Field-emission Type Scanning Electron Microscope Research Articles

Ferromagnetic Resonance Spectroscopy and Rock Magnetic Characterization of Fossil Coral Skeletons in Ishigaki Islands, Japan

Skeletons of hermatypic corals (e.g., Porites) might have enormous potential as a high-resolution paleomagnetic recorder owing to their rapid and continuous growth over hundreds of years at a rate of up to 2 cm/year, although typical corals show an extremely weak intensity of remanence and low stability. We found that coral tsunami boulders with negligible amounts of calcite on Ishigaki Island show a measurable intensity of remanence; thus, we attempted to characterize the magnetic assemblages in this coral skeleton to determine whether it is of biogenic or detrital magnetite using first-order reversal curve (FORC) measurements, ferromagnetic resonance (FMR) spectroscopy, and petrological observations through field-emission type scanning electron microscope (FE-SEM) with an acid treatment. The FMR derivative spectra of coral skeleton samples represent multiple derivative maxima and extended low-field absorption, indicating the presence of intact biogenic magnetite chains. FORC diagrams represent a “central ridge” signature with a vertical spread. These FMR and FORC features indicate the magnetization of these coral skeletons that are mainly created using intact biogenic magnetites and mixtures of grains from collapsed biogenic magnetites, pseudo-single domain grains, and multi-domain grains such as detrital magnetite. FE-SEM observations confirm the presence of a chain-like structure of iron oxides corresponding to the features of biogenic magnetite. Therefore, the magnetic mineral assemblage in coralline boulders from Ishigaki Island consists of dominant biogenic-origin single-domain magnetite and a trace amount of detrital component, indicating that fossil coral skeletons in Ishigaki Island have potential for utilization in paleomagnetic studies.

Silver Nanoscale Hexagonal Column Chips for Detecting Cell-free DNA and Circulating Nucleosomes in Cancer Patients.

Blood tests, which are commonly used for cancer screening, generally have low sensitivity. Here, we developed a novel rapid and simple method to generate silver nanoscale hexagonal columns (NHCs) for use in surface-enhanced Raman scattering (SERS). We reported that the intensity of SERS spectra of clinical serum samples obtained from gastrointestinal cancer patients is was significantly higher than that of SERS spectra of clinical serum samples obtained from non-cancer patients. We estimated the combined constituents on silver NHCs by using a field emission-type scanning electron microscope, Raman microscopes, and a 3D laser scanning confocal microscope. We obtained the Raman scattering spectra of samples of physically fractured cells and clinical serum. No spectra were obtained for chemically lysed cultured cells and DNA, RNA, and protein extracted from cultured cells. We believe that our method, which uses SERS with silver NHCs to detect circulating nucleosomes bound by methylated cell-free DNA, may be successfully implemented in blood tests for cancer screening.

Field emissions of graphene films deposited on different substrates by CVD system

Graphene films are deposited on copper (Cu) and aluminum (Al) substrates, respectively, by using a microwave plasma chemical vapour deposition technique. Furthermore, these graphene films are characterized by a field emission type scanning electron microscope (FE-SEM), Raman spectra, and field emission (FE) I–V measurements. It is found that the surface morphologies of the films deposited on Cu and Al substrates are different: the field emission property of graphene film deposited on the Cu substrate is better than that on the Al substrate, and the lowest turn-on field of 2.4 V/μm is obtained for graphene film deposited on the Cu substrate. The macroscopic areas of the graphene samples are all above 400 mm2.

Synthesized silicon-substituted hydroxyapatite coating on titanium substrate by electrochemical deposition

Silicon-substituted hydroxyapaptite (Si-HA) coatings were prepared on titanium substrates by electrolytic deposition technique in electrolytes containing Ca(2+), PO(4)(3-) and SiO(3)(2-) ions with various SiO(3)(2-)/(PO(4)(3-) + SiO(3)(2-)) molar ratios (η(si)). The deposition was all conducted at a constant voltage of 3.0 V, with titanium substrate as cathode and platinum as anode, for 1 h at 85°C. The coatings thus prepared were characterized with inductively coupled plasma (ICP), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), field-emission-type scanning electron microscope (FSEM). The results show that the silicon amount in the coatings increases linearly to about 0.48 wt% at first with increasing η(si) between 0 and 0.03, then increases slowly to about 0.55 wt% between 0.03 and 0.10 and finally maintains almost at a level around 0.55 wt% between 0.10 and 0.30. The tree-like Si-HA crystals are observed in the coatings prepared in the electrolyte of η(si) = 0.20. And the presence of silicon in electrolytes decreases the thickness of the coatings, with effect being more significant as η(si) increased. Additionally, the substitution of Si causes some OH(-) loss and changes the lattice parameters of hydroxyapatite (HA).

Partitioning of iron between perovskite/postperovskite and ferropericlase in the lower mantle

The Fe2+‐Mg distribution coefficients (KD) between perovskite/postperovskite and ferropericlase were determined in a (Mg0.9Fe0.1)2SiO4 bulk composition. High‐pressure and high‐temperature experiments were carried out between 36 and 128 GPa and 1760–2170 K in a laser‐heated diamond anvil cell (LHDAC). Chemical analyses were made on recovered samples with transmission electron microscope (TEM) and field‐emission‐type scanning electron microscope (FE‐SEM). All the samples exhibited a strong heterogeneity in iron content caused by relatively large temperature gradient during laser‐heating, being depleted at the center of the hot spot and enriched at the margin. The KD values measured from coexisting perovskite/postperovskite and ferropericlase showed apparently very large variation in each sample, which could be the source of considerable discrepancy among previous measurements of KD using the LHDAC techniques. Nevertheless, the data obtained from a specific portion of the sample that retained the original bulk composition may represent the equilibrium partitioning. Present results demonstrate that the iron partitioning between perovskite/postperovskite and ferropericlase changes little at a given temperature throughout the lower mantle pressures. Both electronic transition of iron and postperovskite phase transition have small effects on iron partitioning.

Field emission characteristics of nano-structured carbon films deposited on differently pretreated Mo films

Nano-structured carbon films (NCFs) were grown on Mo layers by microwave plasma chemical vapor deposition (MPCVD) system. The Mo layers were deposited on ceramic substrates by electron beam deposition method and were pretreated by different techniques, which include ultrasonically scratching and laser-grooving technology (10 line/mm). NCFs were characterized by a field emission type scanning electron microscope (FE-SEM), Raman spectra and field emission (FE) I– V measurements. Effects of process parameters on morphologies, structures and FE properties of NCFs were examined. The experimental results show that two kinds of NCFs deposited at the same parameters employed for the MPCVD process were respectively composed of carbon nano-balls and reticular carbon nano-tubes inlayed by carbon nano-balls with dissimilar disorder structures, both NCFs showed each merits and exhibited good field emission properties, especially shown in the uniformity of FE, the uniform field emission images with areas of 4 cm 2 were obtained. Growth mechanism influenced by different pretreated method was discussed and the possible FE mechanisms of the NCFs were also investigated. Finally, the process characteristics of laser-grooving technology were analyzed, and its potential applications were predicted.

1210 SiN薄膜の引張・曲げ強度特性に及ぼす微小欠陥の影響(S05-3 ナノ・マイクロ材料の強度・信頼性(3)ナノ・マイクロ材料の強度物性評価,21世紀地球環境革命の機械工学:人・マイクロナノ・エネルギー・環境)

The mechanical properties of SiN thin film microelements, fabricated by sputtering and CVD processes, were evaluated using specially designed testing systems for the mechanical properties of thin tensile and bending microelements. The tensile testing system consists of a tensile testing machine actuated by a PZT driven positioning stage, a micro manipulation system, and a non-contact strain measurement system with a help of a double-filed-of-view microscope. For bending tests, the testing system used is based upon a Nano Indenter with a specially designed indenter and an ultra-precise positioning stage. In order to investigate the size effects on the mechanical properties, the thickness of the sample used were 1μm and 3μm, and the specimen width was varied from 5μm to 50μm. The Young's modulus of the SiN thin film was independent of sample width and thickness: the Young's modulus was not influenced by specimen size and loading mode. However, Young's modulus of the film fabricated by sputtering was higher than that by CVD. The tensile strength and bending strength increased with a decrease in thickness, and the strength of the film fabricated by CVD was higher than that by sputtering. The fracture initiation sites were closely examined by a high-resolution field-emission type scanning electron microscope, and the strength of the thin film was revealed to be determined by stress intensity factor of the micro defect in a thin microelement.

Growth mode and electronic structure of Au nano-clusters on NiO(0 0 1) and TiO 2(1 1 0)

The growth mode and electronic structure of Au nano-clusters grown on NiO and TiO 2 were analyzed by reflection high-energy electron diffraction, a field-emission type scanning electron microscope, medium energy ion scattering and photoelectron spectroscopy. Au was deposited on clean NiO(0 0 1)-1 × 1 and TiO 2(1 1 0)-1 × 1 surfaces at room temperature with a Knudsen cell at a rate of 0.25–0.35 ML/min (1 ML = 1.39 × 10 15 atoms/cm 2:Au(1 1 1)). Initially two-dimensional (2D) islands with thickness of one Au-atom layer grow epitaxially on NiO(0 0 1) and then neighboring 2D-islands link each other to form three-dimensional (3D)-islands with the c-axis oriented to the [1 1 1] direction. The critical size to form 3D-islands is estimated to be about 5 nm 2. The shape of the 3D-islands is well approximated by a partial sphere with a diameter d and height h ranging from 2.0 to 11.8 nm and from 0.95 to 4.2 nm, respectively for Au coverage from 0.13 to 4.6 ML. The valence band spectra show that the Au/NiO and Au/TiO 2 surfaces have metallic characters for Au coverage above 0.9 ML. We observed Au 4f spectra and found no binding energy shift for Au/NiO but significant higher binding energy shifts for Au/TiO 2 due to an electron charge transfer from Au to TiO 2. The work function of Au/NiO(0 0 1) gradually increases with increase in Au coverage from 4.4 eV (NiO(0 0 1)) to 5.36 eV (Au(1 1 1)). In contrast, a small Au deposition(0.15 to 1.5 ML) on TiO 2(1 1 0) leads to reduction of the work function, which is correlated with an electron charge transfer from Au to TiO 2 substrate.

Structural Control of Micro-Pore Surface and Trihalomethanes Adsorption Ability of Phenol Activated Carbon

The purpose of this study was to improve the adsorption ability of activated carbon for removal of trihalomethanes (THMs) to design a small and efficient water purifier. The phenol activated carbon with the high adsorption ability to THMs was used in the experiment. To improve the adsorption ability of the activated carbon, the effect of heat treatment temperature under the nitrogen atmosphere was investigated. The effect of the heat treatment temperature was evaluated from the chloroform adsorption isotherm, and the amount of purified water containing THMs. First of all, phenol resin was carbonized at 600°C for 3 h, and was activated by steaming at 900°C. Activation time was 0.5, 1.0, and 2.5 h. Next, the heat treatment was carried out for the sample of 1.0 h activation with the highest adsorption ability. The heat treatment temperature was 450, 600, 750, and 900°C. The heat treatment time was fixed at 3 h for all samples. As a result, it was found that the adsorption ability of the phenol activated carbon to THMs raised by about 1.6 times with the heat treatment at 750°C following the activation. On the other hand, the influence of the heat treatment on the structure of the phenol activated carbon was investigated. The structure was analyzed with pore size distribution measurement, X-ray photoelectron spectroscopy (XPS), temperature programmed desorption mass spectrometry (TPD-MS), and field emission-type scanning electron microscope (FE-SEM). The elimination of functional groups were observed clearly with the heat treatment, which means increased hydrophobicity of pore surface in the phenol activated carbon. Moreover, enlargement of the pore entrance were confirmed. Therefore, we concluded that THMs were efficiently led into pores due to the enlarged pore entrance, and was adsorbed strongly due to the increased hydrophobicity.

Field Emission-Type Scanning Electron Microscope for Examination of Irradiated Fuels

A field emission-type scanning electron microscope (FE-SEM) for observation of irradiated fuels and materials was installed at the Reactor Fuel Examination Facility at the Japan Atomic Energy Research Institute. A cell with remote-handling systems only for the FE-SEM was made to enable safe manipulation of highly radioactive samples. Some parts of the FE-SEM were modified for the remote handling outside the cell. The energy dispersive spectrometer modified for the samples was also equipped on the FE-SEM to determine element compositions of the observed samples. After the modifications, characterization tests were carried out using deposited gold film and uranium rock samples that were unirradiated. In results of the tests, high-resolution images of those specimens were obtained with high magnification above 10 000. From those results, it was expected that the FE-SEM kept the high performance even after the modifications and would be utilized for radioactive samples.

Development of Observation Method for Tempered Martensite Microstructure Using Chemical Mechanical Polishing Technique

A new observation method was developed for visualizing microstructure on a chemical mechanically polished (CMP) surface for tempered martensite of JIS-SCM440, a medium-carbon steel. The CMP and an electropolished (EP) surfaces were observed using an atomic force microscope (AFM) and a field emission type-scanning electron microscope (FE-SEM), respectively. AFM images, FE-secondary and backscattered electron images and electron backscattered patterns (EBSP) were obtained for the CMP and EP surfaces. The AFM and FE-secondary electron images of the EP surface clearly visualized martensite blocks and cementite particles, since unevenness corresponding to blocks and cementite particles was created by electropolishing. On the other hand, the AFM images of the CMP surface revealed that the CMP process produced a very smooth surface with unevenness not exceeding 10 nm. The FE-backscattered electron images of the CMP surface only visualized the crystal misorientation of the martensite matrix microstructure, since the images are not influenced by surface unevenness. The CMP surface is more appropriate than the EP surface for EBSP measurements, since the CMP surface is smoother than that of the EP surface. Blocks with a high-angle boundary exceeding 15° could be recognized by EBSP mapping, but laths with a low-angle boundary below 3° could not.

TOF-SIMS measurement for the complex particulate matter in urban air environment

We developed the measurement method for the complex particulate matter in urban air environment using micro-beam analyses [electron probe microanalysis (EPMA), field emission type scanning electron microscope (FE-SEM), and TOF-SIMS]. In this study, the environmental particles collected at the location near both the traffic route and the railroad were characterized. By the EPMA analysis and FE-SEM observation, it became clear that many iron particles adsorbed smaller environmental particles on surface. The most of adsorbed particles were the carbonaceous particles containing small amount of silicon, as observed from the results of TOF-SIMS measurement. From these results, we concluded that the complex particles such as the iron particles emitted from a railroad combined with diesel exhaust particles (DEPs) were suspended in the urban air environment.

TOF-SIMS measurement for the complex particulate matter in urban air environment

We developed the measurement method for the complex particulate matter in urban air environment using micro-beam analyses [electron probe microanalysis (EPMA), field emission type scanning electron microscope (FE-SEM), and TOF-SIMS]. In this study, the environmental particles collected at the location near both the traffic route and the railroad were characterized. By the EPMA analysis and FE-SEM observation, it became clear that many iron particles adsorbed smaller environmental particles on surface. The most of adsorbed particles were the carbonaceous particles containing small amount of silicon, as observed from the results of TOF-SIMS measurement. From these results, we concluded that the complex particles such as the iron particles emitted from a railroad combined with diesel exhaust particles (DEPs) were suspended in the urban air environment.

Microstructure and texture through thickness of ultralow carbon IF steel sheet severely deformed by accumulative roll-bonding

Ultralow carbon interstitial free (IF) steel was severely deformed up to a strain of 5.6 by the Accumulative Roll-bonding (ARB) process at 773 K. Crystallographic analysis by electron back-scattering diffraction (EBSD) technique in a field-emission type scanning electron microscope (FE-SEM) was carried out for the ARB processed IF steel throughout thickness of the sheet. Microstructural parameters, such as grain size, grain boundary misorientation and crystal orientation, through thickness of the ARB processed specimen were quantitatively clarified by the EBSD analysis. The ARB processed material was homogeneously filled with the lamellar or pancake-shaped ultrafine grains whose mean grain thickness were about 200–300 nm. More than 80% of the boundaries surrounding the ultrafine grains were high-angle grain boundaries. The ARB processed sheet had unique and complex textural distribution through thickness. The region near the thickness center has the conventional but quite weak rolling texture mainly composed of 〈110〉//RD and 〈111〉//ND. On the other hand, the surface region had the sharp shear texture, ND//〈110〉. Such a textural distribution is due to the redundant shear strain induced by high-friction between the sheet and roll during rolling. The correspondence between the textural and microstructural distribution and the shear strain distribution throughout thickness of the sheet was discussed.

化学機械研磨（ＣＭＰ）処理を利用した中炭素鋼焼もどしマルテンサイトの微細組織観察法の開発

A new observation method was developed for visualizing microstructure on a chemical-mechanically polished (CMP) surface for tempered martensite of a medium-carbon steel (JIS-SCM440).The CMP and an electropolished (EP) surfaces were observed using an atomic force microscope (AFM) and a field emission type-scanning electron microscope (FE-SEM), respectively. AFM images, FE-secondary and backscattering electron images and electron backscattering patterns (EBSP) were obtained for the CMP and EP surfaces.The AFM and FE-secondary electron images of the EP surface clearly visualized blocks and cementite particles, since the unevenness corresponding to blocks and cementite particles were formed by the electropolishing.On the other hand, the AFM image of the CMP surface revealed that the CMP process produced a very smooth surface with unevenness not exceeding 10 nm. The FE-backscattering electron images of the CMP surface only visualized the crystal-misorientation of the martensite matrix microstructure clearly, since the images are not influenced by the surface unevenness.The CMP surface is more appropriate than the EP surface for the EBSP measurement, since the unevenness of the CMP surface is smoother than that of the EP surface. Blocks with high-angle boundary beyond 15° could be recognized by EBSP mapping, but laths with low-angle boundary bellow 3° could not be done.

Influence of Work Condition and Microstructure on the Directionally Deformed Surface by Shot Peening

High durability is required for automotive engine valve springs. To ensure the performance of spring, it is necessary to evaluate and measure the residual stress distribution of spring surface and inward direction. Generally, it has been assumed that the residual stress of a material surface treated by the shot peening is uniform. However, the round and spiral shape of a coil spring brings various peening angles corresponding to the surface location, then the uneven peening angles may leads to a non-uniform residual stress on the coil spring surface. In the meanwhile, an analysis method of non-liner sin2 φ diagram, or φ-split analysis, is well known to directionally deformed material. In this study, residual stress distribution of spring material deformed by the shot peening from the different angles was measured and, non-linearity of sin2 φ diagram was studied. In addition, the relationship between microstructure and residual stress was studied by using field emission type scanning electron microscope (FE-SEM). The result reveals that the non-linearity in the sin2 φ diagram for the shot peening samples. The extent of φ-split became larger with the increasing shot peening angle and was dependent not only on the mass fraction of carbide particles but also on the carbide particles size distribution.

Nanoscale crystallographic analysis of ultrafine grained IF steel fabricated by ARB process

Nanoscale crystallographic features of ultrafine grained interstitial free steel fabricated by accumulative roll-bonding (ARB) process have been studied by electron back-scattered diffraction in field-emission type scanning electron microscope. This work has clearly indicated that most of the elongated ultrafine grains in the ARB processed sheet are surrounded by high-angle grain boundaries. The characteristic textures in the ARB processed sheet were also clarified.

Microstructure of AgI–Ag 2O–B 2O 3 fast ion conducting glasses with large amounts of AgI

The microstructure of twin-roller quenched glasses in the system AgI–Ag 2O–B 2O 3 (Ag 2O/B 2O 3=3) has been investigated by means of a field emission type scanning electron microscope (FE-SEM). Fine particles, 40–60 nm in diameter, were dispersed in twin-roller quenched glasses with 75 mol% AgI, for which no X-ray diffraction peaks due to crystalline phases were observed. The particle size observed in the glass with 75 mol% AgI was larger than that of the α-AgI particles 20–30 nm in diameter) observed in the α-AgI-stabilized composite with 82 mol% AgI. The larger particles observed in the glass with 75 mol% AgI were probably an AgI rich amorphous phase. The AgI rich amorphous particles aggregated to form island regions, several hundreds of nanometers in size when the AgI content was increased from 75 to 80 mol%. Such island regions were shown to be composed of finely dispersed α-AgI particles of 20–30 nm in diameter and an amorphous part. Similar island regions were also observed when the glass with 75 mol% AgI was heat-treated up to 120 ∘C. In both cases α-AgI nuclei present in the AgI rich amorphous phase grow to form α-AgI microcrystals in the quenching process of a melt containing 80–82 mol% AgI or in the reheating process on a glass with 75 mol% AgI.

Ultrastructural alterations of the myocardium induced by doxorubicin. A scanning electron microscopic study.

Morphologic changes in Doxorubicin (DXR)-induced cardiomyopathy are characterized by marked dilatation of the sarcoplasmic reticulum (SR). DXR was administered to New Zealand White rabbits for 5 or 8 weeks and the three-dimensional structure of the sarcotubular system in cardiac muscle cells from each rabbit was examined under a field-emission type scanning electron microscope (SEM) after removal of cytoplasmic matrices by the osmium-DMSO-osmium procedure. Five weeks after the initial injection of DXR, partial dilatation of the SR and damaged mitochondria with lysis of cristae were observed three-dimensionally. After 8 weeks, the three-dimensional structure of the SR showed extensive spherical ballooning which could be seen clearly in bold relief. Thus, we could directly visualize structural alterations of the sarcotubular system in DXR-induced cardiomyopathy using the SEM.

Scanning electron-microscopic studies on the three-dimensional structure of sarcoplasmic reticulum in the mammalian red, white and intermediate muscle fibers.

The three-dimensional structure of the sarcoplasmic reticulum (SR) in the red, white and intermediate striated muscle fibers of the extensor digitorum longus muscle of the rat was examined under a field-emission type scanning electron microscope after removal of cytoplasmic matrices by the osmium-DMSO-osmium procedure. In all three types of fibers, the terminal cisternae and transverse tubules form triads at the level of the A-I junction. Numerous slender sarcotubules, originating from the A-band side terminal cisternae, extend obliquely or longitudinally and form oval or irregular shaped networks of various sizes in front of the A-band, then become continuous with the tiny mesh (fenestrated collar) in front of the H-band. The A- and H-band SR appears as a single sheet of anastomotic tubules. Numerous sarcotubules, originating from the I-band side terminal cisternae, extend in three-dimensional directions and form a multilayered network over the I-band and Z-line regions. At the I-band level, paired transversely oriented mitochondria partly embrace the myofibril. The I-band SR network is poorly developed in the narrow space between the paired mitochondria, but is well developed in places devoid of these mitochondria. The three-dimensional structure of the SR is basically the same in all three muscle fiber-types. However, the SR is sparse on the surface of mitochondria, so the mitochondria-rich red fiber has a much smaller total volume of SR than the mitochondria-poor white fiber. Moreover, the volume of SR of the intermediate fiber is intermediate between the two.