The behavior of implanted deuterium in advanced lithium orthosilicate (Li4SiO4) pellets with addition of lithium metatitanate (Li2TiO3), and in reference Li4SiO4 pellets, has been investigated. Thermal desorption (TD) spectroscopy was used to study the deuterium interaction with radiation defects in materials. Computational evaluation of deuterium desorption within the framework of the diffusion-trapping model allowed to associate characteristics of experimental TD spectra with specific trapping sites in the material. It was found that deuterium desorption is limited mainly by intragranular diffusion of deuterium and its trapping by radiation defects associated with Li-vacancy traps. Deuterium gas release from both ceramics demonstrated similar trend indicating weak dependence of deuterium trapping behavior on phase composition. The change of the morphology and elemental composition of the pellets surface has been analyzed. SEM examination indicated that ion irradiation and subsequent thermal desorption annealing of two-phase ceramics leads to an increase in surface destruction processes.
The effect of radiation damage on the retention of deuterium in tungsten (W) was examined. A vacuum-arc plasma source with magnetic stabilization of the cathode spot was used for tungsten coatings preparation. W samples were treated with D ions at temperatures 300‑600 K with a fluence of (1 – 10) ·1020 D2+/m2 and ion energies of 12 keV/D2+. The influence of radiation damage on microstructure and accumulation of deuterium implanted in W samples at room temperature and after annealing have been studied. Thermal desorption (TD) spectroscopy was used to determine the D retained throughout the bulk of the sample. The structure of TD spectra represents the multi-stage process of deuterium release suggesting the trapping of gas atoms by a number of defect types. Computational evaluation of deuterium desorption within the framework of the diffusion-trapping model allows to associate characteristics of experimental TD spectra with specific trapping sites in the material. Experimental TD spectrum was fitted by assigning four binding energies of 0.55 eV, 0.74 eV, 1.09 eV and 1.60 eV for the peaks with maxima at 475, 590, 810 and 1140 K, respectively. The low temperature peak in the TD spectra is associated with desorption of deuterium bounded to the low energy natural traps, whereas the other peaks are related to the desorption of deuterium bounded to the high energy ion induced traps: monovacancies and vacancy clusters.
The kinetics of helium porosity development during annealing of 18Cr10NiTi stainless steel irradiated with 20 keV helium ions at room temperature for simultaneous creation of displacement damage at a level of 0.5–5 dpa and a helium concentration of 1–12 at.%, have been investigated by electron microscopy and thermal desorption spectrometry. The temperature ranges of helium release from steel and their dependence on the irradiation dose are determined. The evolution of 18Cr10NiTi steel microstructure was investigated during post-implantation annealing in the temperature range from Troom to 1420 K. At a dose of 1·1020 m-2, helium bubbles were detected only after annealing to a temperature of 890 K, while at a dose of 1·1021 m-2, bubbles were observed immediately after radiation at Troom. During annealing, the average diameters of the bubbles vary from ~1 nm at Troom to 10–20 nm at Tann 1420 K. The mechanisms of bubbles growth either by migration and coalescence, or by Ostwald ripening – dissolution and re-trapping are considered. Since each of these mechanisms corresponds to a certain trend of bubbles size and density dependence on the annealing temperature, the temperature dependences of average diameters and densities of helium bubbles for a dose of 1·1021 m-2 have been constructed and analyzed. Experimental data are characterized by three temperature ranges: 1 – from 300 to 760 K, 2 – from 760 to 1030 K, and 3 – from 1030 to 1350 K with clearly differing trends. In the low-temperature region the diameter and density of the bubbles virtually does not change. Their size increases and the density decreases at annealing in the temperature range 760-1030 K. This tendency intensifies in the temperature range of 1030-1420 K. An estimation of activation energy of the processes controlling the mechanism of bubble growth in the temperature range of 1000-1420 K has been done. An obtained value of ~3.7 eV correlates well with the theoretically calculated value of the activation energy of the dissociation process (EHediss) of the Ostwald ripening mechanism.
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