Search results for "Rumen"
showing 10 items of 5946 documents
Ab initio modelling of the Y, O, and Ti solute interaction in fcc-Fe matrix
2018
Abstract Strengthening of the ODS steels by Y2O3 precipitates permits to increase their operation temperature and radiation resistance, which is important in construction materials for future fusion and advanced fission reactors. Both size and spatial distribution of oxide particles significantly affect mechanical properties and radiation resistance of ODS steels. Addition of the Ti species (present also as a natural impurity atoms in iron lattice) in the particles of Y2O3 powder before their mechanical alloying leads to the formation of YTiO3, Y2TiO5, and Y2Ti2O7 nanoparticles in ODS steels. Modelling of these nanoparticle formation needs detailed knowledge of the energetic interactions be…
Analysis of thin high-k and silicide films by means of heavy ion time-of-flight forward-scattering spectrometry
2006
The use of forward scattered heavy incident ions in combination with a time-of-flight-energy telescope provides a powerful tool for the analysis of very thin (5–30 nm) films. This is because of greater stopping powers and better detector energy resolution for heavier ions than in conventional He-RBS. Because of the forward scattering angle, the sensitivity is greatly enhanced, thus reducing the ion beam induced desorption during the analysis of very thin films. The drawback of forward scattering angle is the limited mass separation for target elements. We demonstrate the performance of the technique with the analysis of 25 nm thick NiSi films and atomic layer deposited 6 nm thick HfxSiyOz f…
Ion track template technology for fabrication of CdTe and CdO nanocrystals
2020
Abstract CdTe and CdO nanocrystals were synthesized by chemical deposition into a-SiO2/n-Si ion track template formed by 200 MeV Xe ion irradiation with the fluence of 108 ions/cm2. Depending on the temperature of the solution CdTe + CdO and single-phase CdO with a hexagonal crystal structure were obtained, respectively. The study of the current – voltage characteristics of the obtained structure with the single-phase CdO allows us to estimate the number of grain boundaries and the height of the potential barrier, as well as the n-type conductivity.
Accumulation of radiation defects and modification of micromechanical properties under MgO crystal irradiation with swift 132Xe ions
2020
This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 and 2019-2020 under grant agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. A.A. also acknowledges support via the project GF AP05134257 of Ministry of Education and Science of the Republic of Kazakhstan .
Shallow and deep trap levels in X-ray irradiated β-Ga2O3: Mg
2019
Abstract The results of the investigation of thermostimulated luminescence (TSL) and photoconductivity (PC) of the X-ray irradiated undoped and Mg2+ doped β-Ga2O3 single crystals are presented. Three low-temperature peaks at 116 K, 147 K and 165 K are observed on the TSL glow curves of undoped crystals. The high-temperature TSL peaks at 354 K and 385 K are dominant in Mg2+ doped crystals. The correlation between doping with Mg2+ ions and the local energy levels of the intrinsic structural defects of β-Ga2O3, which are responsible for the TSL peaks and PC, is established. The nature of TSL peaks and the appropriate photoconductivity excitation bands are discussed.
EPR and optical spectroscopy of neutron-irradiated Gd3Ga5O12 single crystals
2020
Abstract In this paper, we have performed comparative analysis of EPR, optical absorption (OA) and luminescence spectra for a series of Gd3Ga5O12 (GGG) single crystals irradiated with fast neutrons with fluencies varied from 1016 to 1020n/cm2. In a crystal irradiated with the maximum neutron fluence, the EPR spectra demonstrated the formation of several paramagnetic defects. In particular, EPR spectrum shows a strong resonance at (effective) g ≈ 1.4 with practically isotropic behavior in the crystal rotation around the [1 1 1] direction (magnetic field being perpendicular to [1 1 1]) and several weaker lines in the g ≈ 1.1–2.6 region, which show more pronounced angular dependences. While th…
Comparison of the F-type center thermal annealing in heavy-ion and neutron irradiated Al2O3 single crystals
2018
Abstract The optical absorption and thermally stimulated luminescence of Al2O3 (sapphire) single crystals irradiated with swift heavy ions (SHI) 238U with energy 2.4 GeV is studied with the focus on the thermal annealing of the F-type centers in a wide temperature range of 400–1500 K. Its theoretical analysis allows us to obtain activation energies and pre-exponentials of the interstitial oxygen ion migration, which recombine with both types of immobile electron centers (F and F+ centers). A comparison of these kinetics parameters with literature data for a neutron-irradiated sapphire shows their similarity and thus supports the use of SHI-irradiation for modeling the neutron irradiation.
Thermal annealing of radiation damage produced by swift 132Xe ions in MgO single crystals
2020
Abstract The annealing kinetics of the electron-type F+ and F color centers in highly pure MgO single crystals irradiated by 0.23-GeV 132Xe ions with fluences covering three orders of magnitude (Φ = 5 × 1011 –3.3 × 1014 ions/cm2) are studied experimentally via dependence of the optical absorption on preheating temperature. The annealing data are analyzed in terms of the diffusion-controlled bimolecular reactions between F-type centers and complementary interstitial oxygen ions. The behavior of the main kinetic parameters – the migration energies and pre-exponential factors – for different irradiation fluences is discussed and compared with that for other wide-gap binary materials from previ…
Stopping cross-section measurements of 4He in TiN1.1O0.27
2000
Abstract The stopping cross-section for 4He projectiles in TiNx compounds has been measured using the backscattering method. A multi-compound marker layer deposited between the test film and the substrate was used to obtain the stopping cross-section at several energies with one energy of the incident beam. Two RBS spectra at definite tilt angles of the sample are taken for each beam energy. The assistance of computer codes to synthesize RBS spectra is very useful to obtain the pertinent information from the displacements of the peaks of the marker layers. Stopping cross-section values are obtained with an estimated uncertainty of about 6%.
Lattice sites of diffused gold and platinum in epitaxial ZnSe layers
2000
Abstract The lattice location of diffused gold and platinum in zinc selenide (ZnSe) epitaxial layers was studied using the Rutherford backscattering (RBS) channeling technique. Thin Au and Pt films were evaporated onto ZnSe samples. The Au/ZnSe samples were annealed at 525°C and the residual Au film was removed by etching. Channeling angular scan measurements showed that about 30% of Au atoms were close to substitutional site (displaced about 0.2 A). In the case of the Pt/ZnSe samples the annealing temperatures ranged from 600°C to 800°C. The Pt minimum yields along 〈1 0 0〉 direction were close to the random value, varying from 80% to 90%. The measured Pt angular scans along 〈1 0 0〉 and 〈1 …