, and breaking down the chemical balance.

Figs. 1 and 2 show the EELS spectra acquired with a 2Å electron probe in Cr film, interface and bulk glass respectively. The Cr film in Fig. 1 was sputtered on 7059 glass at room temperature, and annealed at 450°C in compressed Ar gas for 10 min. The preparation of Cr thin film in Fig. 2 is mentioned elsewhere.
Statistical Analysis Of SEM-EDX Spectrum Images Of A Metal-Ceramic Braze
Authors: Kotula PG , Anderson IM , Stephens JJ
Published: July 2020

Spectrum imaging, where a complete spectrum is acquired at each pixel in an image, is potentially a very powerful technique for the characterization of materials. The primary challenge to overcome is to extract all of the relevant information from what are typically large data sets that cannot be readily visualized in their entirety. For energy-dispersive X-ray (EDX) spectrum images, simple mapping has typically been done. In this work, the application of multivariate statistical analysis (MSA) to the characterization of a metal/alumina braze by SEM-EDX spectrum images is described.

The braze characterized in this work joins polycrystalline alumina and a copper-silver eutectic alloy containing some titanium (an ‘active’ metal). The specimen geometry consisted of a sandwich of two pieces of alumina, two braze layers and a Kovar (primarily Fe, Ni and Co) filler layer in the middle. The entire assembly was heat-treated to bond the interfaces and then a polished cross-section was prepared.
Characterization and Production of Structurat Ceramics in the Systems Fe(1-X)O-Fe3O4 and MgO-MgFe2O4.
Authors: Huerta A , Ordoñez R , Calderon HA , Umemoto M , Tsuchiya K , Balmori H , Reguera E , Yee-Madeira H
Published: July 2020

Ceramic materials are widely studied for their high temperature structural applications. In many crystalline ceramics the range of solid solution decreases with temperature and thus precipitation of a second phase occurs. Thus, ceramics can be hardened by precipitation of second phases. However little is known regarding the effect of precipitation and nanocrystalline grain structure in the ductility of ceramic materials. On the other hand, oxide ceramics are under intense-investigation for their technological advantages in magnetization, dielectric response and chemical stability in such diverse uses as magnetic recording media, induction cores and microwave resonant circuits. This investigation has been undertaken to produce, characterize and measure the properties of ceramics that can be hardened by precipitation. The selected systems include Fe(1-x)O-Fe3 and MgO MgFe2O4. Mechanical milling is used to produce nanocrystalline ceramic oxides in the systems Fe(1-x)O-Fe3 and MgO-MgFe2O4 The mechanically alloyed powders are consolidated by means of spark plasma sintering (SPS) at temperatures ranging from 673 K to 1273 K and a pressure varying from 500 to 50 MPa in vacuum.
Wetting of Anorthite Liquid On m-Sapphire Substrates
Authors: Ravishankar N , Ramamurthy S , Schmalzried H , Barry Carter C
Published: July 2020

The equilibrium condition for a liquid droplet in contact with a smooth, homogeneous, isotropic, non-deformable surface is given by the celebrated Young-Dupre equation1. This equation is based on the balance of the horizontal forces acting on the droplet. The idealised assumptions involved in arriving at the equation are seldom met in real experiments. Recently, Saiz et al have discussed the case of ridging of the solid at the three phase boundary (solid-liquid-vapour boundary) as a requirement for a stable three-phase co-existence. The wetting of anorthite on. sapphire substrates of different orientations have been studied earlier. In the present study, the wetting of anorthite liquid on m-plane of sapphire has been studied. The m-plane of sapphire is known to reconstruct in to two sets of facets and thus provides an interesting opportunity to study the wetting of liquid on a nonsmooth surface which contains linear patches with different surface energies.
Microanalysis in the Development of Thermal-Sprayed Anodes for the Cathodic Protection of Reinforced Concrete Bridges.
Authors: Collins WK , Cramer SD , Covino BS , Govier RD , Holcomb GR , Bullard SJ , Laylor M
Published: July 2020

Microanalysis has proved crucial in developing thermal-sprayed metal coatings on the surface of reinforced concrete to serve as anodes in impressed current (ICCP) and galvanic (GCP) cathodic protection systems and in understanding their long-term performance. Corrosion of reinforcing bar in concrete bridges is the primary cause of structural deterioration in high chloride environments such as coastal locations and colder climates where roads are deiced with salt. Over 40 pet of more than 500,000 bridges surveyed in the U.S. are in need of repair or rehabilitation. Cathodic protections is the most effective method of mitigating the effects of corrosion due to chloride contaminated concrete. While a young technology, consumable thermal sprayed zinc anodes (see Figure 1 for a schematic of the process) totaling over 40,000 m2 (430,00 ft2) have been installed on the Oregon coast, primarily on the Depoe Bay, Yaquina Bay, and Cape Creek bridges.
High Resolution TEM of Post-Deposition Ion Implanted C-BN Films
Authors: Dolukhanyan T , Gunasekara S , Byon E , Lee SW , Lee SR , Sung C
Published: July 2020

Post-deposition ion implantation of boron nitride (BN) films is to be considered as a powerful method for improvement of adhesion between films and substrates and reduction of compressive stresses, which usually accompany the growth of cubic BN.

The goal of this investigation is microcharacterization of as-deposited and ion-implanted BN films to better understand effect of ion implantation on microstructure of the films and film/substrate interface. High Resolution TEM (HF-2000 with field emission gun) has been utilized because of nanocrystalline dimensions of both cubic (c-) and hexagonal (h-) BN phases.

BN films have been deposited on (100) oriented Si substrates by magnetically enhanced activated reactive evaporation2. Plasma source ion implantation has been performed to make surface modifications and to improve the adhesion of the films. X/S specimens for TEM and HRTEM have been prepared in a routine manner, using G-1 epoxy for coupling the specimens, Dimpler VCR D500I, and Gatan Precision Ion Polishing System for final thinning.
Microstructural Evolution in Al-Ti Multilayered Film with Annealing
Authors: Mitra R , Chiou WA , A.Madan  , Hoffman R , Weertman JR
Published: July 2020

There has been a significant interest in the development of dispersion-hardened aluminum for many years for high specific strength and modulus. Such materials are usually processed by powder or ingot metallurgy routes. In this study, Al3 Ti dispersion hardened Al was obtained by annealing Al-Ti multilayers. Al-Ti multilayered films have been characterized in the past by observing the structure of the layers, as well as tensile properties and hardness. This paper reports the structure of Al-Ti multilayers and the evolution of matrix and dispersoid microstructure on annealing.

The Al-Ti multilayered structures were prepared by magnetron sputtering using Al and Ti as targets and either Si (100) or NaCl as substrates. The bi-layer thickness was maintained around 16 nm with Ti constituting 12% of the total. The substrate was alternately moved below the Al and Ti targets for the purpose of deposition. The as-deposited film on the substrate and NaCl salts were annealed at 400°C for periods between 1 and 24 h in a vacuum (10−5 torr) furnace.
Interfacial Elemental Distribution In Tungsten Carbide Coated Steel
Authors: Naidu SV , Green Carlos , Maxie Christopher , Garber James D , Glass Gary A
Published: July 2020

Thermal spray of carbide coatings with high hardness and corrosion resistance onto steel substrates has technological importance. The adhesive strength is greatly effected by the interfacial impurities. Low porous and good quality 200 μm thick 86WC10Co4Cr coatings on 4140 steel are obtained by thermal spray methods using SC-HVOF gun at Cooper Oil Tools, Houston, TX. A Carl Zeiss DSM942 SEM with 3.5 nm resolution at 30 keV and Kevex LPX1 Super Dry Quantum Si(Li) Detector with < 145 eV resolution for Energy Dispersive X-ray Spectroscopy (EDXS) were used to study the elemental distribution across the interface. Fig. 1 shows the SEM micrographs of the interface between 86WC10Co4Cr thermal spray coating and 4140 steel substrate. The anchor patterns seen at the interface are believed to improve the adhesive qualities between the coating and the substrate.
Influence of Triple Junction Structure on Cu Segregation in Al Thin Films
Authors: Wauchope CJ , Keller RR , Sanchez JE
Published: July 2020

Al thin films, used as interconnects in integrated circuit devices, are subject to voiding failures due to electromigration and stress. Electromigration is a diffusion process and voids are known to form at points of flux divergence such as triple junctions. Void formation in Al-Cu films has also been associated with 9θ-phase (Al2 Cu) precipitates [1], which form preferentially at grain boundaries and triple junctions. Some triple junctions are favored as nucleation sites [2], presumably due to energetic differences arising from the crystallographic nature of the junctions. Their character can be calculated from the crystallographic orientations of the surrounding grains and the associated grain boundary dislocation networks [3]. Bollmann's method of analysis results in two categories of triple lines: I-lines - the special case where the grain boundary dislocations balance; and U-lines - the general case where the dislocation arrays do not balance. U-lines should have higher energies than I-lines and should therefore behave differently [3, 4]. This paper investigates the relationship between triple-line character and the location of Al2 Cu precipitates at certain triple junctions in Al-lCu thin films.
Determination of the Structure and Chemistry of Thermally Grown Oxides in Thermal Barrier Coatings
Authors: Brickey MR , Lee JL
Published: July 2020

Thermal barrier coatings (TBCs) insulate gas turbine hot section components from the hot (∽1200 - 1450°C) combustion gas exhaust stream. An airline company can save millions of dollars per year by using TBCs to protect vital engine components and to improve fuel efficiency. TBCs typically consist of an 8 wt.% yttria-partially-stabilized zirconia (YPSZ) ceramic topcoat deposited on a platinum-nickel-aluminide (Pt-Ni-Al) bondcoat covering a nickel-based superalloy substrate. Thermal exposure during YPSZ electron beam-physical vapor deposition (EB-PVD) and engine operation promotes the formation of a thermally grown oxide (TGO) between the Pt-Ni-Al and the YPSZ layers. Stresses can develop at the Pt-Ni-Al/TGO and TGO/YPSZ interfaces due to TGO growth and thermal expansion coefficient mismatch. These stresses eventually cause spallation of the YPSZ, leaving the metallic substrate vulnerable to high temperature degradation since exhaust temperatures are often higher than the melting temperature of most nickel-based superalloys (∽1200 - 1450°C).
Dislocation Substructure Contributions to the Tonal Qualities of the Caribbean Steel Drum - A TEM Study
Authors: Ferreyra E , Murr LE
Published: July 2020

Deformation substructures, especially dislocations, play an important role in the fabrication of the Caribbean steel drum and experimental evidence also suggests dislocations play a crucial role in the harmonic tuning and related musical qualities as well. In this study, we have examined and compared the dislocation substructures in high-quality, low-carbon (0.04-0.06 weight percent carbon) steel drum heads as manufactured, and sections cut from variously deformed (10% to 50% reduction) drum head sections, including those patterned with musical notes and heat treated; utilizing TEM.

We have recently shown that the requisite heating of a steel drum over a narrow temperature range (200 to 500°C) prior to tuning actually involves strain aging. Fundamentally, strain aging in steels has been explained by dislocation theory, but as far as we know, no experimental proof exists. This study also attempts to examine the more fundamental issues in strain aging, especially as it applies in the development of a high-quality, musical steel drum instrument.
Microstostructural Developments in Chill-Cast and Directionally Solidified Ti-44Al-11Nb Alloys
Authors: Menon ESK , Halladay TR , Fox AG , Mahapatra R
Published: July 2020

Studies aimed at improvements in the properties of titanium aluminides continue and efforts on optimizing the microstuctural parameters and a variety of processing techniques have attracted significant attention. In particular alloy compositions containing Ti-44to48at%Al and Nb as the major ternary addition (often with other minor alloying element additions) have been found quite promising. A fine fully lamellar structure in these TiAl-based intermetallic alloys has been reported to possess a combination of improved room temperature ductility, excellent fracture toughness, good oxidation resistance and creep properties. One of the serious problems associated with the TiAl-based alloys is the large grain size that develops in these alloys especially upon casting. A recent approach is to use directional solidification techniques in producing the TiAlbased alloys and it has been shown that desired orientations can indeed be produced by choice of suitable processing parameters.

In this study, we have examined the microstructural features associated with chill-cast as well as directionally solidified Ti-44at%Al-l lat%Nb alloy.
Microstructure of Laser Surface Melted Nickel Aluminum Bronze
Authors: Bennett JC , Hyatt CV
Published: July 2020

The copper alloys commonly referred to as nickel aluminum bronzes (NAB) are widely used in marine applications due to their excellent seawater corrosion resistance and good mechanical properties. Unfortunately, these alloys are susceptible to a variety of surface sensitive degradation processes such as cavitation and wear which significantly reduce service life. Laser surface melting and cladding techniques have recently demonstrated a potential to substantially enhance the performance of NAB components. This is associated with the occurrence of a martensitic or Widmanstätten transformation from the high temperature bcc β phase accompanied by precipitation of ordered intermetallic particles collectively referred to as κ. Optimization of these techniques requires an improved understanding of the evolution of microstructure in the NAB system under conditions of rapid solidification, however little data is currently available. In this paper, transmission electron microscopy is used to examine the microstructures of a series of laser surface melted NAB alloys containing from 8 to 12 wt. % Al, 3.8 to 6.5 wt. % Ni, 3.8 to 6.5 wt. % Fe, ∽1 wt. % Mn and, in some cases, lesser amounts of Ti or Zr.
New Transmission Electron Microscope Characterization Techniques from Precision Focused Ion Beam Membranes
Authors: Hull R , Dunn D , Demarest J , Mathes DT
Published: July 2020

The combination of focused ion beam (FIB) sputtering with transmission electron microscopy (TEM) offers new opportunities for the nanoscale characterization of materials. The FIB may be used to prepare membranes for TEM imaging which are: (i) Site selective, i.e. the membranes may be placed with sub-micron precision in all three dimensions, (ii) Largely free of differential sputtering artifacts, such that membranes may be prepared which are of constant thickness from structures with very dissimilar materials, and (iii) Of precisely known geometry.

The challenges associated with FIB specimen preparation will also be discussed and are summarized in Figure 1: (a) Surface amorphization damage, (b) Residual differential sputtering effects, (c) Redeposition of sputtered material and (d) Membrane bowing due to internal or beaminduced stresses. It will be demonstrated that each of these effects can be sufficiently controlled to allow high quality diffraction contrast imaging in a wide range of materials.
The FIB Lift-Out Specimen Preparation Technique for TEM Analyses and Beyond: SEM, AUGER, STEM, and SIMS Applications
Authors: Stevie FA , Vartuli CB , Mills RH , Irwin RB , Shofner TL , Giannuzzi LA
Published: July 2020

The use of focused ion beams (FIB) to prepare site specific specimens for transmission electron microscopy (TEM) and scanning electron microscopy (SEM) has been well documented. The 5 to 7 nm resolution on the latest FIB instruments has enhanced the ability to locate and expose features of interest. The use of the lift-out technique of FIB specimen preparation removes the need for prior thinning of the sample for TEM analysis and permits the study of materials that were difficult or impossible to do previously. Use of high current (10 nA) FIB instruments makes specimen preparation possible in less than one hour; automatic operation of FIB instruments will further reduce this time. After milling in the FIB, specimens are micromanipulated in air onto a 3 mm diameter TEM sample grid coated with carbon. The ability to analyze lift-out specimens using other analytical techniques that can take advantage of this site specific capability was previously suggested.
Precision FIB TEM Specimen Preparation ‘at a Distance’
Authors: Malis T , Buseck PR , Bradley JP , Li J , Phaneuf M
Published: July 2020

There is a trend in electron microscopy towards centralization of the more sophisticated EM systems. The rationale is that the techniques associated with such instrumentation are more efficiently practiced and developed by dedicated specialists in a regional or national centre surrounded by an extensive infrastructure. A similar argument can be used for the preparation of TEM specimens, especially as the demand grows for more precise location of the thin area to be examined. A new trio of techniques - tripod polishing, ultramicrotomy, and focused ion beam (FIB) thinning - can locate the thin area to within a micron or less. In the first two, a linear feature first located via light or scanning electron microscopy can be cross-sectioned by controlled material removal via mechanical polishing or diamond knife sectioning, respectively. With FIB, feature location and material removal are carried out in-situ, first imaging with a low intensity beam, then milling trenches on either side of the feature with a high intensity beam that is decreased as the feature is approached.
Transmission Electron Microscope Specimen Preparation of Metal Matrix Composites Using the Focused Ion Beam Miller
Authors: Cairney JM , Smith RD , Munroe PR
Published: July 2020

The focused ion beam (FIB) miller has been widely accepted as a powerful tool in the semiconductor industry. However, it is now finding applications in more general materials science applications. The high resolution, energetic gallium ion beam can rapidly and precisely section materials to reveal their internal structure; one particularly valuable application being the preparation of thin foils for TEM examination, especially from heterogenous materials.

To date, TEM sample preparation using FIBs has concentrated on semiconductor cross-sections [1], powders [2], and surface treated materials, e.g. galvanized steels [3]. However, thin foils of grossly heterogeneous materials, such as metal-matrix composites, are also difficult to prepare using conventional methods and are therefore well suited to sectioning using the FIB. In this study, thin foils were prepared from two composite materials: a 7075 aluminium alloy containing a 20% volume fraction of SiC particles and a FeAl alloy containing a 60% volume fraction of WC particles.
Effect of Surface Roughness on STEM Samples Prepared by FIB
Authors: Vartuli CB , Stevie FA , Kamino T
Published: July 2020

The Scanning Transmission Electron Microscope (STEM) can provide images beyond Scanning Electron Microscope (SEM) capability, on samples which do not have to be prepared to the degree required for Transmission Electron Microscopy (TEM). For some applications, such as semiconductor production, speed of analysis is critical. This paper explores Focused Ion Beam (FIB) sample preparation for STEM.

The samples were prepared using an Hitachi FB-2000A FEB tool. Two analysis regions of similar thickness were cut. The rough sample was milled using a 500 pA beam and no polish cut. The smooth sample was prepared by cutting first with a 500 pA beam, and then using additional, smaller diameter beams, concluding with a 30 pA beam. This resulted in a sample surface polished to a degree similar to that used for TEM specimens. The samples were imaged in an Hitachi HD-2000 STEM at 200KeV. Transmission electron images taken at 100 kx are shown in Figure 1 of the rough sample and of the smooth sample.
TEM FIB Lift-Out of Mount Saint Helens Volcanic Ash
Authors: Drown-MacDonald JL , Prenitzer BI , Shofner TL , Giannuzzi LA
Published: July 2020

Focused Ion Beam (FIB) specimen preparation for both scanning and transmission electron microscopy (SEM and TEM respectively) has seen an increase in usage over the past few years. The advantage to the FIB is that site specific cross sections (or plan view sections) may be fabricated quickly and reproducibly from numerous types of materials using a finely focused beam of Ga+ ions [1,2]. It was demonstrated by Prenitzer et al. that TEM specimens may be acquired from individual Zn powder particles by employing the FIB LO specimen preparation technique [3]. In this paper, we use the FIB LO technique to prepare TEM specimens from Mount Saint Helens volcanic ash.

Volcanic ash from Mount Saint Helens was obtained at the Microscopy and Microanalysis 1998 meeting in Atlanta. TEM analysis of the ash was performed using the FIB lift out technique [1]. Ash powders were dusted onto an SEM sample stud that had been coated with silver paint.
SEM Specimen Preparation by Broad Ion Beam Etching For Enhanced Channeling and Orientation Imaging
Authors: Alani R , P. Field D , Ogura K
Published: July 2020

It is well known that the “channeling contrast” and EBSD pattern formation, which is the basis for “orientation imaging microscopy” (OIM), is highly sensitive to specimen surface quality in SEM studies. Typically, specimens for these studies are prepared by a combination of mechanical grinding then chemical etching or electropolishing. As an alternative to the chemical step(s) in this technique, we report a method based upon broad ion beam etching equipment [1]. This alternative method is more universal and reliable for enhanced channeling contrast and EBSD/OIM of metallic materials.

A variety of polycrystalline metallic specimens were etched in an instrument dedicated for etching and coating SEM specimens [1] and examined in the SEM for channeling contrast and OIM mapping. Fig. la is a SEM image of an annealed titanium sheet specimen in as-received condition showing a well-defined surface texture. It can be seen that channeling contrast is absent, presumably due to the existence of a surface layer formed during the manufacturing process.
A Method for Site Specific Characterization Using a Dedicated FIB System Combined With an Analyitical TEM
Authors: Kamino T , Yaguchi T , Matsumoto H , Kobayashi H , Koike H
Published: July 2020

A method for site specific characterization of the materials using a dedicated focused ion beam(FIB) system and an analytical transmission electron microscope (TEM) was developed. Needless to say, in TEM specimen preparation using FIB system, stability of a specimen is quite important. The specimen stage employed in the developed FIB system is the one designed for high resolution TEM, and the specimen drift rate of the stage is less than lnm/min. In addition, FIB-TEM compatible specimen holder which allows milling of a specimen with the FIB system and observation of the specimen with the TEM without re-loading was developed. To obtain thin specimen from the area to be characterized correctly, confirmation of the area before final milling is needed. However, observation of cross sectional view in a FIB system is recommended because it causes damage by Ga ion irradiation. To solve this problem, we used a STEM unit as a viewer of FIB milled specimen.
Image Analysis and Fourier Transform Infrared Light Microscopy and Transmission Electron Microscopy of Mercerized Cotton Yarns
Authors: Boylston Eileen K
Published: July 2020

Renewed interest in mercerization as a pre-treatment for textile finishing has led to research on the effects of temperature on this process. Mercerization, the swelling of cotton in caustic soda, causes changes in crystallinity from a Cellulose I structure to a Cellulose II structure, along with changes in fiber physical dimensions, increased dyeability, luster and tensile strength. These changes are differentiated by light microscopy, image analysis and FT-IR, and transmission electron microscopy. Cotton yarns were mercerized with an aqueous solution of 23% NaOH and 1% wetting agent. The yarns were treated for 1 hour at 0, 20, 60, 80, and 110° C, and washed in distilled water at the same temperature as the treatment bath. Rapid embeddment procedures have been developed for analyzing the effects of treatments on cotton fiber structure. Cotton fiber cross-sections were prepared for light microscopy/image analysis by encasing the fibers in a tube,1 embedding in mefhacrylate plastic (Fig. la), polymerizing for 30 minutes with UV, and sectioning.
Effect of Specimen Aspect Ratio on the Reconstruction of Atom Probe Tomography Data
Authors: Larson D J , Russell K F , Miller M K
Published: July 2020

The field ion microscope is a point projection microscope, with the magnification inversely proportional to the radius of curvature (R) of the needle-shaped tip which comprises the specimen. The electric field at the specimen apex, which determines the trajectories of field evaporated ions, is given by F=V/(kR), where V is the specimen voltage and k is a geometric field reduction factor which increases with the specimen taper angle, θ. In the reconstruction of atom probe tomography (APT) data, the magnification, and thus the lateral extent of the analyzed region, is determined primarily by the specimen radius and taper angle. Asymmetric specimens may often be fabricated, even from materials which lend themselves to straightforward preparation. In addition, in certain materials, specimens with high aspect ratios may result from crystallographic preferential electropolishing. For accurate data reconstruction, it is important to know not only the specimen radius, but also, ideally, the degree of anisotropy (aspect ratio taper angle in orthogonal directions) of the specimen.
Electron Holography of Magnetic Memory Cells
Authors: Frost BG , Voelkl E , Kowalewski M
Published: July 2020

The phase shift of an electron wave compared with a reference wave amounts to [1]

where e is the electron charge (e > 0), h is Planck's constant, A is the magnetic vector potential, B is the magnetic induction and Фm is the magnetic flux through an area F bordered by the trajectories of the two waves. The absolute value of the vector F perpendicular to this area is given by F. As a simple example we qualitatively sketch the phase shifts by a uniformly magnetized sphere. The cross section of this sphere and the magnetic field lines are shown in Fig. 1. The electron wave travels perpendicular to the paper plane. On one side of the sphere the object wave through point 1 is compared with the reference wave through point 2 and on the opposite side the wave through point 3 is compared with the one through point 4.
Applications of Scanned Probe Microscopy in the Integrated Circuit Fabrication Industry
Authors: Richards J F , Kline RJ
Published: July 2020

Scanning Probe Microscopy (SPM), in particular Atomic Force Microscopy (AFM), has become well establish member of the IC metrology tool arsenal which few IC manufacturers are without. Although Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) remain the “workhorse” metrology techniques, SPM (standard AFM, as well as Scanning Capacitance Microscopy (SCM), Scanning Spreading Resistance Microscopy (SSRM), Scanning Kelvin probe, Nanoindentaion and others) are being increasingly called upon to help solve IC production problems and to aid in research and development for next generation devices.

Topographical metrology with standard AFM is by far the most common application of SPM in the semiconductor industry. It is typically used to gain surface roughness and grain size information about thin films that can be used as feedback to modify deposition conditions until the desired film properties are obtained.
Nanometer-Scale Dimensional Metrology With the Nist Calibrated Atomic Force Microscope
Authors: Dixson R , Köning R , Tsai V W , Fu J , Vorburger T V
Published: July 2020

Atomic force microscopes (AFMs), which generate three dimensional images with nanometer level resolution, are increasingly being used as tools for sub-micrometer dimensional metrology in a wide range of applications. Measurements commonly performed with AFMs are feature spacing (pitch), feature height (or depth), feature width (critical dimension), and surface roughness. To perform accurate measurements, the scales of an AFM must be calibrated regularly. Presently available standards for this purpose are calibrated using stylus instruments and optical techniques. The effectiveness of this approach, however, is limited by the differences in the working ranges of the various techniques and by questions of methods divergence. Such divergence may occur between measurements made by instruments using different techniques to measure the same feature. A reflected light microscope and an AFM, for example, may have differing sensitivity to the cross-sectional profile of measured lines. For sufficiently steep lines, an AFM tip will only contact the features near the tops.
Self-Assembled Monolayers: Assembling, Disassembling and Reassembling Studies Using Afm
Authors: Neves BRA , Salmon M E , Leonard DN , Russell PE , Troughton EB
Published: July 2020

Self-assembled monolayers (SAM) and multilayers of organic materials have been intensely studied in the past years, due to their numerous potential applications as, for example, lubricants, corrosioninhibitors and/or adhesion-promoters [1,2]. In this talk, we will present results of several studies carried out using Atomic Force Microscopy to investigate octadecylphosphonic acid (OPA) SAM deposited on mica. We have assessed various mechanisms of assembling, disassembling and reassembling the SAM on mica. The SAM deposition method employed in this work was drip coating using an OPA solution. We have used two different solvents, which exhibit very different OPA solubility, in this work: ethanol and trihydrofuran (THF). Regarding the assembling studies, we will show the formation of groups of OPA double-layers as the initial deposition stage (deposition time < 2 seconds) when using ethanol-based solutions. We will also show that annealing such samples at 60°C produces, favorably, OPA quadruple-layers, as shown in figures la and lb, respectively.
Identification of Halogen Atoms in Scanning Tunneling Microscopy Images of Substituted Phenyloctadecyl Ethers
Authors: Musselman I H , Lee H S , Iyengar S
Published: July 2020

Numerous scanning tunneling microscopy (STM) studies of organic adsorbates at the gas/solid and liquid/solid interfaces have been reported. Although early STM experiments of these systems were concerned primarily with visualizing molecules at the atomic level, the focus has shifted to extracting chemical information from STM images, including the identity of atoms or functional groups within an adsorbed molecule. However, STM image interpretation continues to be an immense challenge and one currently debated issue of critical importance is the mechanism(s) by which image contrast reveals atomic and molecular structure. Recently, a combination of electronic and geometric factors was proposed. The electronic factor addresses the coupling between the energy levels of the adsorbate and the Fermi level of the surface whereas the geometric factor is related to the spatial overlap between the STM tip and the functional group.

A study in our laboratory of a homologous series of para-halogenated phenyloctadecyl ethers (XPOEs, where X = H, Cl, Br, I) adsorbed on highly oriented pyrolytic graphite (HOPG) has contributed significantly to the understanding of the image contrast mechanism for molecular adsorbates and of the chemical specificity of STM.
Scanning Probe Microscope Studies of Nanoscale Corrosive Wear of Single Crystal Surfaces
Authors: Thomas Dickinson J
Published: July 2020

In a number of situations and applications, the tribological wear of ceramic and minerallike surfaces is often greatly enhanced in the presence of a corrosive fluid. Examples are the wear of surfaces associated with joints (biomaterials) subject to and the extremely active application to high density circuit production which requires chemical mechanical polishing (CMP). The physics and chemistry of these enhanced wear rates are needed to reduce wear and to improve and extend CMP to new applications. In both situations, surfaces experience simultaneous tribological loading and corrosive chemical exposure, which together produce high wear rates and altered topography. In CMP, the goal is to efficiently achieve very flat surfaces. As feature sizes diminish further, it is conceivable that atomically flat surfaces will be necessary. In almost all tribological situations, it is the interaction of asperities, often micron and sub-micron in dimensions, that control the wear processes due to the high stresses associated with these small structures.
Development of a Combined Scanning Ion-Conductance and Nearfield Optical Microscope to Image Living Cells
Authors: Raval M , Klenerman D , Rayment T , Korchev Y , Lab M
Published: July 2020

It is important to be able to image biological samples in a manner that is non-invasive and allows the sample to retain its functionality during imaging.

A member of the SPM (scanning probe microscopy) family, SNOM (scanning near-field optical microscopy), has emerged as a technique that allows optical and topographic imaging of biological samples whilst satisfying the above stated criteria. The basic operating principle of SNOM is as follows. Light is coupled down a fibre-optic probe with an output aperture of sub-wavelength dimensions. The probe is then scanned over the sample surface from a distance that is approximately equal to the size of its aperture. By this apparently simple arrangement, the diffraction limit posed by conventional optical microscopy is overcome and simultaneous generation of optical and topographic images of sub-wavelength resolution is made possible. Spatial resolution values of lOOnm in air and 60nm in liquid[1,2] are achievable with SNOM.
Atomic Force Microscopy of Industrial Polymers
Authors: Galuska Alan A
Published: July 2020

The performance of many industrial polymers is determined by the microscopic morphology of the polymers. For example, surface morphology can influence properties such as adhesion, friction, sealing, blocking, printability, wettability, and haze. Furthermore, bulk morphology often controls mechanical properties such as toughness. strength, wear, and tear resistance. In order to optimize polymer performance, quick reliable methods of determining surface and bulk morphology are essential.

In the past, electron microscopy (in particular TEM) has been the primary method for determining polymer morphology. However, the usefulness of electron microscopy has been limited by the destructive nature of the electron beam, the naturally poor contrast between polymer types, and the difficulty in preparing (staining, etching, cryogenic ultramicrotoming, etc.) high quality specimens.

Recently, the tapping phase-shift mode of atomic force microscopy (TPSAFM) has provided the polymer scientist with a simple, quick, flexible and quantitative method for determining polymer surface and bulk morphology.
Nanomechanical Property Determination of Organic Matrix in Mollusc Shell Nacre: A Biocomposite
Authors: Sopp Jeffrey M , Sarikaya Mehmet
Published: July 2020

Mechanical properties were determined from the organic matrix of a mollusc hard tissue using a nanomechanical testing instrument attached to an atomic force microscope (AFM). Shells of molluscs are two-tier functionally-gradient ceramic/polymer biocomposites used by organisms as impact resistant materials. The inner section of the red abalone (Haliotis refuscens)shell, nacre (mother-ofpearl), has a brick and mortar microarchitecture with pseudo-hexagonal-shaped bricks made of aragonitic (orthorhombic) CaCO3 platelets (0.25 μn thick, and 5 μm edge length) surrounded by a thin (10-25 nm thick) proteinaceous organic matrix (Fig. 1). This higly ordered biocomposite has submicron-layered structure that result in excellent bulk mechanical properties, not achieved by manmade composites with similar phase compositions and, therefore, offers biomimetic lessons for novel materials design. In this model biomimetic composite, mechanical properties of its constituents need to be evaluated in addition to the details of the microstructure. We previously determined nanomechanical properties (hardness and modulus) of individual (twinned, single crystalline) aragonitic platelets.
Morphology and Film Properties of Composite Carboxylated Latexes
Authors: Shaffer O L , Sandor M W , El-Aasser M S
Published: July 2020

In industrial applications, such as paints or adhesives, composite latex particles are very common. Most of the properties which are obtained from composite latexes and their films cannot be achieved by physical blending of different polymer components. Therefore it becomes crucial to examine the morphology of composite latexes formed by a multiple-stage polymerization process. The latexes for this study have been examined by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Various staining methods were used such as ruthenium tetroxide (RuO4), cesium hydroxide (CsOH), and uranyl acetate (UAc) as a negative stain.

The poly(n-butyl acrylate/ poly(methylmethacrylate) (PBA/PMMA) composite latex particles consist of a soft core phase and a hard second phase with varying amounts of acrylic acid in the core, the shell and in both core and shell. The latexes were examined before and after cleaning by a centrifugation technique with 100,000 molecular weight filters.
Polymer Characterization Using Confocal Scanning Laser Microscopy: A Review
Authors: Atkinson Matthew R
Published: July 2020

Confocal microscopy was developed in 1957 by Minski, who was awarded a patent for this work in 1961. Since that time many advances have been in new designs and implementations. There are two basic classes of confocal microscope: the Nipkow-disk-based confocal microscope which allow real-time direct viewing of the sample, and the confocal scanning laser microscopes (CSLM). The CSLM will be focussed on in this presentation.

The CSLM scans a focussed beam over, across or through the sample, collecting the reflected, scattered or emitted light. This light is directed towards an optical spatial filter, which passes light returning from the on-axis focus position, and rejects light that is returning from anywhere else. By detecting the light passing through the spatial filter synchronously with the moving beam and/or sample, an image that has only in-focus information is acquired. Typically a set of images is acquired as the sample is moved through focus: from this “image stack” both an extended-focus image and topographic information can be obtained.
FTIR Imaging of Multiphase Polymer Systems
Authors: Wall BG , Koenig JL , Bhargava R , Snively CM
Published: July 2020

Fourier Transform Infrared (FTIR) Microspectroscopy is a powerful method to examine and characterize domains down to areas of 10х10 μm2. Spatial concentration maps of chemical species were obtained using apertures to sequentially examine areas on a grid and obtain a map by plotting average spectral absorbance data obtained from each of the areas. New Focal Plane Array (FPA) detectors, composed of a large number (in our case, 64х64) of small detectors arranged in a grid pattern, allow simultaneous collection of infrared radiation at many points from a large spatial region (500х500 μm2 in our case). This allows for a rapid acquisition of chemically specific images from a given area and the examination of several real-time processes. This technique has found a wide variety of applications in multi-phase polymers including polymer laminates, phase separated polymer composites, semi-crystalline polymers and blends, and solvent diffusion into polymers have been the main areas of interest in non-biological IR studies using FPA detection. We present some of the recent work in our group on various multi-phase polymer systems using FPA based infrared spectroscopy.
In Vitro Studies of Microtubule Structures Using the Mac Mode AFM
Authors: Zhu J , Hartman J , Case R , Rice S , Vale R
Published: July 2020

Microtubules are long, hollow, stiff polymers that extend throughout the cytoplasm. They are involved in such diverse functions as governing the location of membrane-bounded organelles and chromosome separation during mitosis. The basic structural unit is tubulin, which is a heterodimer consisting of two closely related and tightly linked globular polypeptides called α and β-tubulin. Alternating α and β tubulin subunits form protofilaments, 13 of which bundle around a central core to form microtubule. The detailed structures of cytoplasmic microtubules have been studied extensively using various electron microscopic techniques. As microtubules are dynamic structures in constant transitions between growing and shrinking phases, it would be extremely interesting to investigate the structural organization of the subunit tubulin molecules in a buffer close to physiological conditions. With its high resolution and ability to image in fluid, atomic force microscope (AFM) makes it possible to study the biological structures in a native environment.
Probing Biomaterials with the Atomic Force Microscope
Authors: Hansma Helen G , Chen Christine , Golan Roxana , Pietrasanta Lia , Sorenson Cody , Auerbach Ilene , Holden Patricia
Published: July 2020

Recent AFM research in our laboratory has covered such diverse biomaterials as laminin and other macromolecules from basement membranes (Fig. 1) (1), DNA condensed for gene therapy (Fig. 2) (2), DNA-protein complexes in the yeast kinetochore (Fig. 3) (3), and biofilms of the bacterium Pseudomonas putida (Fig. 4) (4).

Laminin is a major protein of basement membranes. When analyzed by AFM in air, it shows a variety of conformations of its cruciform structure (Fig. 1A). Time-lapse images of a single laminin molecule in aqueous solution show the flexibility of the laminin arms as they move and bend (Fig. 1B)(1).

AFM analysis of DNA condensed for receptor-mediated gene therapy poses a puzzle (Fig. 2)(2). Polylysine condenses DNA poorly (Fig. 2A), while AsOR-polylysine condenses DNA into compact toroids and short rods (Fig. 2B). AsOR (asialoorosomucoid) is a 38-kDa glycoprotein with a net negative charge of 5 carboxylic acid groups per molecule. The puzzle is why this negative glycoprotein, covalently attached to polylysine, can enhance the condensation of DNA so much over the condensation caused by the polycation, polylysine, alone.
Gel-Immobilized Microarrays for the Study of Nucleic Acids and Proteins
Authors: Zlatanova Jordanka , Mirzabekov Andrei
Published: July 2020

Recently, a quantum leap has been achieved in the analysis of DNA and proteins through the advent of the biochip technology. This technology is a product of a broad interdisciplinary approach combining biochemical analysis, semiconductor manufacturing and computer software. Biochips can be defined as miniaturized ordered arrays of macro molecules or pieces thereof that are immobilized in a precise spatial manner on support media and can be used in highly automated, large-scale and high-throughput fashion to analyze biological material. The biochip can be used in a wide variety of areas related to basic research and can find versatile applications in almost all areas of human activities connected to biotechnology, medicine, agriculture, and environment monitoring and bioremediation.

The power of the technology has already been demonstrated in areas like gene sequencing and proofreading, detection of single-nucleotide mutation and polymorphism, identification of genes, identification of viruses and microorganisms, gene expression analysis, analysis of sequencespecific ligands and proteins, and others.
Transport of Connexins and Gap Junction Turnover in Living Cells Visualized Using Green Fluorescent Protein Tagged Connexins.
Authors: Laird DW , Jordan K , Fistouris P , Solan JL , Lampe PD , Shao C
Published: July 2020

Connexins oligomerize into hemichannels, traffic to the cell surface and dock with hemichannels from an adjacent cell to form intercellular gap junction channels. Pulsechase studies have revealed that connexins are subject to a short half-life ranging from 1- 5 hrs. To examine the mechanisms involved in connexin trafficking, gap junction assembly and internalization in living cells we fused green fluorescent protein (GFP) to the amino or carboxyl terminus of full length connexins (Cx). When cDNA encoding Cx43-GFP was transfected into communication-competent NRK cells, Cx43-negative MDCK cells, or communication-deficient Neuro2A or HeLa cells, the fusion protein of predicted length was expressed, transported, and assembled into functional gap junctions (Figure 1). Most notably, the fusion of GFP to the amino terminal of Cx43 (GFP-Cx43) or Cx32 (GFP-Cx32) did not inhibit the co-translational insertion of these polytopic type IV connexins into the membrane and as a result gap junction plaques assembled at cellcell interfaces.
Clathrin-Mediated Endocytosis in the Giant Reticulospinal Synapse in Lamprey
Authors: Shupliakov O
Published: July 2020

The chemical synapse is a key structure used by neurons to communicate with neighboring cells. This is an asymmetric structure composed of two elements. The presynaptic part contains small synaptic vesicles filled with neurotransmitter. In an active synapse synaptic vesicles fuse with the presynaptic membrane and release neurotransmitter into the synaptic cleft. This results in activation of receptor molecules and respective ion channels on the postsynaptic cell. After a fusion event, the vesicle membrane is retrieved to form a new vesicle. Clathrin-mediated endocytosis is one of the main pathways for synaptic vesicle recycling. It involves a series of steps that starts with a flat plasma membrane and ends with an internalized coated vesicle. Four distinct stages have been defined: (1) the assembly of the clathrin coat, (2) the invagination of the coated membrane into a pit, (3) the constriction of the coated pit, and (4) the fission reaction that liberates the coated vesicle (e.g. De Camilli and Takei, 1996; Brodin et al., 1997). Analysis of mutant yeast and animal cells have linked a number of proteins to each of these stages. Taken together with data from in vitro binding studies, these observations indicate the existence of a complex molecular network that regulate the endocytic reactions.