Silicon lattice comparisons related to the Avogadro project: uniformity of new material and surface preparation effects

Thinning out MoS2 crystals to atomically thin layers results in the transition from an indirect to a direct bandgap material. This makes single layer MoS2 an exciting new material for electronic devices. In MoS2 devices it has been observed that the choice of materials, in particular for contact and gate, is crucial for their performance. This makes it very important to study the interaction between ultrathin MoS2 layers and materials employed in electronic devices in order to optimize their performance. In this work we used NC-AFM in combination with quantitative KPFM to study the influence of the substrate material and the processing on single layer MoS2 during device fabrication. We find a strong influence of contaminations caused by the processing on the surface potential of MoS2. It is shown that the charge transfer from the substrate is able to change the work function of MoS2 by about 40 meV. Our findings suggest two things. First, the necessity to properly clean devices after processing as contaminations have a great impact on the surface potential. Second, that by choosing appropriate materials the work function can be modified to reduce contact resistance.

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Influence of Surface Preparation on Cracking Phenomena in TIG-Welded High and Medium Entropy Alloys

Journal of Manufacturing and Materials Processing ◽

10.3390/jmmp6010005 ◽

2021 ◽

Vol 6 (1) ◽

pp. 5

Author(s):

Tim Richter ◽

Marcel Giese ◽

Michael Rhode ◽

Dirk Schroepfer ◽

Thomas Michael ◽

...

Keyword(s):

Surface Preparation ◽

High Strength ◽

Fusion Welding ◽

High Entropy Alloy ◽

High Entropy ◽

Fracture Topography ◽

Electron Microscopy Analysis ◽

Materials Research ◽

New Material ◽

Film Separation

Multi-element systems with defined entropy (HEA—high entropy alloy or MEA—medium entropy alloy) are rather new material concepts that are becoming increasingly important in materials research and development. Some HEA systems show significantly improved properties or combinations of properties, e.g., the overcoming of the trade-off between high strength and ductility. Thus, the synthesis, the resulting microstructures, and properties of HEA have been primarily investigated so far. In addition, processing is crucial to achieve a transfer of potential HEA/MEA materials to real applications, e.g., highly stressed components. Since fusion welding is the most important joining process for metals, it is of vital importance to investigate the weldability of these materials. However, this has rarely been the subject of research to date. For that reason, in this work, the weldability depending on the surface preparation of a CoCrFeMnNi HEA and a CoCrNi MEA for TIG welding is investigated. The fusion welding of longer plates is described here for the first time for the CoCrNi alloy. The welds of both materials showed distinct formation of cracks in the heat affected zone (HAZ). Optical and scanning electron microscopy analysis clearly confirmed an intergranular fracture topography. However, based on the results, the crack mechanism cannot be conclusively identified as either a liquid metal embrittlement (LME) or hot cracking-like liquid film separation.

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Влияние наличия достаточно высокой концентрации фосфора на концентрационное распределение галлия в кремнии

Физика и техника полупроводников ◽

10.21883/ftp.2022.02.51962.9666 ◽

2022 ◽

Vol 56 (2) ◽

pp. 199

Author(s):

М.К. Бахадирханов ◽

Н.Ф. Зикриллаев ◽

С.Б. Исамов ◽

Х.С. Турекеев ◽

С.А. Валиев

Keyword(s):

High Concentration ◽

Silicon Lattice ◽

Unit Cells ◽

New Material ◽

Significant Change ◽

Electrophysical Parameters

It was found that the silicon preliminarily doped with a high concentration of phosphorus during the diffusion of gallium, there is a significant increase in the solubility of the gallium. The results obtained are explained by the interaction of gallium and phosphorus atoms, as a result of which quasi-neutral molecules [P+Ga-] are formed. It is assumed that the formation of such quasineutral molecules [P+Ga–] stimulates the formation of Si2GaP binary unit cells in the silicon lattice. It is shown that a sufficiently high concentration of such unit cells can lead to a significant change in the electrophysical parameters of silicon, i.e. the possibility of obtaining a new material based on silicon.

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EELS characterization of “Smut” layer films on steel surface prepared for chrome plating by anodic etching

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100139068 ◽

1995 ◽

Vol 53 ◽

pp. 538-539

Author(s):

E Y. Wang ◽

J. T. Cherian ◽

A. Madsen ◽

R. M. Fisher

Keyword(s):

Steel Surface ◽

Surface Preparation ◽

Treatment Method ◽

Chrome Plating ◽

Transmission Electron ◽

Alloy Steels ◽

Pre Treatment ◽

Hard Chrome ◽

Electron Energy Loss

Many steel parts are electro-plated with chromium to protect them against corrosion and to improve their wear-resistance. Good adhesion of the chrome plate to the steel surface, which is essential for long term durability of the part, is extremely dependent on surface preparation prior to plating. Recently, McDonnell Douglas developed a new pre-treatment method for chrome plating in which the steel is anodically etched in a sulfuric acid and hydrofluoric acid solution. On carbon steel surfaces, this anodic pre-treatment produces a dark, loosely adhering material that is commonly called the “smut” layer. On stainless steels and nickel alloys, the surface is only darkened by the anodic pre-treatment and little residue is produced. Anodic pre-treatment prior to hard chrome plating results in much better adherence to both carbon and alloy steels.We have characterized the anodic pre-treated steel surface and the resulting “smut” layer using various techniques including electron spectroscopy for chemical analysis (ESCA) on bulk samples and transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) on stripped films.

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Selective Corrosion of brazed joint between BNi-2 filler metal and stainless steel 316

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100163551 ◽

1996 ◽

Vol 54 ◽

pp. 218-219

Author(s):

H. S. Kim ◽

R. U. Lee

Keyword(s):

Stainless Steel ◽

Filler Metal ◽

Surface Preparation ◽

Optical Microscope ◽

Heating Element ◽

Incomplete Fusion ◽

Atmospheric Conditions ◽

Leak Test ◽

High Temperature Side ◽

Inconel 600

A heating element/electrical conduit assembly used in the Orbiter Maneuvering System failed a leak test during a routine refurbishment inspection. The conduit, approximately 100 mm in length and 12 mm in diameter, was fabricated from two tubes and braze-joined with a sleeve. The tube on the high temperature side (heating element side) and the sleeve were made of Inconel 600 and the other tube was stainless steel (SS) 316. For the filler metal, a Ni-Cr-B brazing alloy per AWS BNi-2, was used. A Helium leak test spotted the leak located at the joint between the sleeve and SS 316 tubing. This joint was dissected, mounted in a plastic mold, polished, and examined with an optical microscope. Debonding of the brazed surfaces was noticed, more pronounced toward the sleeve end which was exposed to uncontrolled atmospheric conditions intermittently. Initially, lack of wetting was suspected, presumably caused by inadequate surface preparation or incomplete fusion of the filler metal. However, this postulation was later discarded based upon the following observations: (1) The angle of wetting between the fillet and tube was small, an indication of adequate wetting, (2) the fillet did not exhibit a globular microstructure which would be an indication of insufficient melting of the filler metal, and (3) debonding was intermittent toward the midsection of the sleeve.

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Characterization of a monolayer graphitic structure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171535 ◽

1994 ◽

Vol 52 ◽

pp. 760-761

Author(s):

X. Lin ◽

X. K. Wang ◽

V. P. Dravid ◽

J. B. Ketterson ◽

R. P. H. Chang

Keyword(s):

Three Dimensional ◽

Single Layer ◽

Synthesis Process ◽

Graphitic Structure ◽

Positive Gaussian Curvature ◽

Graphitic Sheet ◽

Structural And Electronic Properties ◽

New Material ◽

Hexagonal Network

For small curvatures of a graphitic sheet, carbon atoms can maintain their preferred sp2 bonding while allowing the sheet to have various three-dimensional geometries, which may have exotic structural and electronic properties. In addition the fivefold rings will lead to a positive Gaussian curvature in the hexagonal network, and the sevenfold rings cause a negative one. By combining these sevenfold and fivefold rings with sixfold rings, it is possible to construct complicated carbon sp2 networks. Because it is much easier to introduce pentagons and heptagons into the single-layer hexagonal network than into the multilayer network, the complicated morphologies would be more common in the single-layer graphite structures. In this contribution, we report the observation and characterization of a new material of monolayer graphitic structure by electron diffraction, HREM, EELS.The synthesis process used in this study is reported early. We utilized a composite anode of graphite and copper for arc evaporation in helium.

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Cross-sectional TEM specimen preparation from magneto-optical disk by ultramicrotomy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100147028 ◽

1993 ◽

Vol 51 ◽

pp. 236-237

Author(s):

F. Shaapur ◽

M.J. Kim ◽

Seh Kwang Lee ◽

Soon Gwang Kim

Keyword(s):

System Development ◽

Thin Foil ◽

Specimen Preparation ◽

Material System ◽

Cross Sectional ◽

Protective Layers ◽

New Material ◽

Diamond Saw ◽

Original Production ◽

Thick Medium

TEM characterization and microanalysis of the recording media is crucial and complementary to new material system development as well as quality control applications. Due to the type of material generally used for supporting the medium, i.e., a polymer, conventional macro- and microthinning procedures for thin foil preparation are not applicable. Ultramicrotorny (UM) is a viable option and has been employed in previous similar studies. In this work UM has been used for preparation of XTEM samples from a magneto-optical (MO) recording medium in its original production format.The as-received material system consisted of a 4-layer, 2100 Å thick medium including a 300 Å TbFeCo layer enveloped by silicon nitride protective layers supported on a 1.2 mm thick × 135 mm (5.25 in.) diameter polycarbonate disk. Recording tracks had an approximate pitch of 1.6 μm separated by 800 Å deep peripheral grooves. Using a Buehler Isomet low-speed diamond saw, 1 mm wide and 20 mm long strips were cut out of the disk along the recording tracks.

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The Case of Thematic Tests Adapted to Older Adults

Rorschachiana Journal of the International Society for the Rorschach ◽

10.1027/1192-5604/a000015 ◽

2011 ◽

Vol 32 (1) ◽

pp. 46-71 ◽

Cited By ~ 6

Author(s):

Benoît Verdon

Keyword(s):

Older Adults ◽

Older Persons ◽

Older Men ◽

Elderly Persons ◽

Mental Processes ◽

Men And Women ◽

Projective Tests ◽

New Material ◽

Older Men And Women ◽

Latent Content

Since the 1950s, the growing interest of clinicians in using projective tests to study normal or pathological aging processes has led to the creation of several thematic tests for older adults. This development reflects their authors’ belief that the TAT is not suitable to the concerns and anxieties of elderly persons. The new material thus refers explicitly to situations related to age; it aims to enable older persons to express needs they cannot verbalize during consultations. The psychodynamic approach to thematic testing is based on the differentiation between the pictures’ manifest and latent content, eliciting responses linked to mental processes and issues the respondent is unaware of. The cards do not necessarily have to show aging characters to elicit identification: The situations shown in the pictures are linked to loss, rivalry, helplessness, and renunciation, all issues elderly respondents can identify with and that lead them to express their mental fragilities and resources. The article first explains the principles underlying four of these thematic tests, then develops several examples of stories told for card 3BM of the TAT, thus showing the effectiveness of this tool for the understanding and differentiation of loss-related issues facing older men and women.

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Increase of resistance of piercing mill mandrels at seamless pipes production of 13Cr grade martensite class stainless steel at line ТПА 159‒426 of JSC VTZ

Ferrous Metallurgy Bulletin of Scientific Technical and Economic Information ◽

10.32339/0135-5910-2020-12-1259-1264 ◽

2020 ◽

Vol 76 (12) ◽

pp. 1259-1264

Author(s):

I. I. Lube ◽

N. V. Trutnev ◽

S. V. Tumashev ◽

A. V. Krasikov ◽

A. G. Ul’yanov ◽

...

Keyword(s):

Chemical Composition ◽

Oil And Gas ◽

Cobalt Content ◽

Pipe Plant ◽

Piercing Mill ◽

Steel Strength ◽

New Material ◽

Chemical Composition Of Steel ◽

Technical Solutions ◽

Grade Steel

At production of pipes of type 13Cr grade steel used at development of oil and gas deposits in areas with aggressive environment, intensive wear of instrument takes place, first of all, piercing mill mandrels. Factors, influencing the resistivity of the piercing mandrels considered, including chemical composition of the material, the mandrel is made of and its design. Based on industrial experience it was shown, that chrome content in the mandrel material practically does not affect on the increase of its resistivity, since the formed thin protective oxides having high melting temperature, are quickly failed and practically are not restored in the process of piercing. To increase the resistivity of piercing mandrels at production of casing tubes of type 13Cr grade steel, a work was accomplished to select a new material for their manufacturing. The chemical composition of steel presented, which was traditionally used for piercing mandrels manufacturing, as well as a steel grade proposed to increase their resistivity. First, molybdenum content was increased, which increases the characteristics of steel strength and ductility at high temperatures and results in grain refining. Second, tungsten content was also increased, which forms carbides in the steel resulting in an increase of its hardness and “red resistivity”, as well as in preventing grains growth during heating. Third, cobalt content was also increased, which increases heat resistivity and shock loads resistivity. The three elements increase enabled to increase the mandrels resistivity by two times. Results of mandrel test of steel 20ХН2МВ3КБ presented, the mandrel having corrugation on the working cone surface, which enabled to reach the resistivity growth to 12 passes without significant change of instrument cost. Microstructure of mandrels made of steels 20Х2Н4МФА and 20ХН2МВ3КБ shown. Application of the centering pin of special design was tested, which provided forming of a rounding edge on the front billet ends, eliminated undercut of mandrel external surface in the process of secondary billet grip and increase the service life of the piercing mill mandrels. At production of seamless pipes of martensite class type 13Cr stainless steels having L80 group of strength, an increase of piercing mandrel resistivity was reached by more than four times, which together with other technical solutions enabled to increase the hourly productivity of the hot rolling section of Volzhsky pipe plant ТПА 159-426 line by more than two times.

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