scholarly journals Study of Helium Swelling in Nitride Ceramics at Different Irradiation Temperatures

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2415 ◽  
Author(s):  
Maxim. V. Zdorovets ◽  
Kanat Dukenbayev ◽  
Artem. L. Kozlovskiy
Keyword(s):  
Crystal Structure ◽  
Surface Layer ◽  
Room Temperature ◽  
Sharp Decrease ◽  
Radiation Doses ◽  
Near Surface ◽  
Helium Bubbles ◽  
Density Of Dislocations ◽  
Nitride Ceramics ◽  
Average Size

This paper presents the results of a systematic study of helium swelling and the subsequent process of degradation of the near-surface layer of aluminum-based nitride ceramics. The samples were irradiated with 40 keV He2+ ions at temperatures of 300 and 1000 K with a fluence of 1 × 1017–5 × 1017 ions/cm2. The choice of radiation doses and temperature conditions was due to the possibility of simulating reactor tests of structural materials. It has been established that an increase in the irradiation fluence leads to the formation of large agglomerates of clusters of helium bubbles, as well as an increase in the degree of roughness and waviness of the surface with the formation of crater-like inclusions. In the case of irradiation at high temperatures, there was a slight decrease in the average size of helium inclusions compared with irradiation at room temperature. However, the density of inclusions and surface roughness were much higher. It is established that irradiation at room temperatures leads to a sharp decrease in ceramics density, as well as deformation of the crystal structure due to an increase in the density of dislocations and macrostresses in the structure. The decrease in ceramics density due to the formation of helium inclusions led to an increase in porosity and a defective fraction in the structure of the surface layer of ceramics.

scholarly journals Формирование преципитатов в Si, имплантированном ионами -=SUP=-64-=/SUP=-Zn-=SUP=-+-=/SUP=- и -=SUP=-16-=/SUP=-O-=SUP=-+-=/SUP=-

2018 ◽  
Vol 52 (8) ◽  
pp. 827
Author(s):  
В.В. Привезенцев ◽  
Е.П. Kириленко ◽  
А.В. Горячев ◽  
А.В. Лютцау
Keyword(s):  
Mass Spectrometry ◽  
Surface Layer ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Room Temperature ◽  
Secondary Ion Mass Spectrometry ◽  
Near Surface ◽  
Secondary Ion ◽  
Post Implantation ◽  
Scanning Electron

AbstractThe results of studying the surface Si layer and precipitate formation in CZ n -Si(100) samples sequentially implanted with ^64Zn^+ ions with a dose of 5 × 10^16 cm^2 and energy of 100 keV and ^16O^+ ions with the same dose but an energy of 33 keV at room temperature so that their projection paths R _ p = 70 nm would coincide are presented. The post-implantation samples are annealed for 1 h in an inert Ar medium in the temperature range of 400–900°C with a step of 100°C. The profiles of the implanted impurities are studied by time-of-flight secondary ion mass spectrometry. The Si surface is visualized using a scanning electron microscope, while the near-surface layer is visualized with the help of maps of elements formed by Auger electron spectroscopy with profiling over depth. The ZnO(002) texture is formed in an amorphized Si layer after the implantation of Zn and O ions. ZnO(102) crystallites of 5 nm in size are found in a recrystallized single-crystalline Si layer after annealing in Ar at 700°C.

scholarly journals Study of change in beryllium oxide strength properties as a result of irradiation with heavy ions

2021 ◽  
Vol 5 (3) ◽  
pp. 192-199
Author(s):  
M.V. Zdorovets ◽  
A.L. Kozlovskiy ◽  
D.B. Borgekov ◽  
D.I. Shlimas
Keyword(s):  
Heavy Ions ◽  
Mechanical Characteristics ◽  
Bending Strength ◽  
Sharp Decrease ◽  
Beryllium Oxide ◽  
Strength Properties ◽  
Strength Characteristics ◽  
Radiation Doses ◽  
Near Surface ◽  
Ion Energy

The paper presents data on changes in strength properties, including data on microhardness, crack resistance, bending strength and wear of BeO ceramics as a result of irradiation with heavy accelerated ions. The following types of ions were selected as heavy ions: O2+ (28 MeV), Ar8+ (70 MeV), Kr15+ (147 MeV), Xe22+ (230 MeV). Radiation doses were 1013 -1015 ion/cm2 , which make it possible to assess the effect of both single defects arising from radiation, and cluster overlapping defective areas occurring at large radiation doses. During the studies carried out, it was found that an increase in the ion energy and, consequently, in the damaging ability and depth of the damaged area, leads to a sharp decrease in the strength mechanical characteristics of ceramics, which is due to an increase in defective areas in the material of the near-surface damaged layer. However, an increase in irradiation dose for all types of exposure results in an almost equilibrium decrease in strength characteristics and the same trend of change in strength characteristics. The obtained dependencies indicate that the proposed mechanisms responsible for changing the strength properties can, under certain assumptions, be extrapolated to various types of exposure to heavy ions in the energy range (25-250 MeV).

scholarly journals Исследование морфологии поверхности и химического состава кремния, имплантированного ионами меди

2020 ◽  
Vol 90 (10) ◽  
pp. 1715
Author(s):  
В.В. Воробьев ◽  
А.И. Гумаров ◽  
Л.Р. Тагиров ◽  
А.М. Рогов ◽  
В.И. Нуждин ◽  
...  
Keyword(s):  
Surface Layer ◽  
Ion Beam ◽  
Single Crystal Silicon ◽  
Implantation Dose ◽  
Crystal Silicon ◽  
Copper Silicide ◽  
Near Surface ◽  
Si Substrates ◽  
Average Size ◽  
Cu Ions

This paper presents the results of studies of the structure and chemical composition of the surface of single-crystal silicon c-Si substrates implanted with Cu^+ ions with an energy of 40 keV and doses in the range of 3.1 · 10^15 - 1.25 · 10^17 ions/cm^2 at a current density in the ion beam of 8 μA/cm^2. Using scanning electron and probe microscopy in combination with X-ray photoelectron and Auger electron spectroscopy it was found that at the initial stage of irradiation with Cu^+ ions up to a dose of 6.25 · 10^16 ions/cm^2 Cu metal nanoparticles with an average size of 10 nm are formed in the surface layer of Si. With a further increase in the implantation dose starting from a value of 1.25 · 10^17 ions/cm^2 and higher the η-phase of copper silicide η-Cu3Si nucleates. This circumstance is due to the heating of the near-surface layer of Si substrate during its irradiation to a temperature conducive to the phase formation of η-Cu3Si.

scholarly journals DETERMINATION OF CRITICAL DOSES OF RADIATION DAMAGE TO ALN CERAMIC UNDER IRRADIATION OF HELIUM AND HYDROGEN IONS

2021 ◽  
Vol 18 (2) ◽  
pp. 23-28
Author(s):  
A.L. Kozlovskiy ◽  
Keyword(s):  
Thermal Conductivity ◽  
Surface Layer ◽  
Radiation Damage ◽  
Heat Conducting ◽  
Hydrogen Ions ◽  
Helium Ions ◽  
Subsequent Formation ◽  
Near Surface ◽  
Helium Bubbles

The work is devoted to the study of the radiation damage kinetics to heat-conducting, insulating and mechanical properties in polycrystalline ceramics based on aluminum nitride under irradiation of helium and hydrogen ions, as well as the determination of critical doses that cause maximum irreversible consequences. The choice of ions for irradiation is due to the ability to simulate the radiation damage processes during the accumulation of helium and hydrogen ions in the structure of the near-surface layer with the subsequent formation of gas-filled bubbles. During the studies carried out, it was found that at doses of irradiation with helium ions above 1х1017 ion/cm2 , there is a sharp deterioration in thermal conductivity and a decrease in ceramic resistance, which is associated with the onset of the formation of helium bubbles and partial embrittlement of the near-surface layer. However, an increase in the radiation dose above 5x1017 ion/cm2 does not lead to significant changes in thermal conductivity and insulation characteristics, which indicates the effect of radiation damage accumulation and a decrease in the ceramic degradation rate. In contrast to irradiation with helium ions, irradiation with hydrogen ions to doses higher than 1- 3х1017 ion/cm2 does not lead to significant changes in the thermal insulation characteristics, which indicates the ceramic resistance to hydrogen absorption processes.

Recombination Characteristics of Single-Crystalline Silicon Wafers with a Damaged Near-Surface Layer

2013 ◽  
Vol 58 (2) ◽  
pp. 142-150 ◽  
Author(s):  
A.V. Sachenko ◽  
◽  
V.P. Kostylev ◽  
V.G. Litovchenko ◽  
V.G. Popov ◽  
...  
Keyword(s):  
Surface Layer ◽  
Crystalline Silicon ◽  
Silicon Wafers ◽  
Single Crystalline Silicon ◽  
Near Surface ◽  
Single Crystalline

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

scholarly journals Crystal structure of K[Hg(SCN)3] – a redetermination

2014 ◽  
Vol 70 (9) ◽  
pp. i46-i46 ◽  
Author(s):  
Matthias Weil ◽  
Thomas Häusler
Keyword(s):  
Crystal Structure ◽  
Room Temperature ◽  
Three Dimensional ◽  
Lattice Parameters ◽  
Bond Lengths ◽  
Dimensional Network ◽  
Anisotropic Displacement Parameters ◽  
Precision And Accuracy ◽  
Standard Deviations ◽  
Atomic Coordinates

The crystal structure of the room-temperature modification of K[Hg(SCN)3], potassium trithiocyanatomercurate(II), was redetermined based on modern CCD data. In comparison with the previous report [Zhdanov & Sanadze (1952).Zh. Fiz. Khim.26, 469–478], reliability factors, standard deviations of lattice parameters and atomic coordinates, as well as anisotropic displacement parameters, were revealed for all atoms. The higher precision and accuracy of the model is, for example, reflected by the Hg—S bond lengths of 2.3954 (11), 2.4481 (8) and 2.7653 (6) Å in comparison with values of 2.24, 2.43 and 2.77 Å. All atoms in the crystal structure are located on mirror planes. The Hg2+cation is surrounded by four S atoms in a seesaw shape [S—Hg—S angles range from 94.65 (2) to 154.06 (3)°]. The HgS4polyhedra share a common S atom, building up chains extending parallel to [010]. All S atoms of the resulting1∞[HgS2/1S2/2] chains are also part of SCN−anions that link these chains with the K+cations into a three-dimensional network. The K—N bond lengths of the distorted KN7polyhedra lie between 2.926 (2) and 3.051 (3) Å.

scholarly journals Exploring the Structural Chemistry of Pyrophosphoramides: N,N′,N″,N‴-Tetraisopropylpyrophosphoramide

Chemistry ◽  
2021 ◽  
Vol 3 (1) ◽  
pp. 149-163
Author(s):  
Duncan Micallef ◽  
Liana Vella-Zarb ◽  
Ulrich Baisch
Keyword(s):  
Crystal Structure ◽  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Ir Spectroscopy ◽  
Room Temperature ◽  
Intermolecular Hydrogen Bonding ◽  
X Ray Diffraction ◽  
X Ray

N,N′,N″,N‴-Tetraisopropylpyrophosphoramide 1 is a pyrophosphoramide with documented butyrylcholinesterase inhibition, a property shared with the more widely studied octamethylphosphoramide (Schradan). Unlike Schradan, 1 is a solid at room temperature making it one of a few known pyrophosphoramide solids. The crystal structure of 1 was determined by single-crystal X-ray diffraction and compared with that of other previously described solid pyrophosphoramides. The pyrophosphoramide discussed in this study was synthesised by reacting iso-propyl amine with pyrophosphoryl tetrachloride under anhydrous conditions. A unique supramolecular motif was observed when compared with previously published pyrophosphoramide structures having two different intermolecular hydrogen bonding synthons. Furthermore, the potential of a wider variety of supramolecular structures in which similar pyrophosphoramides can crystallise was recognised. Proton (1H) and Phosphorus 31 (31P) Nuclear Magnetic Resonance (NMR) spectroscopy, infrared (IR) spectroscopy, mass spectrometry (MS) were carried out to complete the analysis of the compound.

Crystal structure of the anticancer drug carmustine determined by X-ray powder diffraction

2021 ◽  
pp. 1-3
Author(s):  
Carina Schlesinger ◽  
Edith Alig ◽  
Martin U. Schmidt
Keyword(s):  
Crystal Structure ◽  
Anticancer Drug ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Powder Diffraction Data ◽  
Orthorhombic Space Group ◽  
Commercial Sample ◽  
One Dimensional ◽  
X Ray ◽  
Hydrogen Bond Pattern

The structure of the anticancer drug carmustine (1,3-bis(2-chloroethyl)-1-nitrosourea, C5H9Cl2N3O2) was successfully determined from laboratory X-ray powder diffraction data recorded at 278 K and at 153 K. Carmustine crystallizes in the orthorhombic space group P212121 with Z = 4. The lattice parameters are a = 19.6935(2) Å, b = 9.8338(14) Å, c = 4.63542(6) Å, V = 897.71(2) ų at 153 K, and a = 19.8522(2) Å, b = 9.8843(15) Å, c = 4.69793(6) Å, V = 921.85(2) ų at 278 K. The Rietveld fits are very good, with low R-values and smooth difference curves of calculated and experimental powder data. The molecules form a one-dimensional hydrogen bond pattern. At room temperature, the investigated commercial sample of carmustine was amorphous.

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