Raster Electron Microscopy Research Articles

Focused Ion Beam Methods for Research and Control of HEMT Fabrication

The combination of ion-beam spraying and raster electronic microscopy allows to receive images of sections of defects of the growth nature origin in epitaxial films on GaN basis with nanodimensional permission, to carry out their analysis and classification irrespective of conditions of receiving. Results of application of the specified methods for the analysis of technological operations when forming the microwave transistors are considered: formations of locks, receiving of holes and drawing of contacts.

The Structure Formation of the Cellular Concrete with Nanostructured Modifier

In this work the peculiarities of phase formation of the cement stone at presence of nanostructured modifier of the silica composition were identified using the method of x-ray diffraction and raster electronic microscopy. Also the character of influence of modifier on the structure formation of the cement stone was defined. Polydisperse modifier with the presence of a highly active colloidal component, on the one hand, acts as a pozzolanic component, and on the other hand – as a submicron filler.

Investigation of textured aluminum nitride films prepared by chemical vapor deposition

Textured polycrystalline aluminum nitride films are grown on a silica substrate by chemical vapor deposition using metallic aluminum and ammonium chloride as the initial reagents. The good texture and crystal quality of the prepared films are confirmed by raster electron microscopy, Raman spectroscopy, and X-ray diffraction.

The development of a purification technique of metallurgical silicon to silicon of the solar brand

The experimental results that show the possibility of obtaining silicon of the solar brand by the recrystallization of metallurgical silicon in fusible metals, e.g., tin, and growing monocrystalline silicon ingots from the obtained silicon scales by the Czochralski method are presented. The experiments on purifying fusible metal (tin) after ending a cycle to obtain silicon scales for the purpose of its repeated use were made. Tin purification was carried out by the method of vacuum decontamination of tin melt, its filtration, and then zone recrystallization. The qualitative and quantitative analysis of the initial materials (silicon and tin) and their structure after various stages of the technological process was carried out by the method of the roentgen-fluorescent analysis on the Elvax light device. The structural features of the obtained silicon scales were considered by means of raster electronic microscopy on the REMMA106I device. The conductivity type and the specific electric resistance of the obtained silicon monocrystalline ingot were measured by the fourprobe method on the PIUS-1UM-K device. It was shown that the grown monocrystalline silicon ingot has silicon content of at least 99.999% weight, n-type conductivity, and specific electric resistance of at least 2.0 Оhm сm. The described parameters correspond to the silicon the solar brand and confirm the possibility of obtaining it from metallurgical silicon by recrystallization in fusible metals, for example, tin.

Granulated catalytic materials based on chitosan and its derivatives

The method of fabrication of palladium-containing materials based on molded granules of chitosan and its imidazolyl and pyridyl derivatives crosslinked with glutaric aldehyde has been suggested. It has been established by example of the reaction of reduction of p-nitrophenol by sodium boron hydride that the reaction rate increases along with the decrease in the degree of swelling of catalyst support granules. It has been demonstrated using the methods of X-ray photoelectron spectroscopy, raster electron microscopy, and energy-dispersive X-ray spectroscopy that in granules palladium is concentrated in the surface layer with a thickness of 8–10 μm, whereas the profile of the palladium distribution in strongly swelling granules is diffused, and its subsurface content is lower, which results, aside from a dramatic granule collapse, in the decrease in the catalytic activity of such Pd0-containing materials.

Spatiotemporal dynamics of the pollution of Al–Fe-humus podzols in the impact zone of a nonferrous metallurgical plant

The dependence of the level of contamination of the upper horizon of Al–Fe-humus podzols (Podzols Rustic) with heavy metals (Ni, Cu) on the distance from the Severonickel smelter (Monchegorsk, Murmansk oblast) was studied on a number of test plots in the medium-aged pine stands. It was found that metal concentrations in the soils could be reasonably approximated by the negative exponential function. In the buffer zone of the smelter, the concentrations of Ni and Cu exceed background values by 8–17 times; in the impact zone, by 50–100 times. The study of the dynamics of acid-soluble forms of Ni and Cu in the organic horizons of podzols on the key plots showed that the boundaries of polluted territory shift towards background regions despite the recent five–eightfold decrease in the emissions. The concentrations of heavy metals in the litter horizons continued to increase in the buffer zone. In the impact zone, their contamination remained at the very high level. Firm bounding of heavy metals in the organic horizon coupled with their continuing aerial input did not allow the beginning of the soil self-purification process, which might last for decades and centuries. Raster electron microscope and X-ray spectral microanalysis showed that particles (>85%) of the ashed matter of organic horizons from the background region, the buffer zone, and the impact zone is mainly represented by various soil-forming minerals and iron oxides (in particular, magnetite). In the samples from the impact zone, about 5% of the mineral particles had the surface morphology and chemical composition typical of dust particles emitted into the air by metal smelters. Most probably, these spherical particles represented magnetite Fe3O4 enriched in heavy metals (Cu, Ni).

Study of Products of Metallic Titanium Electrospark Dispersion in Aqueous Medium

The results of electrospark dispersion of the metallic titanium loading in aqueous medium are presented in the paper. Raster electronic microscopy, X-ray phase analysis and BET method were used to investigate properties of the obtained powder. Values of specific surface are given in the paper, and morphology and structure of the obtained powders are studied. It is established that chemical and phase composition of the obtained powders is identified by properties of the molten titanium to interact with the dissolved in dispersion medium gaseous products.

A Mössbauer study of iron and iron–cobalt nanotubes in polymer ion-track membranes

Iron and iron–cobalt nanostructures that were synthesized in polymer ion-track membranes have been studied via Mossbauer spectroscopy combined with raster electron microscopy, energy-dispersion analysis, and X-ray diffraction data. The obtained nanostructures are single-phase bcc Fe1–x Co x nanotubes with a high degree of polycrystallinity, whose length is 12 μm; their diameter is 110 ± 3 nm and the wall thickness is 21 ± 2 nm. Fe2+ and Fe3+ cations were detected in the nanotubes, which belong to iron salts that were used and formed in the electrochemical deposition. The Fe nanotubes exhibit eventual magnetic moment direction distributions of Fe atoms, whereas Fe/Co nanotubes have a partial magnetic structure along the nanotube axis with a mean value of the angle between the magnetic moment and nanotube axis of 34° ± 2°. Substituting the Fe atom with Co in the nearest environment of the Fe atom within the Fe/Co structure of nanotubes leads to a noticeable increase in the hyperfine magnetic field at the 57Fe nuclei (by 8.7 ± 0.4 kOe) and to a slight decrease in the shift of the Mossbauer line (by 0.005 ± 0.004 mm/s).

Analysis of Corrosion Defects on Oil Pipeline Surface Using Scanning Electron Microscopy and Soil Thionic and Sulfate-reducing Bacteria Quantification

We completed an analysis of corrosion defects on oil pipeline surface by instrumentality of scanning electron microscopy and identified soil thionic and sulfate-reducing bacteria quantity. A surface of samples was studied by using of raster electron microscopy as a preparation for qualitative and quantitative analysis of elemental composition. Was identified a quantity of sulfate-reducing and thionic bacteria in a samples of soil contiguous to the surface of underground oil pipelines in the of Khanty- Mansiysk autonomous region territory (Ugra). A result of this research shows a significant oxidative activity, which accompanied an expressed corrosion process. Microbiological analysis of soil shows an existence of thionic bacteria and an absence of sulfate- reducing bacteria. Microorganisms existed in soil induces the corrosion of pipeline steel. Using of scanning electron microscopy in a combination with finding of quantitative specification of thionic and sulfate-reducing bacteria in soils allows to study the nature of corrosive surface of the oil pipelines and to evaluate an extension degree of biocorrosion in complex.

Stimulated emission from aluminium anode oxide films doped with rhodamine 6G

The spectral and luminescent properties of the rhodamine 6G dye in a porous matrix of aluminium anode oxide are studied. The films with a highly-ordered porous structure are produced using the method of two-stage anodic oxidation. By means of raster electron microscopy it is found that the diameter of the pores amounts to nearly and the separation between the adjacent channels is almost . The thickness of the films is equal to , and the specific surface area measured using the method of nitrogen capillary condensation is . Fluorescence and absorption spectra of rhodamine 6G molecules injected into the pores of the aluminium anode oxide are measured. It is found that under the excitation of samples with the surface dye concentration by the second harmonic of the Nd : YAG laser in the longitudinal scheme with the pumping intensity , a narrow band of stimulated emission with the intensity maximum at the wavelength appears against the background of the laser-induced fluorescence spectrum. A further increase in the pumping radiation intensity leads to the narrowing of the stimulated emission band and an increase in its intensity. The obtained results demonstrate the potential possibility of using the porous films of aluminium anode oxide, doped with laser dyes, in developing active elements for quantum electronics.

Особенности формирования стереоскопических изображений растровым электронным микроскопом

Особенности формирования стереоскопических изображений растровым электронным микроскопом

Application of raman spectroscopy method to the diagnostics of caries development

The object of study were human teeth with caries cavities and healthy teeth extracted for orthopaedic indications. The main method of study was Raman spectroscopy. We revealed the specific features of Raman spectra for the healthy tooth tissues impaired ones and the tissues affected by caries. The optical criteria are established that allow cares detection and assessment, as well as the detection of pre-caries impairment of the tooth tissues. The results were analysed in comparison with the data of the chemical analysis performed using a raster electron microscope.

Spectral interference in a carbide-silicon n −-n + structure

The spectral interference in carbide-silicon structure in which the epitaxial layer and substrate differ only by the imaginary part of the refractive index is demonstrated. The thickness of the layer that is determined from the period of interference is verified using the direct measurements of the layer thickness with the aid of raster electron microscopy. The spectral dependence of the real part of refractive index of silicon carbide is extended to wavelength interval 1.5–7 μm.

3D reconstruction for a scanning electron microscope

An algorithm for the reconstruction of the 3D shape of the surface of a micro-object from a stereo pair of images obtained on a raster electron microscope (REM) has been considered. A model of building an image in REM has been presented. The SIFT algorithm was used for determination of the correspondence points. The correspondence points are used to determine the mutual position of the object in a stereo pair by the RANSAC method. A set of points is created in the 3D space, which is later interpolated to reconstruct the 3D surface.

Структура и фазовый состав нового керамического материла, получаемого из продукта химического диспергирования сплава АМг12

Results of raster electronic microscopy of structure and the X-ray phase analysis of a developed alyumooksidny material at various stages of technological process of its production are presented: dry deposit - a product of chemical dispergating of an aluminum-magnesium alloy of AMG 12, a deposit after heat treatment on air (1400 °C, 1 hour) and baked on air (1500 °C, 1 hour).<br />

Laboratory evaluation of toothbrush/toothpaste abrasion resistance after smooth enamel surface sealing

The use of dental sealants has been extended to smooth enamel surfaces. The present study was conducted to test the in vitro performance of four sealants with different characteristics (highly and lowly filled, self-etching features). Eighty human teeth (lower incisors and premolars) were randomly divided into following sealant test groups: ProSeal(TM), LightBond(TM), OrthoSolo(TM), and Seal&Protect(®). Twenty untreated teeth served as a control group. Tooth brushing was conducted for a period of time simulating 12, 18, and 24 months. During the toothbrush abrasion protocol, the specimens were subjected to thermal and acidic challenge. Sealant thickness was determined with μCT imaging, and qualitative and quantitative surface effects were investigated using stereo microscopy and raster electron microscopy, respectively. Data were subjected to t test or Kruskal-Wallis/Mann-Whitney tests (alpha, 5%). The wear behavior and film integrity of highly filled sealants were superior to lowly filled sealants. Even after 1 year of tooth brushing, significant surface deterioration with deleterious loss of enamel and discoloration was observed in all tested materials (χ(2) = 15.349; P = 0.004). The size of the observed defects increased over time. These results suggest that the application of sealants on smooth enamel surfaces should be limited to special indications, and their usefulness has to be revisited. Based on the results of this in vitro study, the general overall application of enamel sealants needs to be questioned.

Structure and phase composition of a chromium-silicon system modified by high-current electron beams

The results of studies of the structure-phase state of a chromium-coated silicon substrate system’s subsurface layer treated with low-energy high-current electron beams, 50–200 μs in duration and with an energy density of 15 J/cm2, are reported. The data of raster electron microscopy and X-ray structural and spectral microanalysis revealed the formation of a chromium-doped silicon layer with a thickness of 2–38 μm, chromium-enriched silicon dendrites, chromium disilicide CrSi2, and an amorphous eutectic layer (the characteristic cross-section size of the chromium-enriched phase extrusions is ∼50 nm). The structure-phase transformations are discussed taking into account the peculiarities of the distribution of temperature, diffusion and convective mass-transfer in the modified layer.

STRUCTURE AND PROPERTIES OF NANOCRYSTALLINE COATINGS TITANIUM NITRIDE COATING DEPOSITION RECEIVED AT ARC DISCHARGE WITH HF AND STIMULATION

With the raster electron microscope (SEM), XRD defraction, adgesion strength, friction coefficient and wear rate of material properties of the coatings were studied nc — TiN. Depending on the bias potential applied to the substrate and the chamber pressure, the inclusion of high-frequency discharge, it is shown that the combination of different parameters recorded during scratching, allows to distinguish between the critical load thresholds that are linked to different typesof cohesive and adhesive fracture coatings in tribological tests. Nanograin sizes were determined nc — TiN coating stoichiometry and phase of elemental composition and surface morphology of the coatings.

Vacuum electron beam deposition of carbide steels: Part 3. Effect of the number of passes on the structure and phase condition of composite coatings based on R6M5 high-speed steel

Influence of the number of an electron beam runs on the structural phase state of the hardened case on the base of steel P6M5 and steel P6M5+20% WC compound is studied by the methods of optical and raster electronic microscopy, roentgen fluorescent analysis. It is shown that two morphological carbide types are distinguished in the tree-run weld deposition, i.e. elongated along the austenitic granule lines and small equiaxed in volume granules. This gives significant increase in microhardness of the hardened case.

New challenges for tafoni research. A new approach to understand processes and weathering rates

AbstractCavernous tafoni‐type weathering is a common and conspicuous global feature, creating artistic sculptures, which may be relevant for geochemical budgets. Weathering processes and rates are still a matter of discussion. Field evidence in the type locality Corsica revealed no trend of size variability from the coast to subalpine elevations and the aspect of tafoni seems to be governed primarily by the directions of local fault systems and cleavage, and only subordinately by wind directions or the aspect of insulation. REM analysis of fresh tafone chips confirmed mechanical weathering by the crystallization of salts, as conchoidal fracturing of quartz is observed. The salts are only subordinately provided by sea spray, as calcium and sodium sulfates rather than halite dominate even close to the coast. Characteristic element ratios compare well with aerosols from mixed African and European air masses. Sulfates are largely derived from Sahara dust, indicated by their sulfur isotopic composition. Salt crystals form by capillary rise within the rock and subsequent crystallization in micro‐cracks and at grain boundaries inside rain‐protected overhangs. Siderophile bacteria identified by raster electron microscopy (REM) analysis of tafone debris contribute to accelerated weathering of biotite and tiny sulfide ore minerals. By applying 10Be‐exposure dating, weathering rates of large mature tafone structures were found to be about an order of magnitude higher than those on the exposed top of the affected granite blocks. Copyright © 2010 John Wiley &amp; Sons, Ltd.