Abstract
The lack of order in amorphous chalcogenides offers them novel properties but also adds increased challenges in the discovery and design of advanced functional materials. The amorphous ...compositions in the Si–Ge–Te system are of interest for many applications such as optical data storage, optical sensors and Ovonic threshold switches. But an extended exploration of this system is still missing. In this study, magnetron co-sputtering is used for the combinatorial synthesis of thin film libraries, outside the glass formation domain. Compositional, structural and optical properties are investigated and discussed in the framework of topological constraint theory. The materials in the library are classified as stressed-rigid amorphous networks. The bandgap is heavily influenced by the Te content while the near-IR refractive index dependence on Ge concentration shows a minimum, which could be exploited in applications. A transition from a disordered to a more ordered amorphous network at 60 at% Te, is observed. The thermal stability study shows that the formed crystalline phases are dictated by the concentration of Ge and Te. New amorphous compositions in the Si–Ge–Te system were found and their properties explored, thus enabling an informed and rapid material selection and design for applications.
The decay of the 21.47-MeV stretched resonance in 13C, arising from p3/2→d5/2 nucleon excitation coupled to maximum spin, was investigated in a (p,p′) experiment at 135 MeV proton bombarding energy, ...performed at the Cyclotron Centre Bronowice (CCB) at IFJ PAN in Krakow. First experimental information on the proton and neutron decay branches from this state was obtained by using coincidence measurement of protons inelastically scattered on a 13C target and γ rays from daughter nuclei, namely, 12B (proton decay) and 12C (neutron decay). The main branches lead to the Jπ=2+, first-excited state at 0.953 MeV in 12B, and to the Jπ=1+, T=1 level at 15.110 MeV in 12C. The results were compared with predictions from the Gamow Shell Model (GSM), which was used to describe the stretched resonance in terms of its energy, width, electromagnetic transition strengths and decay pattern. A very good agreement was obtained between the measured and calculated properties of the 21.47-MeV stretched resonance in 13C, demonstrating the high-quality and precision of the GSM wave function calculations, which include coupling to the resonant and non-resonant particle continuum.
The Horia Hulubei National Institute for Research & Development in Physics and Nuclear Engineering (IFIN-HH) operates, among other facilities, a 3 MV Tandetron™ accelerator, built by High Voltage ...Engineering Europa B.V. Since commissioning in 2012, the 3 MV Tandetron™ has emerged as an important tool to open new horizons in a variety of accelerator-based research fields. In other words, the 3 MV Tandetron™ accelerator has become one of the key facilities in the landscape of Romanian in both basic research and applications. In addition, our laboratory represents an adequate environment for training young scientists and undergraduates since they can develop marketable skills through accelerator-based research, such as data collection/analysis, software development or simulations. After a brief description of the facility, several prominent highlights defining our research capabilities are described. Finally, our ongoing and future upgrades plan is depicted.
Graphical abstract
We use an underground counting lab with an extremely low background to perform an activity measurement for the C12+13C system with energies down to Ec.m.=2.323 MeV, at which the 12C(13C,p)24Na cross ...section is found to be 0.22(7) nb. The C12+13C fusion cross section is derived with a statistical model calibrated using experimental data. Our new result of the C12+13C fusion cross section is the first decisive evidence in the carbon isotope systems which rules out the existence of the astrophysical S-factor maximum predicted by the phenomenological hindrance model, while confirming the rising trend of the S-factor towards lower energies predicted by other models, such as CC-M3Y+Rep, DC-TDHF, KNS, SPP and ESW. After normalizing the model predictions with our data, a more reliable upper limit is established for the C12+12C fusion cross sections at stellar energies.
This study addresses the deposition with improved adhesion of TiO
2
:N/SiO
2
mixture, with different concentrations of the nano-powders (NPs) (1:0,5; 1:1 and 1:1,5) on 100% cotton fabrics. The ...characteristics of the deposited thin films were investigated by scanning electron microscopy (SEM), Rutherford backscattering spectrometry (RBS), Raman scattering, FTIR, and UV-VIS absorption spectroscopy. To improve the treatment durability to the external factors, the different crosslinking methods were used. Photocatalytic activity of functionalized textile fabrics was evaluated by determining the photodegradation efficiency of the methylene blue (MB) dye and forest juice, measuring the color difference of the irradiated samples compared with non-irradiated samples. Washing durability of the samples was achieved qualitatively by determining the photocatalytic activity remaining on the textile fabrics after 1 and 5 washing cycles. The samples treated with the mixture of TiO
2
:N/SiO
2
have demonstrated improved self-cleaning properties, the highest photocatalytic activity being obtained for the highest value of TiO
2
:N/SiO
2
NPs molar concentrations equal to 1:1.
An alkaline earth boro-aluminosilicate glass (Eagle XG), a soda-lime glass, and a light-weight polyethylene-terephthalate (PET) foil, used as typical substrates for photovoltaics, were treated by an ...energetic proton beam (3 MeV, dose 106–107 Gy) corresponding to approx. 30 years of operation at low Earth orbit. Properties of the irradiated substrates were characterized by atomic force microscopy, optical absorption, optical diffuse reflectance, Raman spectroscopy, X-ray photoelectron spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and terahertz (THz) spectroscopy. Minimal changes of optical and morphological properties are detected on the bare Eagle XG glass, whereas the bare PET foil exhibits pronounced increase in optical absorption, generation of photoluminescence, as well as mechanical bending. On the other hand, the identical substrates coated with Indium-tin-oxide (ITO), which is a typical material for transparent electrodes in photovoltaics, exhibit significantly higher resistance to the modifications by protons while ITO structural and electronic properties remain unchanged. The experimental results are discussed considering a potential application of these materials for missions in space.
•Optical absorption in PET foil significantly increases after proton irradiation.•ITO coating reduces proton-induced degradation.•Boro-aluminosilicate glass resists well to proton beam.•No microscopic topography change on ITO due to proton irradiation.•Minimal ITO work function change after proton irradiation.
•D retention in W co-deposited layers is strongly dependent on the ion energy.•D retention is favored by Ne rather than Ar.•Ne inclusions generate tensile stressed layers.•Ar inclusions generate ...compressive stressed layers.•nuclear fuel and seeding impurities concentration is almost constant throughout the depth of the co-deposited layers.
Deuterium (D) retention in tungsten (W) co-deposited layers, in the presence of neon (Ne) and argon (Ar), was investigated using the bipolar High Power Impulse Magnetron Sputtering (BP-HiPIMS) technique. The deposited layers have a polycrystalline structure, with a preferential growth of W(110) phase. The concentration of D and noble gases (Ne and Ar) is almost constant throughout the depth of the layers. In a D2-Ar discharge, the deposited layers exhibit compressive stress, indicating that Ar is mostly incorporated into the interstitial sites of the W crystal lattice. D retention increases when Ne is added in the discharge, especially when the deposited layer is bombarded with highly energetic ions. Low energy Ne ions (below the W damaging threshold) induce compressive stress, indicating that Ne atoms occupy interstitial sites in the W crystal lattice. High energy Ne ions induce tensile stress, a sign that Ne is trapped in the grain boundaries as inert-gas-vacancy defects, leading to a grain-boundary relaxation. In the presence of Ne, the ion acceleration towards the layer from 0 V to 300 V results in an increase of the D content of about three times, from 3.2 at.% to 8.6 at.%.
Beryllium-tungsten 2μm thick layers were co-deposited on molybdenum, graphite and silicon substrates in a reactive argon-deuterium/argon-deuterium-nitrogen gas mixture by means of combining ...multi-pulse High Power Impulse Magnetron Sputtering and Direct Current Magnetron Sputtering techniques. The elemental composition and thickness of the layers were well controlled during the deposition process. Structural and chemical investigations were undertaken by means of X-ray diffraction and Rutherford backscattering methods. The results showed a change in the samples structure with the adding of nitrogen into the sputtering gas mixture, evidenced by the appearance of W2N peaks in the diffraction patterns. The RBS showed in-depth uniformity of beryllium and tungsten concentrations for the deposited coatings. In order to investigate the deuterium retention mechanisms and to make an assessment of the deuterium inventory, thermal desorption spectrometry was performed. The deuterium desorption spectra for the batch of samples obtained with nitrogen showed an obvious behaviour of shifting to higher temperatures. This behaviour may be related to the nitrogen desorption.
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•Deuterium retention and release study performed on beryllium tungsten codeposited mixed layers.•Formation of a nitride for layers co-deposited with nitrogen.•Nitrogen acts as a trapping state barrier for deuterium shifting its thermal release.•Deuterium retention is strongly influenced by the nature of the substrate.
•Successful growth of W films with Ne-Ar contents up to 3 at.% using bipolar HiPIMS.•The amount of Ne-Ar in W films is determined by ion energy and flux to substrate.•Ion energy is related to ...positive pulse voltage, ion flux to negative pulse width.•Highest film crystallinity for a positive pulse of 200 V and a negative pulse of 5 µs.
This work is focused on controlling and optimizing the inclusion of neon (Ne) and argon (Ar) impurities in tungsten (W) reference coatings. A tungsten target has been sputtered in monopolar and bipolar High Power Impulse Magnetron Sputtering (HiPIMS) operation modes, in Ar-Ne gas mixture. It has been found that the process of noble gas retention in W thin layers is strongly dependent on both ion energy and average flux to the substrate. The ion energy can be accurately controlled by the amplitude of the positive voltage pulse while the average ion flux can be controlled by the duration of the negative pulse. Measurements of the plasma potential in front of the substrate and the ion saturation current at the substrate position allow explaining the mechanism of ion acceleration and the control of ion energy and flux. The effect of the pulsing configuration on the microstructure of the co-deposited films has been investigated by X-ray Diffractometry, Scanning Electron Microscopy and Atomic Force Microscopy, while the amount of noble gas enclosed in the coatings has been measured by Non-Rutherford Backscattering Spectrometry. Ne and Ar amount in the W co-deposited layers increases up to 3.0 at.% each as the amplitude of the positive pulse increases to + 300 V or the negative pulse duration decreases to 3 µs. The highest film crystallinity, with W(110) preferential growth, has been obtained for a positive pulse voltage of + 200 V and a negative pulse duration of 5 µs. The thickness of the deposited layers ranges between 350 nm in bipolar HiPIMS with a positive pulse voltage of + 300 V and 550 nm in monopolar HiPIMS.
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